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Journal articles on the topic 'Fungicide'
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1
Tarnowski, T. L. B., A. T. Savelle, and H. Scherm. "Activity of Fungicides Against Monilinia vaccinii-corymbosi in Blueberry Flowers Treated at Different Phenological Stages." Plant Disease 92, no. 6 (June 2008): 961–65. http://dx.doi.org/10.1094/pdis-92-6-0961.
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The activity of fenbuconazole and azoxystrobin applied to blueberry flowers at different phenological stages against subsequent gynoecial infection by the mummy berry fungus Monilinia vaccinii-corymbosi was evaluated. In the greenhouse, potted blueberry plants having flower clusters at five distinct stages (from bud scale separation to anthesis) were treated with the two fungicides. One day after anthesis (between 1 and 15 days after fungicide treatment), individual flowers were detached and inoculated with conidia of M. vaccinii-corymbosi in the laboratory. Four days after inoculation, hyphal ingress into the style was determined microscopically as a measure of fungicide efficacy. Results revealed a significant flower stage effect (P < 0.0001), whereby only fungicide application at anthesis but not at the four preanthesis stages reduced subsequent fungal ingress into the style. There was no significant difference between the two fungicides (P > 0.50) nor was there a significant fungicide–flower stage interaction (P > 0.30). In the field during 2 years, mature blueberry plants were treated with the two fungicides and exposed to natural pathogen inoculum. At the time of application, flower clusters at anthesis and at three preanthesis stages were selected and tagged. Mummy berry incidence in fruit developing from the tagged clusters was assessed to determine treatment effects. Whereas fenbuconazole lowered disease incidence for all preanthesis stages, azoxystrobin was effective only at the latest preanthesis stage. The discrepancy between these results and those of the greenhouse study (where there was no preanthesis activity of either fungicide) indirectly suggests post-infection fungicidal activity in the ovary, the base of which was exposed to the fungicide spray at the time of treatment for all flower phenology stages. Thus, although there appears to be insufficient translocation of the two fungicides in flowers treated at preanthesis stages to prevent stylar ingress by the pathogen, fungicidal activity in the ovary may be sufficient to halt subsequent fungal colonization, especially for fenbuconazole. To prescribe the most effective management program for flower-infecting fungi, translocation and post-infection activity of fungicides in floral tissues must be better understood.
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O'Brien, RG, LL Vawdrey, and RJ Glass. "Fungicide resistance in cucurbit powdery mildew (Sphaerotheca fuliginea) and its effect on field control." Australian Journal of Experimental Agriculture 28, no. 3 (1988): 417. http://dx.doi.org/10.1071/ea9880417.
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Decreased fungicidal control of powdery mildew (Sphaerotheca fuliginea (Schlecht: Fr.) Poll.) in commercial cucurbit crops led to an investigation to determine whether fungicide resistant strains were present. In field trials, fungicides such as bupirimate (100 mg a.i. L-I), dimethirimol (250 mg a.i. L-1), fenarimol (36 mg a.i. L-1), penconazole (40 mg a.i. L-l) and triadimefon (125 mg a.i. L-1) were less effective (P=0.01) in controlling the disease than oxythioquinox (100 mg a.i. L-1). This disagreed with earlier trial results and suggested that fungicide resistant strains may have developed. The sensitiyities of 6 isolates of S. fuliginea to 12 fungicides were determined using a leaf disc technique. Two isolates collected in fields where fungicides had been used intensively showed reduced sensitivity to fungicides from several chemical groups including the ergosterol biosynthesis inhibitors, hydroxypyrimidines, organophosphates and benzimidazoles. Several spraying strategies were compared. The S. fuliginea populations receiving spray schedules which included the protectant fungicide oxythioquinox alone, or in alternation with a systemic (triadimefon) developed a lower proportion (66-73%) of resistant strains than those treated with systemic fungicide alone (89%). These findings suggest that S. fuliginea can develop strains with low sensitivity to several fungicides against powdery mildew. To prolong their efficacy, systemic fungicides should not be used continuously but should be reserved for use during the latter part of crop growth when disease risk is highest. Alternating or tank mixing with an effective protectant fungicide is also recommended.
3
Tompros, Adrianna, Mark Q. Wilber, Andy Fenton, Edward Davis Carter, and Matthew J. Gray. "Efficacy of Plant-Derived Fungicides at Inhibiting Batrachochytrium salamandrivorans Growth." Journal of Fungi 8, no. 10 (September 28, 2022): 1025. http://dx.doi.org/10.3390/jof8101025.
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The emerging fungal amphibian pathogen, Batrachochytrium salamandrivorans (Bsal), is currently spreading across Europe and given its estimated invasion potential, has the capacity to decimate salamander populations worldwide. Fungicides are a promising in situ management strategy for Bsal due to their ability to treat the environment and infected individuals. However, antifungal drugs or pesticides could adversely affect the environment and non-target hosts, thus identifying safe, effective candidate fungicides for in situ treatment is needed. Here, we estimated the inhibitory fungicidal efficacy of five plant-derived fungicides (thymol, curcumin, allicin, 6-gingerol, and Pond Pimafix®) and one chemical fungicide (Virkon® Aquatic) against Bsal zoospores in vitro. We used a broth microdilution method in 48-well plates to test the efficacy of six concentrations per fungicide on Bsal zoospore viability. Following plate incubation, we performed cell viability assays and agar plate growth trials to estimate the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of each fungicide. All six fungicides exhibited inhibitory and fungicidal effects against Bsal growth, with estimated MIC concentrations ranging from 60 to 0.156 μg/mL for the different compounds. Allicin showed the greatest efficacy (i.e., lowest MIC and MFC) against Bsal zoospores followed by curcumin, Pond Pimafix®, thymol, 6-gingerol, and Virkon® Aquatic, respectively. Our results provide evidence that plant-derived fungicides are effective at inhibiting and killing Bsal zoospores in vitro and may be useful for in situ treatment. Additional studies are needed to estimate the efficacy of these fungicides at inactivating Bsal in the environment and treating Bsal-infected amphibians.
4
Ngibad, Khoirul, Afidatul Muadifah, Lailatul Jannah Triarini, Laily Rizki Amalia, and Novita Karel Damayanti. "A review of application of natural products as fungicides for chili." Environmental and Toxicology Management 1, no. 2 (May 22, 2021): 9–22. http://dx.doi.org/10.33086/etm.v1i2.2022.
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Anthracnose disease in chillies is a serious problem for farmers. So far, synthetic fungicides have been used as solution for the treatment of this disease. However, the side effects of synthetic fungicides to public health and environment raised awareness on alternative fungicides derived from natural resources. This paper aims to review plants that are potential as an alternative to fungicides for chili plantation, fabrication of test solutions, in vitro and in vivo fungicide test. Many plants were investigated as alternatives to plant-based fungicide. The utilization of leaves as samples including rhizomes, roots, tubers, weevils, seeds, fruit, flowers and other parts of the plant. The extract fabrication method used as a fungicide test include: maceration method, gradual fractionation method, and decoction method. The maceration method is the method most widely used to extract fungicidal active compounds from plants. Some studies that carried out in vitro tests were unable to compare with synthetic fungicides so it was not possible to determine their effectiveness for plant-based fungicide for chillies when compared to synthetic fungicides. In vitro Extract of 80% alcohol and 10%/60% n-hexane of pacar cina (Aglaia odorata L.) leaves can be compared with the performance of propineb 0.2%. In addition, the 60% and 70% kirinyuh (Chromolaena odorata L.) leaf extracts were also able to match Acrobat 0.2% performance in vitro. Based on the in vivo test, suren (Toona sureni Merr) leaf extract and nut bulbs can be used as an alternative to vegetable / natural fungicides to help overcome the problem of anthracnose in chilies.
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Bandara, Ananda Y., Dilooshi K. Weerasooriya, Shawn P. Conley, Tom W. Allen, and Paul D. Esker. "Modeling the relationship between estimated fungicide use and disease-associated yield losses of soybean in the United States II: Seed-applied fungicides vs seedling diseases." PLOS ONE 15, no. 12 (December 28, 2020): e0244424. http://dx.doi.org/10.1371/journal.pone.0244424.
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Use of seed-applied fungicides has become commonplace in the United States soybean production systems. Although fungicides have the potential to protect seed/seedlings from critical early stage diseases such as damping-off and root/stem rots, results from previous studies are not consistent in terms of seed-applied fungicide’s ability to mitigate yield losses. In the current study, the relationship between estimated soybean production losses due to seedling diseases and estimated seed-applied fungicide use was investigated using annual data from 28 soybean growing states in the U.S. over the period of 2006 to 2014. National, regional (northern and southern U.S.), state, and temporal scale trends were explored using mixed effects version of the regression analysis. Mixed modeling allowed computing generalized R2 values for conditional (R2GLMM(c); contains fixed and random effects) and marginal (R2GLMM(m); contains only fixed effects) models. Similar analyses were conducted to investigate how soybean production was related to fungicide use. National and regional scale modeling revealed that R2GLMM(c) values were significantly larger compared to R2GLMM(m) values, meaning fungicide use had limited utility in explaining the national/regional scale variation of yield loss and production. The state scale analysis revealed the usefulness of seed-applied fungicides to mitigate seedling diseases-associated soybean yield losses in Illinois, Indiana, North Carolina, and Ohio. Further, fungicide use positively influenced the soybean production and yield in Illinois and South Dakota. Taken together, use of seed-applied fungicide did not appear to be beneficial to many of the states. Our findings corroborate the observations made by a number of scientists through field scale seed-applied fungicide trials across the U.S and reiterate the importance of need base-use of seed-applied fungicides rather than being a routine practice in soybean production systems.
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Gur, Lior, Keren Levy, Amotz Farber, Omer Frenkel, and Moshe Reuveni. "Delayed Development of Resistance to QoI Fungicide in Venturia inaequalis in Israeli Apple Orchards and Improved Apple Scab Management Using Fungicide Mixtures." Agronomy 11, no. 2 (February 23, 2021): 396. http://dx.doi.org/10.3390/agronomy11020396.
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Quinone outside inhibitors (QoI) fungicides group were introduced for commercial use against apple scab (Venturia inaequalis) in Israel in 1997. Unlike other regions in the world, in which resistance of V. inaequalis to QoI fungicides was observed within 3–5 years of use, in Israel it only occurred after 14 years of use. Field trials conducted between 2007 and 2017 showed a significant reduction in susceptibility to QoIs in northern Israel only since 2011. The delay in the development of resistance is related to limited fungicidal sprays resulting from unfavorable conditions for the pathogen. Of the 28 isolates collected from infected leaves or fruits of commercial orchards in northern Israel, 27 were resistant to the QoI fungicide Kresoxim-methyl. Amplification of the CYTB gene and sequencing of the G143A mutation region confirmed the resistance of all 27 isolates to QoIs. Resistance is demonstrated in the orchard, in vitro and molecular-based study, which forced the growers to avoid using QoIs against apple scab. We show that foliar applications of tank mixtures of systemic fungicides plus captan or prepacked fungicidal mixtures improved efficacy and can be used as a strategic approach in fungicide resistance management, including in orchards in which resistance to QoIs has been detected.
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Gent, David H., Mary Block, and Briana J. Claassen. "High Levels of Insensitivity to Phosphonate Fungicides in Pseudoperonospora humuli." Plant Disease 104, no. 5 (May 2020): 1400–1406. http://dx.doi.org/10.1094/pdis-10-19-2067-re.
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Phosphonate (phosphite; HPO3−2) is fungicidal against oomycetes and certain other organisms. The Fungicide Resistance Action Committee has deemed phosphonate to be at low risk of resistance development, and reduced sensitivity to phosphonate has been reported only occasionally in plant pathogens. Reduced sensitivity to the fungicide fosetyl-Al was documented in the hop downy mildew pathogen, Pseudoperonospora humuli, in the early 2000s, but disease caused by insensitive isolates could still be managed commercially if the fungicide rate was doubled from 2.24 to 4.48 kg/ha. In this research, we document the occurrence of isolates of P. humuli in Oregon that possess even higher levels of insensitivity to fosetyl-Al and other phosphonate fungicides. The median estimated effective concentration required to reduce infection by 50% (EC50) for isolates collected from two farms reporting disease control failures was 2.7% (vol/vol) phosphonate (range = 1.6 to 164.2), which was 1.6 times (range = 0.9 to 96.0) the maximum labeled rate of the phosphonate fungicide utilized. In contrast, the median EC50 for isolates obtained from experimental plots that have received only a single application of a phosphonate fungicide was 0.6% (vol/vol) phosphonate (range = 0.11 to 2.3) or 0.3 times the maximum allowable rate. Sensitivity of isolates to a phosphorous acid fungicide, fosetyl-Al, and a plant nutrient product containing an unspecified level of phosphorous acid were linearly related. Insensitivity to the maximum allowable rate of a phosphorous acid fungicide was widespread within and among hop farms in Oregon. Among 54 isolates assayed for phosphonate insensitivity, 96% had EC50 values that exceeded the maximum allow rate of the fungicide used in the assays. Field studies conducted in 2 years further demonstrated that a phosphorous fungicide, a nutrient product containing phosphorous acid, and fosetyl-Al failed to provide commercially acceptable suppression of downy mildew when applied at the maximum allowable rates and even double these rates, whereas fungicides with different modes of action provided 91% or greater disease control. The whole of this research indicates that P. humuli has been selected to tolerate fosetyl-Al and other phosphonate fungicides at rates four times greater than those used earlier to obtain satisfactory suppression of downy mildew. This finding has implications for management of the disease not only in Oregon but also, in other production regions should insensitive isolates be introduced on infected planting material.
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Ali, Md Emran, Owen Hudson, Will H. Hemphill, Timothy B. Brenneman, and Jonathan E. Oliver. "First Report of Resistance to Pyraclostrobin, Boscalid, and Thiophanate-methyl in Colletotrichum gloeosporioides from Blueberry in Georgia." Plant Health Progress 20, no. 4 (January 1, 2019): 261–62. http://dx.doi.org/10.1094/php-08-19-0058-br.
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Colletotrichum gloeosporioides causes anthracnose fruit rot and leaf spot on blueberries. For controlling anthracnose, blueberry growers mostly rely on pre- and postharvest fungicide applications in addition to orchard sanitation. Single-site fungicides including quinone outside inhibitors (QoIs), such as pyraclostrobin and azoxystrobin as well as fungicides containing the succinate dehydrogenase inhibitor (SDHI) boscalid are used frequently to control anthracnose rots and other diseases on blueberry; however, development of fungicide resistance is a real risk because a limited number of fungicides are now available for blueberry disease management. In 2019, three isolates of C. gloeosporioides were cultured from blueberry fruit collected from southern highbush blueberry cultivar ‘Farthing’ in two commercial blueberry fields in Pierce County, Georgia, where ripe rot had been a problem. Fungicide sensitivity tests were conducted using a mycelial growth inhibition assay as described previously. A total of nine fungicides were evaluated to determine the sensitivity of these C. gloeosporioides isolates. All three isolates were resistant to thiophanate-methyl, the QoI fungicide pyraclostrobin, and the SDHI fungicide boscalid. These findings suggest that continuous monitoring of fungicide resistance is necessary to avoid the unwarranted application of single-site fungicides.
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Raper, Tyson B., Dan D. Fromme, Darrin M. Dodds, Gaylon Morgan, Randy Boman, Shawn A. Butler, and W. Hunter Frame. "Evaluation of Early Season Foliar Fungicide Applications to Support Non-Fungicidal ‘Plant Health’ Benefits." Journal of Cotton Science 23, no. 1 (2019): 7–13. http://dx.doi.org/10.56454/adtj9206.
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The recent labeling of a new fungicide and rumors of non-fungicidal ‘plant health’ benefits achieved through early-season foliar applications of certain fungicides have led to inquiries concerning the practice. The objective of this research was to determine the impact of an early-season fungicide application on early-season growth or end-of-season lint yields, turnout, and/or fiber quality when disease symptoms are not present. During the 2014-2016 growing seasons, a total of ten trials were established in Alexandria, LA; Starkville, MS; Fort Cobb, OK; Jackson, TN; and Snook, TX. Fungicide treatments included an untreated control, a foliar application of 0.11 kg ai ha-1 zoxystrobin, and a foliar application of 0.07 kg ai ha-1 fluxapyroxad + 0.15 kg ai ha-1 pyraclostrobin. All treatments targeted the two through four true leaf growth stage. A significant interaction between fungicide treatment and site-year was observed from node counts collected at 14 and 28 DAA. Site-year analysis indicated a significant reduction in node counts observed with the azoxystrobin treatment in one site-year in the 14 DAA data and one site-year in the 28 DAA data. Fungicide treatment did not impact plant height or vigor ratings collected at 14 or 28 DAA, chlorophyll meter readings, lint yield, turnout, or fiber quality parameters in any site-year. Failure of fungicide treatments to positively impact in-season growth measurements, yield, and yield parameters suggests the evaluated fungicides should not be applied early-season for the purpose of improving ‘plant health’ and should instead be reserved to target above-threshold levels of disease incidence/severity.
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N. Srinivasan and M. Gunasekaran. "FIELD CONTROL OF LEAF ROT DISEASE OF COCONUT WITH FUNGICIDES." CORD 12, no. 02 (December 1, 1996): 34. http://dx.doi.org/10.37833/cord.v12i02.303.
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Leaf rot is a disease of fungal complex super imposed on root (wilt) affected coconut palms in India. A field fungicidal control trial on the disease involving contact (indofil M‑45, Fytolan) and systemic (Calixin) fungicides was conducted Fungicidal treatments, spraying of Indofil M‑45 and pouring of Calixin into axil of spindle, were found beneficial as the disease intensity reduced in newly emerged leaves. However, the extent of disease amelioration by fungicides was marginal to moderate level only. Importance of broad spectrum fungicide(s) and measures of disease protection are outlined.
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Wyenandt, Christian A., and Nancy L. Maxwell. "Determining “Practical” Fungicide Resistance Development and Drift in the Control of Cucurbit Powdery Mildew in Pumpkin." Plant Health Progress 11, no. 1 (January 2010): 4. http://dx.doi.org/10.1094/php-2010-1122-02-rs.
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In 2006 and 2007, nine fungicides were evaluated to determine if “practical” fungicide resistance could be identified and if fungicide resistance drift occurred in cucurbit powdery mildew of pumpkin. The fungicides and/or tank mixes whose active ingredient(s) were evaluated included: sulfur (FRAC code M1), chlorothalonil (M5), myclobutanil (3), pyraclostrobin (11), azoxystrobin (11), quinoxyfen (13), chlorothalonil + myclobutanil (M5 + 3), famoxadone + cymoxanil (11 + 27), pyraclostrobin + boscalid (11 + 7), and water only (control). Based on visual ratings of upper and lower leaf surfaces, a FRAC code 11 resistance cucurbit powdery mildew population was present in both years. Practical resistance and cross resistance were identified where a FRAC code 11 fungicide had not been applied season-long as well as where a FRAC code 11 fungicide was applied weekly or in rotation with another fungicide chemistry. Resistance to a FRAC code 3 fungicide was not identified where a FRAC code 3 fungicide had been applied season-long, or in rotation, or where no FRAC code 3 fungicide was applied. This study demonstrates that cucurbit powdery mildew populations resistant and/or cross resistant to FRAC code 11 fungicides can develop and have the potential to disseminate into and be detected in areas where no FRAC code 11 fungicides have been applied. Accepted for publication 11 October 2010. Published 22 November 2010.
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van den Bosch, Frank, Neil Paveley, Femke van den Berg, Peter Hobbelen, and Richard Oliver. "Mixtures as a Fungicide Resistance Management Tactic." Phytopathology® 104, no. 12 (December 2014): 1264–73. http://dx.doi.org/10.1094/phyto-04-14-0121-rvw.
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We have reviewed the experimental and modeling evidence on the use of mixtures of fungicides of differing modes of action as a resistance management tactic. The evidence supports the following conclusions. 1. Adding a mixing partner to a fungicide that is at-risk of resistance (without lowering the dose of the at-risk fungicide) reduces the rate of selection for fungicide resistance. This holds for the use of mixing partner fungicides that have either multi-site or single-site modes of action. The resulting predicted increase in the effective life of the at-risk fungicide can be large enough to be of practical relevance. The more effective the mixing partner (due to inherent activity and/or dose), the larger the reduction in selection and the larger the increase in effective life of the at-risk fungicide. 2. Adding a mixing partner while lowering the dose of the at-risk fungicide reduces the selection for fungicide resistance, without compromising effective disease control. The very few studies existing suggest that the reduction in selection is more sensitive to lowering the dose of the at-risk fungicide than to increasing the dose of the mixing partner. 3. Although there are very few studies, the existing evidence suggests that mixing two at-risk fungicides is also a useful resistance management tactic. The aspects that have received too little attention to draw generic conclusions about the effectiveness of fungicide mixtures as resistance management strategies are as follows: (i) the relative effect of the dose of the two mixing partners on selection for fungicide resistance, (ii) the effect of mixing on the effective life of a fungicide (the time from introduction of the fungicide mode of action to the time point where the fungicide can no longer maintain effective disease control), (iii) polygenically determined resistance, (iv) mixtures of two at-risk fungicides, (v) the emergence phase of resistance evolution and the effects of mixtures during this phase, and (vi) monocyclic diseases and nonfoliar diseases. The lack of studies on these aspects of mixture use of fungicides should be a warning against overinterpreting the findings in this review.
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Reimann, Sven, and Holger B. Deising. "Inhibition of Efflux Transporter-Mediated Fungicide Resistance in Pyrenophora tritici-repentis by a Derivative of 4′-Hydroxyflavone and Enhancement of Fungicide Activity." Applied and Environmental Microbiology 71, no. 6 (June 2005): 3269–75. http://dx.doi.org/10.1128/aem.71.6.3269-3275.2005.
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ABSTRACT Populations of the causal agent of wheat tan spot, Pyrenophora tritici-repentis, that are collected from fields frequently treated with reduced fungicide concentrations have reduced sensitivity to strobilurin fungicides and azole fungicides (C14-demethylase inhibitors). Energy-dependent efflux transporter activity can be induced under field conditions and after in vitro application of sublethal amounts of fungicides. Efflux transporters can mediate cross-resistance to a number of fungicides that belong to different chemical classes and have different modes of action. Resistant isolates can grow on substrata amended with fungicides and can infect plants treated with fungicides at levels above recommended field concentrations. We identified the hydroxyflavone derivative 2-(4-ethoxy-phenyl)-chromen-4-one as a potent inhibitor of energy-dependent fungicide efflux transporters in P. tritici-repentis. Application of this compound in combination with fungicides shifted fungicide-resistant P. tritici-repentis isolates back to normal sensitivity levels and prevented infection of wheat leaves. These results highlight the role of energy-dependent efflux transporters in fungicide resistance and could enable a novel disease management strategy based on the inhibition of fungicide efflux to be developed.
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Yellareddygari, S. K. R., Julie S. Pasche, Raymond J. Taylor, and Neil C. Gudmestad. "Individual Participant Data Meta-Analysis of Foliar Fungicides Applied for Potato Early Blight Management." Plant Disease 100, no. 1 (January 2016): 200–206. http://dx.doi.org/10.1094/pdis-05-15-0530-re.
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Foliar fungicides continue to be the primary means of early blight management on potato in the United States. Both premium-priced, single-site mode-of-action “specialty” fungicides and standard protectant multisite fungicides are applied, either alone or incorporated into fungicide rotation programs to combat early blight. Individual participant data meta-analysis was conducted to compare overall fungicide efficacy against early blight on potato, quantify tuber yields, and identify the most efficacious timing for fungicide applications. In this study, the specialty fungicide-based applications were compared against the standard fungicides chlorothalonil and mancozeb applied alone. Type 3 fixed effects indicated that there was a significant difference (P < 0.0001) in overall efficacy and yield among the treatments applied to manage early blight in potato. There was a significant difference (P < 0.0001) among treatments in early blight development during the growing season. Applications incorporating specialty fungicides, when compared with standard fungicides, significantly affected disease severity from vegetative growth initiation (P = 0.0139) to tuber maturation (P = 0.0009). Results demonstrate that the higher cost, specialty-fungicide-based applications were most effective for early blight management in North Dakota and Minnesota.
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Yellareddygari, S. K. R., Raymond J. Taylor, Julie S. Pasche, and Neil C. Gudmestad. "Quantifying Control Efficacy of Fungicides Commonly Applied for Potato Early Blight Management." Plant Disease 103, no. 11 (November 2019): 2821–24. http://dx.doi.org/10.1094/pdis-03-19-0670-re.
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Early blight is an economically important foliar disease of potato in the United States. Because of the lack of resistant potato cultivars, fungicides are applied extensively to obtain adequate control. To manage early blight, standard protectant fungicides and single-site mode-of-action “specialty” fungicides are applied either alone or incorporated into a fungicide rotation program. Control efficacy at two crop growth stages (tuber initiation/early bulking and late bulking/tuber maturation) and the overall tuber yield response to standard and specialty fungicides were assessed using network metaanalytic models. Control efficacy of fungicides ranged from moderate to very high (>30 to 75%) compared with the nontreated control. For both potato growth stages, specialty fungicides performed better than standard protectant fungicides. Furthermore, control efficacy of both fungicides was higher (3 to 9%) at late bulking and tuber maturation when compared with early bulking crop growth stage. Specialty fungicide programs increased overall tuber yields by 4 and 9% over standard fungicides and nontreated control, respectively. Based on the results, more precise fungicide use recommendations and fungicide programs can be developed for early blight management.
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Jarmołkowicz, Joanna K., and Jacek Olszewski. "Gas exchange parameters in leaves and ears of winter wheat Tricitum aestivum L. and its productivity under fungicide control conditions." Acta Agrobotanica 63, no. 2 (2012): 135–47. http://dx.doi.org/10.5586/aa.2010.041.
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A research experiment was conducted in which rates of photosynthesis and transpiration were measured in leaves and ears of two winter wheat varieties grown under fungicide control conditions and without fungicide control. A LI-COR 6400 portable gas exchange system was used in the investigations. In most cases the fungicide Juwel was shown to have no effect on the gas exchange processes, whereas the other of the fungicidal agents applied - Swing - significantly decreased the gas exchange rates measured. Measurements of gas exchange parameters in ears showed that the intensity of gas exchange was low, in particular at the later stage of ear development. But the applied fungicide caused higher release of CO<sub>2</sub> into the atmosphere than its uptake. Furthermore, the applied fungicides were found to significantly increase grain yield compared to the control treatment, both in the first and second year of the study. Among the tested varieties, 'Nutka' was characterized by higher productivity, in spite of lower 1000 kernel weight. However, this cultivar developed longer ears with a larger amount of grains.
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LaMondia, J. A. "Management of Euonymus Anthracnose and Fungicide Resistance in Colletotrichum gloeosporioides by Alternating or Mixing Fungicides." Journal of Environmental Horticulture 19, no. 1 (March 1, 2001): 51–55. http://dx.doi.org/10.24266/0738-2898-19.1.51.
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Abstract Fungicidal management of anthracnose leaf spot of euonymus (Euonymus fortunei ‘Emerald 'n Gold’ or ‘Emerald Gaiety’), caused by Colletotrichum gloeosporioides, was examined. Fungicide resistance was present in the pathogen population. Weekly applications to foliage for 12 weeks to the same plants in 1997 and 1998 of: thiophanate-methyl alone; or thiophanate-methyl, chlorothalonil, ethylenebis-dithiocarbamate and copper applied sequentially; or mixtures of thiophanate-methyl plus chlorothalonil alternated weekly with thiophanate-methyl plus ethylene-bis-dithiocarbamate were applied. Applications of the same treatments, azoxystrobin, or each of the above fungicides alone were applied at biweekly intervals in 1999. Unsprayed plants served as controls. Percent defoliation was lowest for fungicide mixtures (thiophanate-methyl plus chlorothalonil alternated with thiophanate-methyl plus ethylene-bis-dithiocarbamate) and was highest for unsprayed controls and plants treated with thiophanate-methyl alone. The average number of lesions per 100 leaves was lower for mixed and sequential fungicide programs than for untreated or thiophanate-methyl alone spray programs. Emerald 'n Gold had more lesions per leaf than Emerald Gaiety, but the level of defoliation was greater for Emerald Gaiety. Fungicide-resistant C. gloeosporioides isolates, which were recovered on media amended with thiophanate-methyl or with chlorothalonil, were in lowest frequency from plants treated with the mixed fungicide program. Management of euonymus anthracnose and fungicide resistance in C. gloeosporioides may be achieved by applying fungicide mixtures with different modes of action.
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Warneke, Brent, Lindsey D. Thiessen, and Walter F. Mahaffee. "Effect of Fungicide Mobility and Application Timing on the Management of Grape Powdery Mildew." Plant Disease 104, no. 4 (April 2020): 1167–74. http://dx.doi.org/10.1094/pdis-06-19-1285-re.
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Grape powdery mildew (GPM) fungicide programs consist of 5 to 15 applications, depending on region or market, in an attempt to achieve the high fruit quality standards demanded by the market. Understanding how fungicides redistribute and targeting redistributing fungicide to critical crop phenological stages could improve fungicide protection of grape clusters. This study evaluated fungicide redistribution in grapevines from major fungicide groups labeled for GPM control. Translaminar and xylem redistribution was examined by placing fungicide-impregnated filter disks on the adaxial or abaxial leaf surface of detached leaves for 10 min and then incubating for 48 h before inoculating the abaxial surface with conidia. Vapor redistribution used Teflon disks sprayed with fungicides and placed on the abaxial leaf surface of detached leaves 48 h before inoculation. Disease development was rated 10 days later. Translaminar movement through calyptra was tested using flowering potted vines. All fungicides tested redistributed through at least one mechanism. Fungicide timing at critical phenological stages (early, mid, and late bloom) was assessed in small plots of cultivar Pinot noir vines. The application of trifloxystrobin, quinoxyfen, or fluopyram at different bloom stages showed that applications initiated at end of bloom resulted in the lowest berry infection probabilities of 0.073, 0.097, and 0.020, respectively. The results of this study suggest that integrating two carefully timed applications of redistributing fungicides initiated at end of bloom into a fungicide program may be an effective strategy for wine grape growers in western Oregon to produce fruit with low GPM infection.
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Sonah, Humira, Rupesh K. Deshmukh, and Anil S. Kotasthane. "Fungicidal Interference during Infection Related Developmental Stages in Magnaporthe grisea." International Journal of Phytopathology 1, no. 1 (December 15, 2012): 49–55. http://dx.doi.org/10.33687/phytopath.001.01.0015.
Full textAbstract:
Rice blast, a serious epidemic disease that limits grain yield worldwide is caused by fungal pathogen Magnaporthe grisea. The present investigation was carried out to identify the probable avenues of interference by different fungicides during the critical stages of infection related morphogenesis of M. grisea. Effect of six fungicides at different stages of infection related morphogenesis showed variable results like interference in conidial germination, distortion of surface structure of the spores, interference in the germ tube elongation, interference in the transfer of the cell contents from spore to appresorrium, deformity in appressorial dome, interference in the melanin deposition. We speculate the critical stages at which these fungicides may interfere. The activity of immunosuppressive drug cyclosporin A (CsA) which is a potential antifungal agent was equated with all the fungicides used. We hypothesize that the exposure of the M. grisea spore to the fungicide may lead to the formation of a cyclophilin CYP1-fungicide complex, which inactivates calcineurin and prevents calcium/ calmodulin-dependent protein phosphatase signaling and is therefore one of the target of fungicidal interference. An understanding of how fungal pathogens break the protective barrier that comprise the surface of the host plant as well as precise identification of avenues of fungicidal interference during infection related development in M. grisea will lead to novel approach for controlling plant diseases.
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Berdugo, Carlos Andres, Anne-Katrin Mahlein, Ulrike Steiner, Heinz-Wilhelm Dehne, and Erich-Christian Oerke. "Sensors and imaging techniques for the assessment of the delay of wheat senescence induced by fungicides." Functional Plant Biology 40, no. 7 (2013): 677. http://dx.doi.org/10.1071/fp12351.
Full textAbstract:
Near-range and remote sensing techniques are excellent alternatives to destructive methods for measuring beneficial effects of fungicides on plant physiology. Different noninvasive sensors and imaging techniques have been used and compared to measure the effects of three fungicidal compounds (bixafen, fluoxastrobin and prothioconazole) on wheat (Triticum aestivum L.) physiology under disease-free conditions in the greenhouse. Depending on the fungicidal treatment, changes in green leaf area and yield parameters were observed. Chlorophyll fluorescence of leaves was useful for measuring differences in the effective quantum yield of PSII. Reflectance measurements of wheat leaves were highly sensitive to changes in plant vitality. The spectral vegetation indices were useful for determining the differences among treatments in terms of leaf senescence, pigments and water content. The analysis of ear and leaf surface temperature was reliable for detecting effects of fungicides on plant senescence. Using nondestructive sensors, it was possible to assess a delay in senescence of wheat due to fungicide application. Furthermore, it was deduced that sensors and imaging methods are useful tools to estimate the effects of fungicides on wheat physiology. Physiological parameters measured by the sensors were actually more sensitive than yield parameters to assess the effect caused by fungicide application on wheat physiology.
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Rachman, Fai, Ellen Rosyelina Sasmita, and Suyadi Wongsowijoyo. "Pengaruh Pencucian Benih dengan Penambahan Fungisida terhadap Tingkat Serangan Penyakit Bulai, Pertumbuhan, dan Hasil Jagung Hibrida Varietas P27." Agrosains: Jurnal Penelitian Agronomi 21, no. 1 (March 26, 2019): 16. http://dx.doi.org/10.20961/agsjpa.v21i1.28348.
Full textAbstract:
Corn is an important food crop in the world. Downy mildew as a corn main disease causes a decrease of crop yields. Downy mildew can be prevented by seed treatment. The study aims to determine the effect of washing and adding fungicides on seeds to downy mildew attack, growth, and hybrid corn yields. The research conducted in Wedomartani Experimental Field, Ngemplak, Sleman with experiment in June – October 2018. Field experiment with Randomized Complete Block Design (RCBD) was set up, using single factor, which is seeds of P27 variety washed and added fungicides. There are 10 treatments: control, washed seeds, washed seeds + fungicide metalaxyl 3g/kg + dimetomorph 2g/kg, washed seeds + fungicide metalaxyl 3g/kg + dimetomorph 3g/kg, washed seeds + fungicide metalaxyl 3g/kg + dimetomorph 4g/kg, washed seeds + fungicide metalaxyl 3g/kg + dimetomorph 5g/kg, washed seeds + fungicide metalaxyl 5g/kg + dimetomorph 2g/kg, washed seeds + fungicide metalaxyl 5g/kg + dimetomorph 3g/kg, washed seeds + fungicide metalaxyl 5g/kg + dimetomorph 4g/kg, washed seeds + fungicide metalaxyl 5g/kg + dimetomorph 5g/kg. The results showed that control effective to prevent downy mildew attack, increasing growth and hybrid corn yields. Washed seeds cause high level of downy mildew attack, slow growth, and low crop yields. Seed treatments with fungicides is not effective, because give same affect with control.
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Nuwamanya, Andrew M., Steven Runo, and Maina Mwangi. "Farmers’ perceptions on tomato early blight, fungicide use factors and awareness of fungicide resistance: Insights from a field survey in Kenya." PLOS ONE 18, no. 1 (January 23, 2023): e0269035. http://dx.doi.org/10.1371/journal.pone.0269035.
Full textAbstract:
Early blight (EB) caused by Alternaria solani is one of the most devastating tomato diseases in Kenya and is most often managed by application of synthetic fungicides. However, there have been reports from farmers about the declining efficacy of some fungicides. These reports suggest that A. solani populations in Kenya could be developing resistance to some of the commonly used fungicides. In this study, we surveyed 175 tomato fields, sampled in 3 major tomato producing counties in Kenya, to determine the status of EB, management practices, and fungicide use factors that could contribute to development of resistance to fungicides among A. solani populations in Kenya. Data was recorded on farm characteristics, EB prevalence, fungicide usage, and farmers’ perceptions on fungicide efficacy. EB was prevalent in 85% of the fields and 90% of the farmers identified it as a major cause of yield loss. Tomato was grown all year round on 60% of the fields with only short fallow periods. All farmers reported that they were relying on fungicides for EB control and none among the cultivars grown was resistant to the disease. A total of 40 fungicide products, representing 20 active compounds with varying FRAC resistance risk levels were in use against EB. Majority (83%) of the farmers were applying fungicides at dosages and frequencies higher than those indicated on labels. Most farmers (81%) indicated that they had observed declines in effectiveness of at least one fungicide, used at EB control. This observation was more with fungicides in the strobilurin and triazole groups. These findings demonstrate that the current tomato production systems in Kenya do not take into account the risk of A. solani developing resistance to fungicides. Enhancing farmers’ knowledge of the disease and their ability to properly select and apply fungicides is therefore crucial for effective control of EB and mitigating the high risk of fungicide resistance build up.
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Kanetis, Loukas, Helga Förster, and James E. Adaskaveg. "Comparative Efficacy of the New Postharvest Fungicides Azoxystrobin, Fludioxonil, and Pyrimethanil for Managing Citrus Green Mold." Plant Disease 91, no. 11 (November 2007): 1502–11. http://dx.doi.org/10.1094/pdis-91-11-1502.
Full textAbstract:
Three new fungicides (i.e., azoxystrobin, fludioxonil, and pyrimethanil) are currently being introduced for postharvest management of citrus green mold in the United States. The effectiveness of each fungicide was evaluated when applied alone (at 1,000 to 1,200 mg/liter) or in mixtures (at 500 mg/liter each component) to lemon fruit that were wound-inoculated with imazalil/thiabendazole (TBZ)-sensitive or -resistant isolates of Penicillium digitatum. In laboratory studies when aqueous fungicide solutions were applied 9 to 21 h after inoculation, pyrimethanil showed the highest level of green mold control. The efficacy of fludioxonil and azoxystrobin was very high at the early timings, but decreased as time after inoculation increased. Differences in fungicide performance were not due to multiple fungicide resistance, but more likely due to differences in fungicide mobility in fruit tissue. Azoxystrobin-fludioxonil mixtures were significantly more effective when compared to single-fungicide treatments. Mixtures of imazalil with pyrimethanil were the most effective in controlling decay. The efficacy of all fungicides was significantly lower when mixed into a packing fruit coating as compared to aqueous or storage fruit coating applications. In laboratory and packingline studies, the lowest incidence of green mold decay was obtained when azoxystrobin-fludioxonil and imazalil-pyrimethanil were applied as aqueous solutions that were followed by a fruit coating. Among the new fungicides, azoxystrobin and fludioxonil applied in water or storage fruit coating, respectively, provided the best anti-sporulation activity. Storage fruit coating improved the activity of both fungicides. Pyrimethanil was the least effective fungicide in suppressing sporulation of the pathogen on decaying fruit. Overall, among the mixtures, azoxystrobin-fludioxonil and TBZ-fludioxonil had high anti-sporulation activity in aqueous and storage fruit coating applications. New integrated management programs should be based on monitoring of fungicide sensitivities in pathogen populations, rotating mixtures of products with different modes of action, and using appropriate fungicide application strategies.
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Błaszkowski, Janusz. "Bffects of foliar fungicides on the mycoflora of glumes of Triticum aestivum." Acta Mycologica 30, no. 1 (August 20, 2014): 41–48. http://dx.doi.org/10.5586/am.1995.004.
Full textAbstract:
In the years 1983-1984. the effect of three foliar fungicides, i.e.. Bayleton 25 WP. Dithane M-45 and Funaben K on the mycoflora associated with glumus of spring <i>Tritieum aestivum</i> cv. Kolibri cultivated in the field was investigated. During each vegetative period, glumes were collected in the milky ripe of seeds. Fungi species associated with glumes were determined based of colonies isolated from glumes incubated in Petri dishes with potato glucose agar. The fungicide which reduced the most the overall number of fungal isolates was Bayleton 25 WP. The number of species was most reduced following Dithane M-45 application. The mycoflora of glumes which had been untreated and treated with fungicides was compared with fungicides-treated and fungicide-untreated seeds and leaves. The highest similarity in the mycoflora of fungicide-untreated plant parts was found when glumes and seeds were compared. The mycoflora of fungicide-treated glumes, leaves, and seeds varied. depending on the year and fungicide applied.
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Van de Wouw, A. P., J. L. Scanlan, S. J. Marcroft, A. J. Smith, E. M. Sheedy, N. W. Perndt, C. E. Harrison, L. M. Forsyth, and A. Idnurm. "Fungicide sensitivity and resistance in the blackleg fungus, Leptosphaeria maculans, across canola growing regions in Australia." Crop and Pasture Science 72, no. 12 (2021): 994. http://dx.doi.org/10.1071/cp21369.
Full textAbstract:
Fungicide use has become a fundamental part of many crop protection systems around the world, including to control blackleg disease on canola (Brassica napus L.). In Australia, most canola growers routinely apply at least one fungicide, and potentially multiple fungicides with different modes of action, in a single growing season. There is evidence for the emergence of fungicide resistance in Leptosphaeria maculans, the causal agent of blackleg disease, to the demethylation inhibitor (DMI) class of fungicides in Australia. However, it is not known whether resistance exists towards other chemical classes such as the succinate dehydrogenase inhibitors (SDHI). In this work, 397 samples were screened for resistance towards seven fungicide treatments in stubble-borne L. maculans populations collected from eight canola-growing agro-ecological regions of Australia from 2018 to 2020, a time frame that bridges the introduction of new chemicals for blackleg control. We confirmed that DMI resistance in L. maculans is pervasive across all of the sampled canola-growing regions, with 15% of fungal populations displaying high levels (resistance scores >0.5) of resistance towards the DMI fungicides. Although resistance to newly introduced SDHI fungicides was low, we found evidence of positive cross-resistance between established DMI-only fungicides and a newly introduced combined DMI and quinone outside inhibitor fungicide, suggesting that the efficacy of the latter may be limited by widespread DMI resistance. Proactive surveillance, as performed here, may provide a means to avoid the rapid loss of fungicide efficacy in the field.
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Huang, Xiaoqing, Xina Wang, Fanfang Kong, Theo van der Lee, Zhongyue Wang, and Hao Zhang. "Detection and Characterization of Carboxylic Acid Amide-Resistant Plasmopara viticola in China Using a TaqMan-MGB Real-Time PCR." Plant Disease 104, no. 9 (September 2020): 2338–45. http://dx.doi.org/10.1094/pdis-02-20-0291-re.
Full textAbstract:
Grape production is increasing globally and so are problems with downy mildew, one of the main constraints in grape production. Downy mildew on grape is caused by Plasmopara viticola, an obligate biotrophic pathogen belonging to the oomycetes. Control of the disease is usually performed by fungicide applications, of which carboxylic acid amide (CAA) fungicides represent one of the most widely used groups of fungicides. Our previous research showed that the extensive application of CAA fungicides can result in fungicide resistance and in China, CAA-resistant isolates of P. viticola were collected from the field in 2014. To monitor the distribution and spread of CAA fungicide resistance, we developed a TaqMan-minor groove binder (MGB) real-time PCR-based method designed on a functional mutation in the PvCesA3 gene that allows efficient identification of CAA fungicide resistant and sensitive genotypes. The assay was validated on 50 isolates using Sanger sequencing and fungicide bioassays and exploited in a comprehensive survey comprising 2,227 single-sporangiophore isolates from eight major grapevine regions in China. We demonstrate that CAA fungicide resistance in P. viticola is widespread in China. On average, 53.3% of the isolates were found to be resistant, but marked differences were found between locations with percentages of resistant isolates varying from 0.3 to 96.6%. Furthermore, the frequency of CAA-resistant isolates was found to be significantly correlated with the exposure to CAA fungicides (P < 0.05). We further discussed the possibilities to apply the TaqMan-MGB real-time PCR assay to assess the frequency of fungicide-resistant P. viticola isolates in each region or vineyard, which would facilitate the correct choice of fungicide for grape downy mildew and resistance management strategies.
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Cosseboom, Scott D., Kelly L. Ivors, Guido Schnabel, Patricia K. Bryson, and Gerald J. Holmes. "Within-Season Shift in Fungicide Resistance Profiles of Botrytis cinerea in California Strawberry Fields." Plant Disease 103, no. 1 (January 2019): 59–64. http://dx.doi.org/10.1094/pdis-03-18-0406-re.
Full textAbstract:
Sensitivity of Botrytis cinerea to seven fungicide chemical classes was determined for 888 isolates collected in 2016 from 47 California strawberry fields. Isolates were collected early season (minimum fungicide exposure) and late season (maximum fungicide exposure) from the same planting block in each field. Resistance was determined using a mycelial growth assay, and variable frequencies of resistance were observed to each fungicide at both sampling times (early season %, late season %): boscalid (12, 35), cyprodinil (12, 46), fenhexamid (53, 91), fludioxonil (1, 4), fluopyram (2, 7), iprodione (25, 8), isofetamid (0, 1), penthiopyrad (8, 25), pyraclostrobin (77, 98), and thiophanate-methyl (81, 96). Analysis of number of chemical class resistances (CCRs) revealed an increasing shift in CCR from the early to late season. Phenotypes of 40 isolates that were resistant or sensitive to different chemical classes were associated with presence or absence of mutations in target genes. Fungicide-resistance phenotypes determined in the mycelial growth assay closely matched (93.8%) the genotype observed. Previously described resistance-conferring mutations were found for each gene. A survey of fungicide use from 32 of the sampled fields revealed an average of 15 applications of gray mold–labeled fungicides per season at an average interval of 12 days. The most frequently applied fungicides (average number of applications during the 2016 season) were captan (7.3), pyraclostrobin (2.5), cyprodinil (2.3), fludioxonil (2.3), boscalid (1.8), and fenhexamid (1.4). Multifungicide resistance is widespread in California. Resistance management tactics that reduce selection pressure by limiting fungicide use, rotating among Fungicide Resistance Action Committee codes, and mixing/rotating site-specific fungicides with multisite fungicides need to be improved and implemented.
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Wyenandt, Christian A., Nancy Maxwell, and Daniel L. Ward. "Fungicide Programs Affect ‘Practical’ Resistance Development in Cucurbit Powdery Mildew of Pumpkin." HortScience 43, no. 6 (October 2008): 1838–45. http://dx.doi.org/10.21273/hortsci.43.6.1838.
Full textAbstract:
The effects of two pumpkin cultivars and five fungicide programs on cucurbit powdery mildew development and yield were evaluated in southern New Jersey from 2005 to 2007. Each year, five separate fungicide programs were applied to powdery mildew-tolerant cv. Magic Lantern or powdery mildew-susceptible cv. Howden pumpkin. The five fungicide programs applied season-long (10 applications per program) included: 1) protectant fungicides only: manzate + sulfur [Fungicide Resistance Action Committee (FRAC) codes M3 + M2] alternated weekly with maneb + copper hydroxide (FRAC codes M3 + M1); 2) standard program: chlorothalonil + myclobutanil (FRAC codes M5 + 3) alternated with azoxystrobin (FRAC code 11); 3) intensive program: maneb + myclobutanil (FRAC codes M3 + 3) alternated with [famoxadone + cymoxanil] (FRAC codes 11 + 27); 4) FRAC code 3 weekly: chlorothalonil + myclobutanil (FRAC codes M5 + 3) alternated with myclobutanil (FRAC code 3); and 5) FRAC code 11 weekly: chlorothalonil + azoxystrobin (FRAC codes M5 + 11) alternated with azoxystrobin (FRAC code 11). In each year, there were no significant interactions between the fungicide program and cultivar. In each year, area under disease progress curve values were highest when a FRAC code 11 fungicide was applied weekly compared with a FRAC code 11 fungicide applied in a weekly rotation with a FRAC code 3 fungicide or a FRAC code 3 fungicide applied weekly. Visual examination of leaves at the end of each production season revealed there were no significant differences in powdery mildew development on the top (adaxial) or bottom (abaxial) sides of leaves in untreated subplots. Powdery mildew development was lower on the bottom sides of leaves when a Fungicide Resistance Action Committee (FRAC) code 3 fungicide was applied weekly compared with a FRAC code 11 fungicide applied weekly or when a FRAC code 3 fungicide was rotated weekly with a FRAC code 11 fungicide in each year of the study. There were no significant differences in total number of harvested fruit, number of harvested orange fruit, average weight of orange fruit, or percentage of harvested orange fruit between fungicide programs in each year of the study. Results of this study, based on arcsine-transformed area under disease progress curve (AUDPC) values and top and bottom leaf surface ratings, suggest that the weekly use of the FRAC code 11 fungicide lead to the development of practical resistance in the field population of cucurbit powdery mildew. Rotating a FRAC code 11 and FRAC code 3 fungicide weekly resulted in lower AUDPC values and powdery mildew development on the bottom side of leaves in 2 of 3 years of this study. However, based on AUPDC values and leaf rating values, the level of control obtained with the high-risk FRAC code 3 fungicide was less during each consecutive year. The immediate erosion of control (i.e., qualitative resistance) as observed with the FRAC code 11 fungicide or the gradual decline of control (quantitative resistance) as observed with the FRAC code 3 fungicide over three growing seasons shows the importance of being able to detect and understand the mechanisms of practical resistance development. This understanding will allow appropriate fungicide control recommendations to be made in a timely (i.e., real-time) manner. Importantly, fungicide resistance is most likely to develop on the bottom side (abaxial) of pumpkin leaves when effective, low-risk (nonmobile) fungicides (FRAC code M numbers) are tank-mixed with high-risk fungicides in cucurbit powdery mildew control programs. Tank-mixing fungicides that have a high risk for resistance development with protectant fungicides that have a low risk for resistance development remains critically important when controlling cucurbit powdery mildew and reducing the potential for fungicide resistance development. This is the first report of cucurbit powdery mildew developing practical resistance to a FRAC code 11 and FRAC code 3 fungicide in New Jersey.
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Manning, Paul, Krilen Ramanaidu, and G. Christopher Cutler. "Honey bee survival is affected by interactions between field-relevant rates of fungicides and insecticides used in apple and blueberry production." FACETS 2, no. 2 (September 1, 2017): 910–18. http://dx.doi.org/10.1139/facets-2017-0025.
Full textAbstract:
Certain compounds of low toxicity can increase the susceptibility of an organism to toxic substances; this is known as potentiation. Demethylation inhibiting (DMI) fungicides can potentiate insecticides by impairing the production of detoxification enzymes. As both DMI fungicides and insecticides can be used near or during crop bloom, the combination may be hazardous if exposed to pollinators. Using pesticides used in blueberry or apple production, we conducted laboratory bioassays to test how combinations of field-relevant concentrations of DMI fungicides and insecticides affected honey bee ( Apis mellifera) survival. We found propiconazole, a DMI fungicide, potentiated the toxicity of the neonicotinoid insecticide acetamiprid. We found no evidence of propiconazole potentiating field-relevant concentrations of the spinosyn insecticide spinetoram. We also found that the DMI fungicide flusilazole potentiated spinetoram but not acetamiprid. A fungicidal formulation combining pyraclostrobin and boscalid did not potentiate either insecticide. Given that bees can be simultaneously exposed to multiple pesticides, understanding the potential of pesticide potentiation and synergism may help mitigate risks associated with pollinator exposure to pesticides.
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Twizeyimana, M., and G. L. Hartman. "Sensitivity of Phakopsora pachyrhizi Isolates to Fungicides and Reduction of Fungal Infection Based on Fungicide and Timing of Application." Plant Disease 101, no. 1 (January 2017): 121–28. http://dx.doi.org/10.1094/pdis-04-16-0552-re.
Full textAbstract:
Soybean rust (SBR), caused by Phakopsora pachyrhizi, is a damaging foliar fungal disease in many soybean-growing areas of the world. Strategies to manage SBR include the use of foliar fungicides. Fungicide types, the rate of product application, and the number and timing of applications are critical components for successful rust management. The objectives of this study were to determine i) the sensitivity of P. pachyrhizi isolates collected in the U.S. to a range of fungicides and ii) the reduction of fungal infection based on fungicide type and timing of applications on soybean. There were differences (P < 0.05) in effective concentration (EC50) values among the fungicides tested. Azoxystrobin had low EC50 values for both urediniospore germination and fungal sporulation on inoculated leaflets. There were differences (P < 0.05) in fungal sporulation for application times, fungicide treatments, and their interaction when the fungus was inoculated on plants. All application times and nearly all fungicide treatments reduced (α = 0.05) fungal infection compared with the nonfungicide control. Information on fungicide sensitivity of P. pachyrhizi isolates and the preventive and curative effects of different fungicides are important in the management of SBR.
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Hobbelen, P. H. F., N. D. Paveley, and F. van den Bosch. "Delaying Selection for Fungicide Insensitivity by Mixing Fungicides at a Low and High Risk of Resistance Development: A Modeling Analysis." Phytopathology® 101, no. 10 (October 2011): 1224–33. http://dx.doi.org/10.1094/phyto-10-10-0290.
Full textAbstract:
This study used mathematical modeling to predict whether mixtures of a high-resistance-risk and a low-risk fungicide delay selection for resistance against the high-risk fungicide. We used the winter wheat and Mycosphaerella graminicola host–pathogen system as an example, with a quinone outside inhibitor fungicide as the high-risk and chlorothalonil as the low-risk fungicide. The usefulness of the mixing strategy was measured as the “effective life”: the number of seasons that the disease-induced reduction of the integral of canopy green area index during the yield forming period could be kept <5%. We determined effective lives for strategies in which the dose rate (i) was constant for both the low-risk and high-risk fungicides, (ii) was constant for the low-risk fungicide but could increase for the high-risk fungicide, and (iii) was adjusted for both fungicides but their ratio in the mixture was fixed. The effective life was highest when applying the full label-recommended dose of the low-risk fungicide and adjusting the dose of the high-risk fungicide each season to the level required to maintain effective control. This strategy resulted in a predicted effective life of ≤12 years compared with 3 to 4 years when using the high risk fungicide alone.
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Peever, Tobin L., and Michael G. Milgroom. "Fungicide Resistance—Lessons for Herbicide Resistance Management?" Weed Technology 9, no. 4 (December 1995): 840–49. http://dx.doi.org/10.1017/s0890037x00024313.
Full textAbstract:
Resistance to agricultural fungicides has increaséd dramatically in the past twenty years, following the introduction of systemic fungicides. Disease control failures associated with fungicide resistance have occurred with many classes of fungicides and in many genera of plant-pathogenic fungi. In some cases, resistance evolved extremely rapidly making the chemicals ineffective for disease control only a few years after they were introduced.The rapid development of resistance to systemic fungicides has led to efforts to develop strategies to avoid or delay the evolution of fungicide resistance in plant pathogen populations. Despite a widespread interest in managing fungicide resistance, very few experimental studies have been performed to elucidate the important factors controlling resistance development. Most fungicide resistance studies have consisted of anecdotal field observations which have rarely been followed up with experimentation. In order to understand what factors affect the evolution of resistance, and to use this information to design effective resistance management strategies, more experimental studies are required.
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Yan, Xiaojing, Shuning Chen, Wei Sun, Xiaoxin Zhou, Daibin Yang, Huizhu Yuan, and Daoquan Wang. "Primary Mode of Action of the Novel Sulfonamide Fungicide against Botrytis cinerea and Field Control Effect on Tomato Gray Mold." International Journal of Molecular Sciences 23, no. 3 (January 28, 2022): 1526. http://dx.doi.org/10.3390/ijms23031526.
Full textAbstract:
Botrytis cinerea is considered an important plant pathogen and is responsible for significant crop yield losses. With the frequent application of commercial fungicides, B. cinerea has developed resistance to many frequently used fungicides. Therefore, it is necessary to develop new kinds of fungicides with high activity and new modes of action to solve the increasingly serious problem of resistance. During our screening of fungicide candidates, one novel sulfonamide compound, N-(2-trifluoromethyl-4-chlorphenyl)-2-oxocyclohexyl sulfonamide (L13), has been found to exhibit good fungicidal activity against B. cinerea. In this work, the mode of action of L13 against B. cinerea and the field control effect on tomato gray mold was studied. L13 had good control against B. cinerea resistant to carbendazim, diethofencarb, and iprodione commercial fungicides in the pot culture experiments. SEM and TEM observations revealed that L13 could cause obvious morphological and cytological changes to B. cinerea, including excessive branching, irregular ramification or abnormal configuration, and the decomposition of cell wall and vacuole. L13 induced more significant electrolyte leakage from hyphae than procymidone as a positive control. L13 had only a minor effect on the oxygen consumption of intact mycelia, with 2.15% inhibition at 50 μg/mL. In two locations over 2 years, the field control effect of L13 against tomato gray mold reached 83% at a rate of 450 g ai ha−1, better than the commercial fungicide of iprodione. Moreover, toxicological tests demonstrated the low toxicological effect of L13. This research seeks to provide technical support and theoretical guidance for L13 to become a real commercial fungicide.
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Chapman, Kimberly S., George W. Sundin, and Janna L. Beckerman. "Identification of Resistance to Multiple Fungicides in Field Populations of Venturia inaequalis." Plant Disease 95, no. 8 (August 2011): 921–26. http://dx.doi.org/10.1094/pdis-12-10-0899.
Full textAbstract:
Venturia inaequalis, the causal agent of apple scab, is controlled primarily by fungicides. Long-term, extensive fungicide use has led to the development of resistance to multiple fungicides. To assess fungicide resistance, isolates of V. inaequalis were collected from Indiana and Michigan orchards. Single-spore derived isolates were evaluated by mycelium growth assays with previously determined discriminatory doses on media containing dodine, kresoxim-methyl, myclobutanil, or thiophanate-methyl. Of 195 isolates tested, 5.2, 0.7, 57.0, and 92.6% of isolates were found to be resistant to dodine, kresoxim-methyl, myclobutanil, and thiophanate-methyl, respectively. This is the first report of kresoxim-methyl field resistance in these states. Isolates resistant or shifted to a single fungicide were often found to have multiple fungicide resistance. Of all isolates tested, 38% were identified as resistant or shifted to two fungicides, and 12% were resistant or shifted to all four fungicides tested. No fitness penalty was found for isolates resistant to multiple fungicides based on a statistical analysis of mycelial growth and conidial production.
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Chechi, Amanda, Walter Boller, Carlos Alberto Forcelini, Rafael Roehrig, and Elias Zuchelli. "Leaf area, spray volumes and applicable quantities of fungicide during the protection period for control of Asian soybean rust." Summa Phytopathologica 44, no. 4 (December 2018): 326–31. http://dx.doi.org/10.1590/0100-5405/174517.
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ABSTRACT The purpose of this study was to check the influence of leaf area index, spray volumes and applicable quantities of fungicide during the protection period, and for control of Asian soybean rust. All tests were conducted in the field and in the laboratory between 2014 and 2016. The quantity of fungicide and the spray volume were varied in the application of fungicides on soybean plants with different leaf area index. Rainfall simulation tests were also carried out at different times after application of fungicide. The spray volume and application rate of fungicide should be adequately proportioned according to the leaf area index of the soybean cultivar. The closer to the time of application that the rain occurs, the lower the control obtained by applying the fungicide. The leaf area index, the fungicide application rates, and the spray volumes influenced the protection period of fungicides and the control of Asian soybean rust.
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Thomas, A., D. B. Langston, and K. L. Stevenson. "Baseline Sensitivity and Cross-Resistance to Succinate-Dehydrogenase-Inhibiting and Demethylation-Inhibiting Fungicides in Didymella bryoniae." Plant Disease 96, no. 7 (July 2012): 979–84. http://dx.doi.org/10.1094/pdis-09-11-0744-re.
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Didymella bryoniae, which causes gummy stem blight (GSB) of watermelon, has a history of developing resistance to fungicides, most recently the succinate-dehydrogenase-inhibiting (SDHI) fungicide boscalid. To facilitate fungicide resistance monitoring, baseline sensitivity distributions were established for demethylation-inhibiting (DMI) fungicides tebuconazole and difenoconazole and the SDHI fungicide penthiopyrad, and reestablished for the SDHI fungicide boscalid. In all, 71 isolates with no known prior exposure to SDHIs or DMIs were used to determine the effective concentration at which mycelial growth was inhibited by 50% (EC50). EC50 values for boscalid, penthiopyrad, tebuconazole, and difenoconazole were 0.018 to 0.064, 0.015 to 0.057, 0.062 to 0.385, and 0.018 to 0.048 μg/ml, with median values of 0.032, 0.026, 0.118, and 0.031 μg/ml, respectively. Significant positive correlations between the sensitivity to penthiopyrad and boscalid (P < 0.0001, r = 0.75) and between tebuconazole and difenoconazole (P < 0.0001, r = 0.59) indicate a potential for cross-resistance between chemically related fungicides. In 2009, 103 isolates from fungicidetreated watermelon fields were tested for sensitivity to boscalid and penthiopyrad using a discriminatory concentration of 3.0 μg/ml. Of the isolates tested, 82 were insensitive and 14 were sensitive to both fungicides. Because of the significant potential for cross-resistance between closely related fungicides, growers will be advised not to use both SDHIs or both DMIs successively in the same fungicide spray program.
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Wyenandt, Christian A., Wesley L. Kline, and Daniel L. Ward. "Effect of Fungicide Program on the Development of Downy Mildew in Three Cucurbit Crops in New Jersey." Plant Health Progress 18, no. 3 (January 1, 2017): 181–85. http://dx.doi.org/10.1094/php-04-17-0026-phm.
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From 2014 to 2016, five fungicide programs of varying fungicide efficacy were evaluated for the control of cucurbit downy mildew (Pseudoperonospora cubensis) on three different cucurbit crops at the Rutgers Agricultural Research and Extension Center (RAREC) in Bridgeton, NJ. The five fungicide programs were: (i) no fungicide input; (ii) low-input (chlorothalonil only); (iii) medium-input (protectant + 2 downy mildew-specific fungicides [Tanos, Curzate]); (iv) high-input (protectant + 2 downy mildew-specific fungicides [Ranman, Presidio]); or (v) high-input (protectant + 3 downy mildew-specific fungicides [Previcur Flex, Ranman, Zampro]). The three cucurbit crops were cucumber cv. Marketmore 76, zucchini cv. Reward (summer squash), and acorn squash cv. Taybelle (winter squash). In 2014, only cucumber was infected by the pathogen. In 2015 and 2016, all three cucurbit hosts were infected by downy mildew at varying severities suggesting that the P. cubensis population may have differed compared with 2014. In all three years control of downy mildew was significantly higher when downy mildew-specific fungicides were included in weekly rotations. In some years, no fungicides, broad-spectrum fungicides only, or fungicides with moderate or lower efficacy for downy mildew may provide adequate control on certain cucurbit crop species depending on the current cucurbit downy mildew pathogen population.
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Fraaije, Bart A., Sarah L. Atkins, Ricardo F. Santos, Steven J. Hanley, Jonathan S. West, and John A. Lucas. "Epidemiological Studies of Pan-Azole Resistant Aspergillus fumigatus Populations Sampled during Tulip Cultivation Show Clonal Expansion with Acquisition of Multi-Fungicide Resistance as Potential Driver." Microorganisms 9, no. 11 (November 18, 2021): 2379. http://dx.doi.org/10.3390/microorganisms9112379.
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Pan-azole resistant isolates are found in clinical and environmental Aspergillus fumigatus (Af) populations. Azole resistance can evolve in both settings, with Af directly targeted by antifungals in patients and, in the environment, Af unintendedly exposed to fungicides used for material preservation and plant disease control. Resistance to non-azole fungicides, including methyl benzimidazole carbamates (MBCs), quinone outside inhibitors (QoIs) and succinate dehydrogenase inhibitors (SDHIs), has recently been reported. These fungicide groups are not used in medicine but can play an important role in the further spread of pan-azole resistant genotypes. We investigated the multi-fungicide resistance status and the genetic diversity of Af populations sampled from tulip field soils, tulip peel waste and flower compost heaps using fungicide sensitivity testing and a range of genotyping tools, including STRAf typing and sequencing of fungicide resistant alleles. Two major clones were present in the tulip bulb population. Comparisons with clinical isolates and literature data revealed that several common clonal lineages of TR34/L98H and TR46/Y121F/T289A strains that have expanded successfully in the environment have also acquired resistance to MBC, QoI and/or SDHI fungicides. Strains carrying multiple fungicide resistant alleles have a competitive advantage in environments where residues of multiple fungicides belonging to different modes of action are present.
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Tjosvold, S. A., S. T. Koike, and D. L. Chambers. "Evaluation of Fungicides for the Control of Phytophthora ramorum Infecting Rhododendron, Camellia, Pieris, and Viburnum." Plant Health Progress 9, no. 1 (January 2008): 27. http://dx.doi.org/10.1094/php-2008-0208-01-rs.
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Fungicides were evaluated for pre- and post-infection control of ramorum blight, caused by Phytophthora ramorum, on Rhododendron cvs. Cunningham's White and Irish Lace, Camellia japonica, Pieris japonica, and Viburnum tinus. Cyazofamid, dimethomorph, mefenoxam, pyraclostrobin, and fenamidone applied as foliar sprays consistently provided preventative control as indicated by reduced lesion size compared to water controls. These fungicides provided preventative activity for at least 28 days in the tested species except in Rhododendron where fungicides were active for at least 14 days following application. With preventative fungicide applications, the pathogen was recovered from most fungicide-treated leaves by isolation onto selective media. Dimethomorph consistently reduced the percent recovery from diseased Rhododendron leaves. With post-infection treatments, the fungicides did not significantly reduce lesion growth and percent recovery of the pathogen. The pathogen was recovered from lesions consistently at least 6 weeks after fungicide application in Rhododendron regardless of treatment on intact and fallen diseased leaves. However, the cultures resulting from isolations of diseased tissue treated with cyazofamid and dimethomorph were significantly slower growing than those cultures from other fungicide treatments. P. ramorum management issues relating to fungicide use in commercial nurseries are discussed Accepted for publication 12 October 2007. Published 8 February 2008.
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Myresiotis, C. K., G. S. Karaoglanidis, and K. Tzavella-Klonari. "Resistance of Botrytis cinerea Isolates from Vegetable Crops to Anilinopyrimidine, Phenylpyrrole, Hydroxyanilide, Benzimidazole, and Dicarboximide Fungicides." Plant Disease 91, no. 4 (April 2007): 407–13. http://dx.doi.org/10.1094/pdis-91-4-0407.
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During February 2005, 55 single-spore isolates of Botrytis cinerea were collected at the end of the season from vegetable crops grown in 18 greenhouses on the island of Crete, Greece. They were tested for sensitivity to the anilinopyrimidine fungicides pyrimethanil and cyprodinil, the hydroxyanilide fungicide fenhexamid, the phenylpyrrole fungicide fludioxonil, the dicarboximide fungicide iprodione, and the benzimidazole fungicide carbendazim. Results of the study showed the existence of benzimidazole- and dicarboximide-resistant strains at frequencies of 61.8 and 18%, respectively. Moreover, for first time, the development of resistance to anilinopyrimidine fungicides by B. cinerea was detected in greenhouse vegetable crops on the island of Crete. High resistance frequencies of 49.1 and 57.4% were observed for pyrimethanil and cyprodinil, respectively. In addition, one isolate was found to be resistant to the hydroxyanilide fungicide fenhexamid, while no strains resistant to the phenylpyrrole fungicide were detected. Among the 55 isolates tested, 13 were resistant only to carbendazim, 6 were resistant only to anilinopyrimidines, 3 were resistant to both benzimidazoles and dicarboximides, 17 were resistant to both benzimidazoles and anilinopyrimidines, 6 were resistant to both dicarboximides and anilinopyrimidines, 1 was simultaneously resistant to benzimidazoles, dicarboximides, and anilinopyrimidines, 1 was resistant to both anilinopyrimidines and hydroxyanilides, and 8 were sensitive to all fungicides tested. A strong cross-resistance relationship was found between the two anilinopyrimidine fungicides tested when log transformed EC50 values of the isolates were subjected to a linear regression analysis (r = 0.71). Despite the detection of several phenotypes with simultaneous resistance to chemically unrelated active ingredients, in none of the remaining possible fungicide pairs was there observed any kind of cross-resistance relationship.
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Delvalle, Tanner C., Peter J. Landschoot, and John E. Kaminski. "Effects of Dew Removal and Mowing Frequency on Fungicide Performance for Dollar Spot Control." Plant Disease 95, no. 11 (November 2011): 1427–32. http://dx.doi.org/10.1094/pdis-12-10-0941.
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Dollar spot (Sclerotinia homoeocarpa) is a severe disease problem on creeping bentgrass (Agrostis stolonifera) fairways. The objective of this study was to evaluate the effects of dew removal and mowing frequency on fungicide performance for dollar spot control. In 2009 and 2010, an experiment involving daily dew removal or no dew removal, mowing frequency (2, 4, and 6 days week–1), and fungicides (chlorothalonil, propiconazole, and iprodione) was conducted on creeping bentgrass maintained as a fairway. Daily dew removal resulted in fewer dollar spot infection centers (IC) compared with not removing dew during late summer 2009 and 2010 for all mowing-frequency and fungicide treatments. As mowing frequency increased from 2 to 6 days week–1, dollar spot IC decreased when averaged across all fungicide treatments. For all fungicides, daily dew removal increased the number of days needed to reach a 15-IC plot–1 point of reference when compared with fungicide treatments in which dew was not removed. The number of days required to reach 15 IC varied with fungicide, mowing frequency, and year the test was conducted. Results demonstrate that dollar spot control with fungicides can be extended when daily dew removal is employed and, in some cases, when mowing frequency is increased on dew-covered turf. Benefits of dew-removal practices on dollar spot and fungicide performance can vary with weather conditions, fungicide, threshold level, and possibly other factors.
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Jo, Young-Ki, Seog Won Chang, Michael Boehm, and Geunhwa Jung. "Rapid Development of Fungicide Resistance by Sclerotinia homoeocarpa on Turfgrass." Phytopathology® 98, no. 12 (December 2008): 1297–304. http://dx.doi.org/10.1094/phyto-98-12-1297.
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Dollar spot, caused by Sclerotinia homoeocarpa, is the most prevalent and economically important turfgrass disease in North America. Increasing levels of fungicide resistance, coupled with tightening environmental scrutiny of existing fungicides, has left fewer options for managing dollar spot. More knowledge about S. homoeocarpa populations is needed to improve dollar spot management strategies, especially with respect to minimizing the development of fungicide resistance. Population diversity of S. homoeocarpa was examined using inter-simple sequence repeat markers and vegetative compatibility assays. Two subgroups were found in S. homoeocarpa field populations on both fairway and putting green turfgrass at a research field in Wisconsin. These subgroups were genetically different, vegetatively incompatible, and had different fungicide sensitivities. The frequency of the two genetic subgroups differed significantly between the fairway and putting green, but was uniform within the fairway or within the green. Population dynamics of S. homoeocarpa in response to two systemic fungicides (thiophanate-methyl and propiconazole) were assessed based on in vitro fungicide sensitivity. Dynamics of S. homoeocarpa populations depended on the presence of fungicide-resistant isolates in the initial populations before fungicide applications and changed rapidly after fungicide applications. Shifting of the population toward propiconazole resistance was gradual, whereas thiophanate-methyl resistance developed rapidly in the population. In conclusion, field populations of S. homoeocarpa containing genetically distinct, vegetatively incompatible groups were different on turfgrass that was managed differently, and they were changed rapidly after exposure to fungicides.
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Ajayi-Oyetunde, Olutoyosi O., Carolyn J. Butts-Wilmsmeyer, and Carl A. Bradley. "Sensitivity ofRhizoctonia solanito Succinate Dehydrogenase Inhibitor and Demethylation Inhibitor Fungicides." Plant Disease 101, no. 3 (March 2017): 487–95. http://dx.doi.org/10.1094/pdis-07-16-1015-re.
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Soybean seedling diseases are caused by Rhizoctonia solani and can be managed with seed-applied fungicides that belong to different chemistry classes. To provide a benchmark for assessing a decline in sensitivities to these fungicide classes, R. solani isolates collected prior to 2001 were evaluated for their sensitivities to succinate dehydrogenase inhibitor (SDHI) (penflufen and sedaxane) and demethylation inhibitor (DMI) fungicides (ipconazole and prothioconazole). The effective concentration of each fungicide that reduced mycelial growth by 50% (EC50) was determined in vitro and compared with those of isolates recovered after 2011 from soybean plants with damping off and hypocotyl and root rot symptoms across different soybean-growing regions in the United States and Canada. All isolates, regardless of collection date, were extremely sensitive (EC50< 1 μg/ml) to the SDHI fungicides but were either extremely sensitive or moderately sensitive (1 ≤ EC50≤ 10 μg/ml) to the DMI fungicides. For all four active ingredients, variation in sensitivities was observed within and among the different anastomosis groups composing both isolate groups. Isolates collected after 2011, which also had varying in vitro sensitivities, were further evaluated for in vivo sensitivity to the four fungicides in the greenhouse. In vitro fungicide sensitivity did not always coincide with fungicide efficacy in vivo because all isolates tested, regardless of in vitro sensitivity, were effectively controlled by the application of the seed treatment fungicides in the greenhouse. Overall, our results indicate no shift in sensitivity to the fungicide classes evaluated, although considerable variability in the sensitivities of the two groups of isolates examined was present. Based on this research, continued monitoring of fungicide sensitivities of R. solani populations should occur to determine whether sensitivities become further reduced in the future.
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Koch, Paul L., Craig R. Grau, Young-Ki Jo, and Geunhwa Jung. "Thiophanate-Methyl and Propiconazole Sensitivity in Sclerotinia homoeocarpa Populations from Golf Courses in Wisconsin and Massachusetts." Plant Disease 93, no. 1 (January 2009): 100–105. http://dx.doi.org/10.1094/pdis-93-1-0100.
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Management of dollar spot, caused by the fungus Sclerotinia homoeocarpa, is dependent upon repeated fungicide applications in intensively managed turfgrass such as golf course putting greens and fairways. Repeated fungicide applications could potentially select for fungicide-resistant isolates and result in a reduction of disease control. The objectives of this study were to determine the degree of S. homoeocarpa in vitro sensitivity to the fungicides thiophanate-methyl and propiconazole using isolates collected from golf course putting greens, fairways, and roughs; and to determine the relationships of golf course age and fungicide history to the frequency of fungicide-insensitive isolates within the population. More than 1,400 S. homoeocarpa isolates were collected from putting greens, fairways, and roughs at six Wisconsin golf courses and one Massachusetts golf course and subjected to in vitro fungicide sensitivity assays with single discriminatory concentrations of thiophanate-methyl and propiconazole. Five of seven pathogen populations from rough areas were not significantly different from one another in propiconazole sensitivity. These populations were collectively the most sensitive to both fungicides and therefore, served as baseline populations for comparison with fungicide-exposed populations from putting greens and fairways. Greater propiconazole insensitivity was observed in populations collected from fairways and putting greens that received more frequent applications of the fungicide than those isolated from the roughs. In nearly all the golf courses, the frequency of thiophanate-methyl insensitivity was higher among isolates of S. homoeocarpa collected from fairways than from roughs regardless of the age of the golf course or history of benzimidazole use. Thus, while the development of resistance to propiconazole can be predicted in part by the relative frequency of demethylation inhibitor fungicide applications, the occurrence of populations resistant to thiophanate-methyl appears to be unrelated to recent use of the benzimidazole class of fungicides.
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Ju, Hyeon-Yeong, Mi-Ra Son, and Jin-Won Kim. "Response to Fungicides of Colletotrichum spp. Isolated from Red Peppers in Sunchang, Korea." Research in Plant Disease 27, no. 4 (December 31, 2021): 164–71. http://dx.doi.org/10.5423/rpd.2021.27.4.164.
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In August 2020, 377 anthracnose strains were isolated from anthracnose-infected peppers collected from 25 farms in Sunchang-gun, Jeollabuk-do. Inhibition rate of mycelial growth of 11 pepper anthracnose fungicides registered in Korea was investigated for 62 strains selected by region and the degree of susceptibility to each fungicide was investigated. As a result of the fungicide susceptibility test of anthracnose to the fungicide, no resistant strains were observed in fluazinam, prochloraz manganese, and benomyl, but resistant strains appeared in at least three areas for other fungicides, and all strains in all regions were resistant to dithianon. Through this, it was confirmed that the fungicide resistance was expressed in the strain group due to the continuous treatment of the fungicide in some areas. By region, resistant strains to seven pesticides appeared in Sunchang-eup and Paldeok-myeon, and resistant strains to six pesticides appeared in Geumgwa-myeon, Bokheung-myeon, Ssangchi-myeon, Yudeung-myeon, and Pungsan-myeon. There was no significant correlation between fungicide registration time and emergence of resistant strains.
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Jana, Poslušná, Plachká Eva, and Mazáková Jana. "Influence of selected fungicides registered in the Czech Republic for winter oilseed rape on in vitro Sclerotinia sclerotiorum mycelial growth." Plant Protection Science 54, No. 2 (February 10, 2018): 101–10. http://dx.doi.org/10.17221/137/2016-pps.
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The baseline sensitivity of 55 isolates of Sclerotinia sclerotiorum, collected from oilseed rape in 6 regions of the Czech Republic, to selected fungicides was determined during the period 2013–2015. One single-component fungicide – Horizon (tebuconazole), and four multicomponent fungicides – Pictor (boscalid, dimoxystrobin), Efilor (boscalid, metconazole), Prosaro 250 EC (prothioconazole, tebuconazole), and Propulse (fluopyram, prothioconazole), were chosen as these are commonly used locally. The effect of each fungicide on the in vitro pathogen radial mycelial growth and EC<sub>50 </sub>values for the respective fungicides were determined. The following MIC values were estimated; for the fungicides Horizon 250 EW, Efilor, and Propulse the mean MIC values ranged between 0.125 and 0.250 µl/ml, for Prosaro 250 EC ranged between 0.0625 and 0.125 µl/ml, and for Pictor ranged from 0.00781 to 0.01562 µl/ml. No strains of S. sclerotiorum resistant to the tested fungicides were detected and the growth of all isolates was fully inhibited at concentrations corresponding to their registered dose rates. The highest fungicidal efficacy on the collected S. sclerotiorum isolates was recorded for Pictor, followed by Prosaro 250 with an EC<sub>50</sub> value 0.05856 µl/ml and then the remaining fungicides Propulse, Efilor, and Horizon 250 EW (EC<sub>50</sub> values 0.07277, 0.07221, and 0.08519 µl/ml, respectively).
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PIMOHOVA, Lyudmila, German YaGOVENKO, and Zhanna TSARAPNEVA. "WHITE LUPIN PROTECTION AGAINST DISEASE’S COMPLEX." Adaptive Fodder Production 2020, no. 2 (August 14, 2020): 33–40. http://dx.doi.org/10.33814/afp-2222-5366-2020-2-33-40.
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Diseases are the main factor to decrease white lupin seed yield. Epiphytotic development of Fusarium occurs at lupin bud formation and flowering stagesunder soil drought conditions. Grey and white mold infect pods at high rain level in the second half of vegetation. The fungi disease anthracnose is the most harmful for lupin crops. Actual fungicides are necessary to protect white lupin crops; they have to be as well protective as to have cure action against disease’s complex without negative action for plants. The fungicide Vento (cresoxim-methyl 125 g/l + tebuconasol 140 g/l + epoxiconasol 116 g/l) at dose 1.0 l/ha has high effectiveness against anthracnose agent under laboratory and field conditions. The effectiveness of this dose against the disease was 94.1% under field conditions. At favorable conditions for disease development two treatments with the fungicide Vento decreases disease spreading and harmfulness for white lupin crops. At high level this fungicide protects white lupin plants against Fusarium and its pods against white and grey moldwhich significantly decreases seed yield losses. Thanks to the fungicide Vento saved yield made 1.95 t/ha during the experimental years. Costs’ payback for the fungicide’s use was 4.43 rubles per each invested one.
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Pereira, Danilo, Bruce A. McDonald, and Daniel Croll. "The Genetic Architecture of Emerging Fungicide Resistance in Populations of a Global Wheat Pathogen." Genome Biology and Evolution 12, no. 12 (September 28, 2020): 2231–44. http://dx.doi.org/10.1093/gbe/evaa203.
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Abstract Containing fungal diseases often depends on the application of fungicidal compounds. Fungicides can rapidly lose effectiveness due to the rise of resistant individuals in populations. However, the lack of knowledge about resistance mutations beyond known target genes challenges investigations into pathways to resistance. We used whole-genome sequencing data and association mapping to reveal the multilocus genetic architecture of fungicide resistance in a global panel of 159 isolates of Parastagonospora nodorum, an important fungal pathogen of wheat. We found significant differences in azole resistance among global field populations. The populations evolved distinctive combinations of resistance alleles which can interact when co-occurring in the same genetic background. We identified 34 significantly associated single nucleotide polymorphisms located in close proximity to genes associated with fungicide resistance in other fungi, including a major facilitator superfamily transporter. Using fungal colony growth rates and melanin production at different temperatures as fitness proxies, we found no evidence that resistance was constrained by genetic trade-offs. Our study demonstrates how genome-wide association studies of a global collection of pathogen strains can recapitulate the emergence of fungicide resistance. The distinct complement of resistance mutations found among populations illustrates how the evolutionary trajectory of fungicide adaptation can be complex and challenging to predict.
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Moyer, Michelle M., Jensena M. Newhouse, and Gary G. Grove. "Efficacy of Biopesticides and Leaf Removal in Grapevine Powdery Mildew Management." Plant Health Progress 17, no. 2 (January 2016): 84–91. http://dx.doi.org/10.1094/php-rs-16-0009.
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Integrating biological-based fungicides into conventional spray programs may help with fungicide resistance management. However, little is known about how to best integrate these products while still maintaining maximum disease control. Programs with as few as one synthetic fungicide or as many as three synthetic fungicides added to a biopesticide-based rotation during the bloom period of Vitis vinifera had significantly better disease control than a biopesticide-only-based program. When integrated with different timings of fruit-zone leaf removal, specific combinations of biopesticide programs and fruit-zone leaf removal enhanced the efficacy of that program to be on par with disease control seen in a program entirely based on synthetic fungicides. This suggests that when designing a fungicide program using biopesticides as a base, the addition of a synthetic fungicide during the window of ontogenic susceptibility in clusters and the adoption of cultural practices such as leaf removal can significantly improve the efficacy of that program. Accepted for publication 11 April 2016. Published 20 April 2016.
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Mikaberidze, Alexey, Bruce A. McDonald, and Sebastian Bonhoeffer. "Can High-Risk Fungicides be Used in Mixtures Without Selecting for Fungicide Resistance?" Phytopathology® 104, no. 4 (April 2014): 324–31. http://dx.doi.org/10.1094/phyto-07-13-0204-r.
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Fungicide mixtures produced by the agrochemical industry often contain low-risk fungicides, to which fungal pathogens are fully sensitive, together with high-risk fungicides known to be prone to fungicide resistance. Can these mixtures provide adequate disease control while minimizing the risk for the development of resistance? We present a population dynamics model to address this question. We found that the fitness cost of resistance is a crucial parameter to determine the outcome of competition between the sensitive and resistant pathogen strains and to assess the usefulness of a mixture. If fitness costs are absent, then the use of the high-risk fungicide in a mixture selects for resistance and the fungicide eventually becomes nonfunctional. If there is a cost of resistance, then an optimal ratio of fungicides in the mixture can be found, at which selection for resistance is expected to vanish and the level of disease control can be optimized.