Journal articles on the topic 'Root rot pathogens'
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1
El-Kazzaz, M. K., M. M. Badr, H. M. El-Zahaby, and M. I. Gouda. "Biological control of seedling damping-off and root rot of sugar beet plants." Plant Protection Science 38, SI 2 - 6th Conf EFPP 2002 (December 31, 2017): 645–47. http://dx.doi.org/10.17221/10580-pps.
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Some fungal and bacterial bioagents as well as an Actinomycete isolate were screened for their antagonistic effects against S. rolfsii, R. solani, M. phaseolina, F. oxysporum and F. solani in vitro. Trichoderma hamatum, T. harzianum, T. pseudokningii, certain isolates of Bacillus subtilis and one isolate of Pseudomonas fluorescens were the most effective bioagents in suppressing the radial growth of the four pathogens, in general. Yet, they were less effective in retarding growth of Fusarium spp. as compared with the other pathogens under study. Studying biological control showed the possibility of controlling sugar beet damping-off and root rot by certain bioagents as T. hamatum, T. hazianum, Pseudomonas fluorescens and B. subtilis under greenhouse (S. rolfsii-infested soil) and field (natural infection) conditions. These treatments also caused and increase root yield per plot.
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Hanson, L. E. "Interaction of Rhizoctonia solani and Rhizopus stolonifer Causing Root Rot of Sugar Beet." Plant Disease 94, no. 5 (May 2010): 504–9. http://dx.doi.org/10.1094/pdis-94-5-0504.
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In recent years, growers in Michigan and other sugar beet (Beta vulgaris) production areas of the United States have reported increasing incidence of root rot with little or no crown or foliar symptoms in sugar beet with Rhizoctonia crown and root rot. In addition, Rhizoctonia-resistant beets have been reported with higher levels of disease than expected. In examining beets with Rhizoctonia root rot in Michigan, over 50% of sampled roots had a second potential root rot pathogen, Rhizopus stolonifer. Growing conditions generally were not conducive to disease production by this pathogen alone, so we investigated the potential for interaction between these two pathogens. In greenhouse tests, four of five sugar beet varieties had more severe root rot symptoms when inoculated with both pathogens than when inoculated with either pathogen alone. This synergism occurred under conditions that were not conducive to disease production by R. stolonifer. Host resistance to Rhizoctonia crown and root rot reduced diseases severity, but was insufficient to control the disease when both pathogens were present. This raises concerns about correct disease diagnosis and management practices and indicates that a root rot complex may be important on sugar beet in Michigan.
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Al-Ani, R. A., M. A. Adhab, M. H. Mahdi, and H. M. Abood. "Rhizobium japonicum as a biocontrol agent of soybean root rot disease caused by Fusarium solani and Macrophomina phaseolina." Plant Protection Science 48, No. 4 (November 6, 2012): 149–55. http://dx.doi.org/10.17221/16/2012-pps.
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The activity of Rhizobium japonicum against the soil-borne pathogens Fusarium solani and Macrophomina phaseolina as causative agents of soybean root rot disease in both culture medium and soil was evaluated. Rhizobial culture filtrate caused an inhibition of the fungal radial growth of Fusarium solani and Macrophomina phaseolina on potato dextrose agar medium amended with the filtrate compared with control. The addition of rhizobial culture suspension to the soil contaminated by the two pathogens, Fusarium solani and Macrophomina phaseolina and their interaction, in pots, improved seed germination percentages and reduced the root rot disease index significantly. The sowing of rhizobial coated seeds in soil contaminated by Fusarium solani and Macrophomina phaseolina separately and in combination, in the field, increased seed germination significantly and induced a high reduction in disease severity for the same previous combination under field conditions. These results indicate that rhizobia could be an important element in root rot disease management.
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Kim, Dohyun, Taiying Li, Jungkwan Lee, and Seung-Ho Lee. "Biological Efficacy of Endophytic Bacillus velezensis CH-15 from Ginseng against Ginseng Root Rot Pathogens." Research in Plant Disease 28, no. 1 (March 31, 2022): 19–25. http://dx.doi.org/10.5423/rpd.2022.28.1.19.
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Ginseng is an important medicinal plant cultivated in East Asia for thousands of years. It is typically cultivated in the same field for 4 to 6 years and is exposed to a variety of pathogens. Among them, ginseng root rot is the main reason that leads to the most severe losses. In this study, endophytic bacteria were isolated from healthy ginseng, and endophytes with antagonistic effect against ginseng root rot pathogens were screened out. Among the 17 strains, three carried antagonistic effect, and were resistant to radicicol that is a mycotoxin produced by ginseng root rot pathogens. Finally, Bacillus velezensis CH-15 was selected due to excellent antagonistic effect and radicicol resistance. When CH-15 was inoculated on ginseng root, it not only inhibited the mycelial growth of the pathogen, but also inhibited the progression of disease. CH-15 also carried biosynthetic genes for bacillomycin D, iturin A, bacilysin, and surfactin. In addition, CH-15 culture filtrate significantly inhibited the growth and conidial germination of pathogens. This study shows that endophytic bacterium CH-15 had antagonistic effect on ginseng root rot pathogens and inhibited the progression of ginseng root rot. We expected that this strain can be a microbial agent to suppress ginseng root rot.
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Golosna, L., O. Afanasieva, G. Lisova, and L. Kucherova. "Isolation of sources of resistance of winter wheat samples to the group of pathogens as a component of immunological protection of plants." Interdepartmental Thematic Scientific Collection of Plant Protection and Quarantine, no. 63 (November 20, 2017): 42–50. http://dx.doi.org/10.36495/1606-9773.2017.63.42-50.
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In 2014—2016 on the artificial infectious background of the pathogens of Septoria leaf blotch, leaf rust and bunt, and on the natural background of powdery mildew and root rot, the stability of the collection of cultivars of winter wheat of different ecological and geographical origin was assessed. Perspective sources of group resistance to pathogens are identified to powdery mildew and root rot — Midas (Austria); to pathogens of powdery mildew and bunt — Radiance (Ukraine), Miranda (Romania), F94578G3-1/Bucur // Delabrad (Romania); to leaf rust and root rot — Mukhran (Germany) and Mv17/Zrn (Iran). To the pathogen Septoria leaf bloth of winter wheat resistant varieties is not detected.
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Šišić, Adnan, Jelena Baćanović-Šišić, Fernanda M. Gamba, and Maria R. Finckh. "Didymella pinodella: An Important Pea Root Rot Pathogen in France to Watch Out For?" Journal of Fungi 10, no. 1 (January 5, 2024): 44. http://dx.doi.org/10.3390/jof10010044.
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Root rot pathogens restrict pea and wheat production globally. In the EU, pea and pea-based cereal mixtures are being promoted; however, root rot pathogen dynamics in such mixtures are poorly understood. Winter pea and wheat were grown either in pure stands or in mixtures in the field in western France, and the severity of root rot in pea, wheat, and their mixtures, as well as the key pathogens associated with these crops, were assessed. Disease severity was moderate in pea and low in wheat, with no effect of sowing pattern. Didymella pinodella, a previously unreported pathogen in the pea–root rot complex in France, emerged as the most dominant pathogen in pea. It also occurred in low frequencies in wheat. Subsequent greenhouse aggressiveness tests showed that ten of the commonly grown pea cultivars in France lack resistance to D. pinodella. Among the Fusarium spp. isolated, F. avenaceum was the most frequent, occurring at similar frequencies in pea and wheat. In conclusion, D. pinodella may be an important pea root rot pathogen in France and there is a lack of resistance in the tested pea cultivars. In addition, F. avenaceum is a shared pathogen of wheat and pea.
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Weiland, Jerry E., Carolyn F. Scagel, Niklaus J. Grünwald, E. Anne Davis, Bryan R. Beck, and Val J. Fieland. "Variation in Disease Severity Caused by Phytophthora cinnamomi, P. plurivora, and Pythium cryptoirregulare on Two Rhododendron Cultivars." Plant Disease 102, no. 12 (December 2018): 2560–70. http://dx.doi.org/10.1094/pdis-04-18-0666-re.
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Rhododendrons are an important crop in the ornamental nursery industry, but are prone to Phytophthora root rot. Phytophthora root rot is a continuing issue on rhododendrons despite decades of research. Several Phytophthora species are known to cause root rot, but most research has focused on P. cinnamomi, and comparative information on pathogenicity is limited for other commonly encountered oomycetes, including Phytophthora plurivora and Pythium cryptoirregulare. In this study, three isolates each of P. cinnamomi, P. plurivora, and Py. cryptoirregulare were used to inoculate rhododendron cultivars Cunningham’s White and Yaku Princess at two different inoculum levels. All three species caused disease, especially at the higher inoculum level. P. cinnamomi and P. plurivora were the most aggressive pathogens, causing severe root rot, whereas Py. cryptoirregulare was a weak pathogen that only caused mild disease. Within each pathogen species, isolate had no influence on disease. Both P. cinnamomi and P. plurivora caused more severe disease on Cunningham’s White than on Yaku Princess, suggesting that the relative resistance and susceptibility among rhododendron cultivars might be similar for both pathogens. Reisolation of P. cinnamomi and P. plurivora was also greater from plants exhibiting aboveground symptoms of wilting and plant death and belowground symptoms of root rot than from those without symptoms. Results show that both P. cinnamomi and P. plurivora, but not Py. cryptoirregulare, are important pathogens causing severe root rot in rhododendron. This study establishes the risks for disease resulting from low and high levels of inoculum for each pathogen. Further research is needed to evaluate longer term risks associated with low inoculum levels on rhododendron health and to explore whether differences among pathogen species affect disease control.
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Msikita, W., B. Bissang, B. D. James, H. Baimey, H. T. Wilkinson, M. Ahounou, and R. Fagbemissi. "Prevalence and Severity of Nattrassia mangiferae Root and Stem Rot Pathogen of Cassava in Bénin." Plant Disease 89, no. 1 (January 2005): 12–16. http://dx.doi.org/10.1094/pd-89-0012.
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Root rot pathogens were found through diagnostic surveys in all departments (regions) of Bénin, West Africa, to affect 86 to 100% and 96 to 100% of cassava fields during the dry and rainy seasons, respectively. Disease incidence in individual fields ranged between 0 and 53%, and averaged 16 to 27% per department. Nattrassia mangiferae was consistently the most frequently isolated root rot pathogen (56% in the dry season and 22 to 52% in the rainy season). Pathogenicity of N. mangiferae was confirmed on four cultivars of cassava using stem cuttings and storage roots. For all four cultivars, N. mangiferae significantly reduced the number of roots. Lesions (3 to 15 cm long) formed on the lower stem portion of all inoculated plants, whereas control plants remained symptom free. On storage roots, the disease profile was similar to that formed on stem cuttings. Other root rot pathogens detected during the dry season were Macrophomina phaseolina (14.2%), Fusarium spp. (11.8%), Botryodiplodia theobromae (7.7%), and Pythium spp. (2.9%). During the rainy season, Fusarium spp. were the second most commonly isolated root rot pathogens in three departments (Atlantique, Borgou, and Mono). In Oueme and Zou, B. theobromae was the second most isolated root rot pathogen (ranging between 24 and 28%) during the rainy season. During the same season, Pythium spp. were pronounced in Borgou (18%), followed by Mono (11%), Atlantique (9%), Atacora (8%), Oueme (5%), and Zou (6%). Results of the study are discussed with a view to creating awareness of the destructive power of N. mangiferae, a hitherto poorly recognized root rot pathogen of cassava in Bénin and West Africa in general.
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Gossen, Bruce D., Robert L. Conner, Kan-Fa Chang, Julie S. Pasche, Debra L. McLaren, Maria A. Henriquez, Syama Chatterton, and Sheau-Fang Hwang. "Identifying and Managing Root Rot of Pulses on the Northern Great Plains." Plant Disease 100, no. 10 (October 2016): 1965–78. http://dx.doi.org/10.1094/pdis-02-16-0184-fe.
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Pulse crops (annual grain legumes such as field pea, lentil, dry bean, and chickpea) have become an important component of the cropping system in the northern Great Plains of North America over the last three decades. In many areas, the intensity of damping-off, seedling blight, root rot, and premature ripening of pulse crops is increasing, resulting in reduction in stand establishment and yield. This review provides a brief description of the important pathogens that make up the root rot complex and summarizes root rot management on pulses in the region. Initially, several specific Fusarium spp., a range of Pythium spp., and Rhizoctonia solani were identified as important components of the root rot disease complex. Molecular approaches have recently been used to identify the importance of Aphanomyces euteiches on pulses, and to demonstrate that year-to-year changes in precipitation and temperature have an important effect on pathogen prevalence. Progress has been made on management of root rot, but more IPM tools are required to provide effective disease management. Seed-treatment fungicides can reduce damping-off and seedling blight for many of the pathogens in this disease complex, but complex cocktails of active ingredients are required to protect seedlings from the pathogen complex present in most commercial fields. Partial resistance against many of the pathogens in the complex has been identified, but is not yet available in commercial cultivars. Cultural practices, especially diversified cropping rotations and early, shallow seeding, have been shown to have an important role in root rot management. Biocontrol agents may also have potential over the long term. Improved methods being developed to identify and quantify the pathogen inoculum in individual fields may help producers avoid high-risk fields and select IPM packages that enhance yield stability.
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Percival, G. C. "Influence of Pure Mulches on Suppressing Phytophthora Root Rot Pathogens." Journal of Environmental Horticulture 31, no. 4 (December 1, 2013): 221–26. http://dx.doi.org/10.24266/0738-2898.31.4.221.
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Mulching as a means of controlling Phytophthora root rot pathogens has become recognised as a potential cultural management system within the arboricultural, nursery and landscape industry. The influence of a pure mulch, i.e., mulch derived solely from one tree species, on reducing Phytophthora root rot severity has received little study. The purpose of the conducted research was to determine if a range of pure mulches derived from European beech (Fagus sylvatica L.), common hawthorn (Crataegus monogyna JACQ), silver birch (Betula pendula ROTH.), common cherry (Prunus avium L.), evergreen oak (Quercus ilex L.) and English oak (Q. robur L.) could reduce the development and impact of pathogen severity caused by Phytophthora cactorum and P. criticola on containerised horse chestnut (Aesculus hippocastanum). Irrespective of Phytophthora pathogen, leaf area, leaf, shoot, root and total plant dry weight following application of a pure mulch was higher than non-mulched controls. Likewise, leaf chlorophyll content, chlorophyll fluorescence Fv/Fm ratios, photosynthetic rates and root carbohydrate concentration as measures of tree vitality were higher in pure mulched compared to non-mulched control trees. Application of a pure mulch had a significant influence on Phytophthora root rot lesion severity. In the case of P. cactorum root rot lesion severity was reduced by 39–63%. In the case of P. criticola root rot lesion severity was reduced by 33–61%. In conclusion, pure mulches offer positive benefits for those involved in the care and maintenance of urban trees as well as nursery, forestry, orchard and horticultural crop production where Phytophthora pathogens are problematic.
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Wang, Chengxian, Jianfeng Liu, Changmei Wang, Xingling Zhao, Kai Wu, Bin Yang, Fang Yin, and Wudi Zhang. "Biogas slurry application alters soil properties, reshapes the soil microbial community, and alleviates root rot of Panax notoginseng." PeerJ 10 (July 26, 2022): e13770. http://dx.doi.org/10.7717/peerj.13770.
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Background Panax notoginseng is an important herbal medicine in China, where this crop is cultivated by replanting of seedlings. Root rot disease threatens the sustainability of P. notoginseng cultivation. Water flooding (WF) is widely used to control numerous soilborne diseases, and biogas slurry shows positive effects on the soil physiochemical properties and microbial community structure and has the potential to suppress soilborne pathogens. Hence, biogas slurry flooding (BSF) may be an effective approach for alleviating root rot disease of P. notoginseng; however, the underlying mechanism needs to be elucidated. Methods In this study, we conducted a microcosm experiment to determine if BSF can reduce the abundance of pathogens in soil and, alleviate root rot of P. notoginseng. Microcosms, containing soil collected from a patch of P. notoginseng showing symptoms of root rot disease, were subjected to WF or BSF at two concentrations for two durations (15 and 30 days), after which the changes in their physicochemical properties were investigated. Culturable microorganisms and the root rot ratio were also estimated. We next compared changes in the microbial community structure of soils under BSF with changes in WF and untreated soils through high-throughput sequencing of bacterial 16S rRNA (16S) and fungal internal transcribed spacer (ITS) genes amplicon. Results WF treatment did not obviously change the soil microbiota. In contrast, BSF treatment significantly altered the physicochemical properties and reshaped the bacterial and fungal communities, reduced the relative abundance of potential fungal pathogens (Fusarium, Cylindrocarpon, Alternaria, and Phoma), and suppressed culturable fungi and Fusarium. The changes in the microbial community structure corresponded to decreased root rot ratios. The mechanisms of fungal pathogen suppression by BSF involved several factors, including inducing anaerobic/conductive conditions, altering the soil physicochemical properties, enriching the anaerobic and culturable bacteria, and increasing the phylogenetic relatedness of the bacterial community. Conclusions BSF application can reshape the soil microbial community, reduce the abundance of potential pathogens, and alleviate root rot in P. notoginseng. Thus, it is a promising practice for controlling root rot disease in P. notoginseng.
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Stephens, Cameron M., Travis W. Gannon, Marc A. Cubeta, Tim L. Sit, and James P. Kerns. "Characterization and Aggressiveness of Take-All Root Rot Pathogens Isolated from Symptomatic Bermudagrass Putting Greens." Phytopathology® 112, no. 4 (April 2022): 811–19. http://dx.doi.org/10.1094/phyto-05-21-0215-r.
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Take-all root rot is a disease of ultradwarf bermudagrass putting greens caused by Gaeumannomyces graminis (Gg), Gaeumannomyces sp. (Gx), Gaeumannomyces graminicola (Ggram), Candidacolonium cynodontis (Cc), and Magnaporthiopsis cynodontis (Mc). Many etiological and epidemiological components of this disease remain unknown. Improving pathogen identification and our understanding of the aggressiveness of these pathogens along with growth at different temperatures will advance our knowledge of disease development to optimize management strategies. Take-all root rot pathogens were isolated from symptomatic bermudagrass root and stolon pieces from 16 different golf courses. Isolates of Gg, Gx, Ggram, Cc, and Mc were used to inoculate ‘Champion’ bermudagrass in an in planta aggressiveness assay. Each pathogen was also evaluated at 10, 15, 20, 25, 30, and 35°C to determine growth temperature optima. Infected plant tissue was used to develop a real-time PCR high-resolution melt assay for pathogen detection. This assay was able to differentiate each pathogen directly from infected plant tissue using a single primer pair. In general, Ggram, Gg, and Gx were the most aggressive while Cc and Mc exhibited moderate aggressiveness. Pathogens were more aggressive when incubated at 30°C compared with 20°C. While they grew optimally between 24.4 and 27.8°C, pathogens exhibited limited growth at 35°C and no growth at 10°C. These data provide important information on this disease and its causal agents that may improve take-all root rot management.
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Drake, Chrislyn A., and James F. Hancock. "(369) Field and Greenhouse Evaluation of Strawberry Genotypes for Tolerance to Black Root Rot Pathogens." HortScience 40, no. 4 (July 2005): 1058B—1058. http://dx.doi.org/10.21273/hortsci.40.4.1058b.
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Black root rot is a widespread disease of strawberry (Fragaria×ananassa Duchnesne) that causes the death of feeder roots and the degradation of structural roots. The major causal organisms of black root rot include Rhizoctonia fragariae Husain and W.E. McKeen, Pythiumspp. and Pratylenchuspenetrans(Cobb) Filipjev and Schuurmans Stekhoven. The current method of control for black root rot is methyl-bromide fumigation; however, methyl bromide is scheduled to be phased out in 2005, and its effects are short-lived in matted-row systems. The objectives of the study were to measure levels of tolerance to black root rot in 20 strawberry genotypes and to determine which pathogens were present in the soil. The genotypes were planted in four blocks each of methyl-bromide fumigated and nonfumigated soil, and were evaluated for crown number, number of flowers per crown, yield, and average berry weight over two years. The results showed that all three pathogens were present in the field, and that there was a significant genotype × fumigation interaction for yield and crown number in both years. The cultivars Bounty, Cabot, and Cavendish, all released from the breeding program in Nova Scotia, displayed tolerance to the pathogens that cause BRR. Greenhouse studies were conducted using a subset of the genotypes to determine if any one pathogen causes more damage than others, and to determine if susceptibility to a particular pathogen varies between genotypes.
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Sabet, Kamel Kamal, Magdy Mohamed Saber, Mohamed Adel-Aziz El-Naggar, Nehal Samy El-Mougy, Hatem Mohamed El-Deeb, and Ibrahim El-Saied El-Shahawy. "Using Commercial Compost as Control Measures against Cucumber Root-Rot Disease." Journal of Mycology 2013 (May 15, 2013): 1–13. http://dx.doi.org/10.1155/2013/324570.
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Five commercial composts were evaluated to suppress the root-rot pathogens (Fusarium solani (Mart.) App. and Wr, Pythium ultimum Trow, Rhizoctonia solani Kuhn, and Sclerotium rolfsii Sacc.) of cucumber plants under in vitro and greenhouse conditions. In vitro tests showed that all tested unautoclaved and unfiltrated composts water extracts (CWEs) had inhibitor effect against pathogenic fungi, compared to autoclaved and filtrated ones. Also, the inhibitor effects of 40 bacteria and 15 fungi isolated from composts were tested against the mycelial growth of cucumber root-rot pathogens. Twenty two bacteria and twelve fungal isolates had antagonistic effect against root-rot pathogens. The antagonistic fungal isolates were identified as 6 isolates belong to the genus Aspergillus spp., 5 isolates belong to the genus Penicillium spp. and one isolate belong to the genus Chaetomium spp. Under greenhouse conditions, the obtained results in pot experiment using artificial infested soil with cucumber root-rot pathogens showed that the compost amended soil reduced the percentage of disease incidence, pathogenic fungi population, and improved the cucumber vegetative parameters as shoot length, root length, fresh weight, and dry weight. These results suggested that composts are consequently considered as control measure against cucumber root-rot pathogens.
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Saad, Ahmed, Bethany Macdonald, Anke Martin, Noel L. Knight, and Cassandra Percy. "Comparison of disease severity caused by four soil-borne pathogens in winter cereal seedlings." Crop and Pasture Science 72, no. 5 (2021): 325. http://dx.doi.org/10.1071/cp20245.
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In Australia, crown rot of cereals is predominantly caused by Fusarium pseudograminearum and Fusarium culmorum, and common root rot by Bipolaris sorokiniana. Fusarium graminearum is an important pathogen causing Fusarium head blight worldwide and has also been reported to cause crown rot of wheat. The comparative ability of F. pseudograminearum, F. culmorum, F. graminearum and B. sorokiniana to cause crown rot and common root rot across a range of winter cereal species requires investigation. In glasshouse trials, we inoculated one cultivar each of barley, bread wheat, durum wheat, oat and triticale with two strains of each of the four pathogens. At 21 days after inoculation, the sub-crown internode and leaf sheaths of each plant were visually rated for brown discoloration. Shoot length and dry weight of inoculated plants were compared with those of non-inoculated controls. Barley and bread wheat had the highest disease severity ratings on leaf sheaths and sub-crown internode (64.7–99.6%), whereas oat had the lowest disease severity ratings across all pathogens (<5%). The shoot length of all cultivars was significantly reduced (by 12.2–55%, P < 0.05) when exposed to F. pseudograminearum. This study provides a comparison of pathogenicity of crown rot and common root rot pathogens and demonstrates significant variation in visual discoloration and host response across a range of winter cereals.
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Biernacki, M., and B. D. Bruton. "Quantitative Response of Cucumis melo Inoculated with Root Rot Pathogens." Plant Disease 85, no. 1 (January 2001): 65–70. http://dx.doi.org/10.1094/pdis.2001.85.1.65.
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This experiment quantified the effects of three root rot pathogens on muskmelon (Cucumis melo L., var. cantalupensis) growth traits using computerized image analysis. Plants were grown from seed in sand infested with the soilborne pathogen Monosporascus cannonballus, Acremonium cucurbitacearum, or Rhizopycnis vagum. After 28 days in the growth chamber, images of plants were analyzed to quantify their response. Compared to noninoculated muskmelons, inoculated plants had significantly increased mean root diameter (45%), decreased root length (26%, primarily in roots of <0.5 mm diameter), decreased number of root tips (27%), decreased rhizosphere volume (40%), and decreased cumulative and mean surface area of leaves (24%). Effects of M. cannonballus on muskmelon growth were significantly different compared to A. cucurbitacearum and R. vagum. Isolate effects manifested a greater magnitude of difference on muskmelon traits than those observed at the species level. Multivariate analyses of plant responses were more powerful than univariate analyses to differentiate among effects of pathogen species and pathogen isolates. Discriminant analysis were useful to identify groups of plant traits modified by each fungal species or isolate at low disease levels. Digital image analyses proved to be a useful technique in quantitative assessment of plant damage caused by soilborne root rot pathogens.
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Traquair, James A. "Fungal biocontrol of root diseases: endomycorrhizal suppression of cylindrocarpon root rot." Canadian Journal of Botany 73, S1 (December 31, 1995): 89–95. http://dx.doi.org/10.1139/b95-230.
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Many reviews in the past decade outline the need to understand the complex interactions between fungal pathogens of roots, mycorrhizal fungi, mycorrhizosphere associates, and various climatic and edaphic factors to develop stable mycorrhizal biocontrol strategies. Cylindrocarpon root rot caused by Cylindrocarpon destructans is a good example of a replant disorder that is amenable to this type of control in nurseries and new or renovated orchard sites. Cylindrocarpon root rot was reduced by endomycorrhizal colonization of potted peach rootstocks with Glomus aggregatum under controlled environment conditions using Turface or natural, untreated orchard soils. Several mechanisms of suppression are discussed including tolerance to the pathogen through increased host vigor and reduced exudation, competition for space and nutrients, and induced host resistance. Technical innovations and new concepts of fungal community ecology are improving the odds of developing effective biocontrols with mycorrhizae. Exploitation of natural and integrated disease management using multiple mechanisms of pathogen inhibition may offset the difficulties in inoculum preparation. Key words: Cylindrocarpon destructans, antagonism, competition, rhizosphere, mycorrhizosphere.
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Jacobsen, Barry. "Root rot diseases of sugar beet." Zbornik Matice srpske za prirodne nauke, no. 110 (2006): 9–19. http://dx.doi.org/10.2298/zmspn0610009j.
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Root rot diseases of sugar beet caused by Rhizoctonia solani (AG 2-2 IIIB and AG 2-2 IV), R. crocorum, Aphanomyces cochlioides, Phoma betae, Macrophomina phaeseolina, Fusarium oxysporum f.sp. radicis-betae, Pythium aphanidermatum Phytophthora drechsleri, Rhizopus stolonifer, R. arrhizus and Sclerotium rolfsii cause significant losses wherever sugar beets are grown. However, not all these soil-borne pathogens have been reported in all sugar beet production areas. Losses include reduced harvestable tonnage and reduced white sugar recovery. Many of these pathogens also cause post harvest losses in storage piles. Control for diseases caused by these pathogens include disease resistant cultivars, avoidance of stresses, cultural practices such as water management and the use of fungicides.
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Denisyuk, E. S. "Efficiency of the microbiological products based on Bacillus subtilis and Trichoderna harzianum in protection of spring barley from diseases in the North-West of Russia." Biotekhnologiya 36, no. 1 (2020): 61–72. http://dx.doi.org/10.21519/0234-2758-2020-36-1-61-72.
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The efficacy of microbiological plant protection specimens based on Bacillus subtilis (Vitapan, SP) and Trichoderna harzianum (Trikhotsin, SP) was studied on such spring barley diseases as a root rot and Helminthosporium leaf spot. The use of these biological products in the treatment of seeds and vegetative plants of spring barley was ineffective, namely a decrease in the development of root rot and helminthosprium disease did not exceed 35%. A greater protective effect was achieved when using studied preparations for treating seeds with a low degree of infection with the main pathogen of root rot. The use of Vitaplan in a tank mixture with reduced consumption rates of the chemical fungicides was less effective than pure chemicals with full consumption rates: the decrease was 17% for root rot and 12.7% for Helminthosporium leaf spot. Thus, it is advisable to use mixtures of chemicals with the Vitaplan as a biological for treatment of seeds with an average degree of infection by root rot pathogens and a predicted moderate development of Helminthosporium disease. spring barley, biological plantprotecting agents, root rot, protective efficiency.
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Chhetri, Vivek Thapa, Resham G.C., Sanup Chaudhary, Sachin Timilsina, and Subash Gautam. "Pests, pathogens, pathogenic diseases, and diseases control strategies of sal (Shorea robusta) in Nepal." Archives of Agriculture and Environmental Science 6, no. 2 (June 25, 2021): 210–17. http://dx.doi.org/10.26832/24566632.2021.0602013.
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Sal (Shorea robusta) is one of the most indispensable species in Nepal, both ecologically and economically. This paper aims to provide updated guidance for the management and protection of this species in the future from various pests and pathogens. We reviewed 38 articles from Google Scholar and Research gate with keywords "Shorea robusta”, “Hoplocerambyx spinicornis”, “Polyporus shoreae”, “Heart rot”. S. robusta has the most insect fauna among the forest tree species. Out of the 346 insects reported on S. robusta, around 155 species of insects are associated with living trees. Hoplocerambyx spinicornis is the most destructive insect pest, wreaking havoc on S. robusta. Polyporous shoreae is the main cause of root rot in S. robusta, and spreads through root contact or root grafting. Heart rot in S. robusta is caused by the fungi Hymenochaete rubiginosa, Fomes caryophylli, and F. fastuosus. During the harvesting of S. robusta, the majority of the tree was observed to be faulty, resulting in a large amount of waste wood. The best way to determine the pathogen's "Achilles' heel" is to consider its life cycle. The Nepalese famous saying "prevention is better than cure" may be applicable in the management of S. robusta insect pests and pathogens. The current paper critically addresses these issues and argues the need for an improvised package of activities for insect pests, pathogens, prevention, and their control.
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Bischoff Nunes, Isadora, and Paul H. Goodwin. "Interaction of Ginseng with Ilyonectria Root Rot Pathogens." Plants 11, no. 16 (August 19, 2022): 2152. http://dx.doi.org/10.3390/plants11162152.
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The Ilyonectria radicicola species complex (A.A. Hildebr.) A. Cabral and Crous 2011 contains species of soilborne necrotrophic plant pathogens. The most aggressive to ginseng roots is I. mors-panacis, whereas I. robusta, I. crassa, I. panacis and I. radicicola are less aggressive. Infected ginseng roots show orange-red to black-brown lesions that can expand into a severe root rot, known as disappearing root rot, where only epidermal root tissue remains. Leaves become red-brown with wilting, and stems can have vascular discoloration with black-brown lesions at the base. Less aggressive Ilyonectria species trigger jasmonic acid (JA)-related defenses inducing host ginsenosides, pathogenesis-related (PR) proteins, wound periderm, and cell wall thickening. In contrast, I. mors-panacis triggers reactive oxygen species (ROS) and salicylic acid (SA) production but suppresses JA-related defenses and ginsenoside accumulation. It is also able to suppress SA-related PR protein production. Virulence factors include potential effectors that may suppress PAMP (Pathogen Associated Molecular Patterns) triggered immunity (PTI), polyphenoloxidases, Hsp90 inhibitors, siderophores and cell-wall-degrading enzymes, such as pectinases. Overall, I. mors-panacis appears to be more aggressive because it can suppress JA and SA-related PTI allowing for more extensive colonization of ginseng roots. While many possible mechanisms of host resistance and pathogen virulence mechanisms have been examined, there is a need for using genetic approaches, such as RNAi silencing of genes of Panax or Ilyonectria, to determine their importance in the interaction.
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Astapchuk, Irina, Galina Yakuba, and Andrei Nasonov. "Pathocomplex of root rot of apple tree in nurseries and young orchards of the South of Russia." BIO Web of Conferences 25 (2020): 06002. http://dx.doi.org/10.1051/bioconf/20202506002.
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Root rot poses a serious threat to the main fruit crop domestic apple in nurseries and young orchards. Obtaining healthy planting material, free from root pathogens and root rot, is an especially priority task in conditions of intensive production. In the process of analyzing the affected plants from nurseries and young orchards at four sampling points, pathogens of apple root rot from 11 genera were identified and 431 isolates were extracted. The most common causative agents of apple root rot seedlings in the entire studied sample were species of the genus Fusarium spp. Soil micromycetes such as Rhizoctonia spp., Cladosporium spp., Cylinrocarpon spp., and oomycetes from the genus Pythium were rare. The composition and occurrence of species were heterogeneous at different points in the studied region. Phomopsis mali (Schulzer & Sacc.) Died., Cytospora spp., Alternaria alternate (Fr.) Keissl., and Aspergillus niger Tiegh. have been associated with root rot of seedlings and young apple trees.
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Hrytsiuk, N. "Resistance of winter wheat varieties to root rots causative agents against artificial infection." Interdepartmental Thematic Scientific Collection of Phytosanitary safety, no. 69 (March 14, 2024): 52–61. http://dx.doi.org/10.36495/1606-9773.2023.69.52-61.
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Goal. The study of the varieties of domestic and foreign selection of winter wheat for resistance to the main pathogens of root rot (Fusarium graminearum and Bipolaris sorokiniana) and the determination of their harmfulness.
Methods. Laboratory method — for the isolation of pathogens in pure culture, for artificial infection with pathogens of root rot, for the determination of growth parameters of winter wheat; dispersive, statistical and regressive methods for the reliability of the obtained results.
Results. The agressiveness and the virulence of the main causative agents of winter wheat root rot under artificial seed infection have been established. The assessment of the resistance of winter wheat varieties to Fusarium and Helminthosporium root rot was carried out, the development of the disease in relatively resistant varieties ranged from 0.1 to 0.9 points, the spread was 10.0—45.5%; the development of weak–resistant varieties was 1.0—1.2 points, prevalence of 40.9—50.0%; the developmen tof susceptible varieties was 1.7—2.23 points, spreading — 71.8—94.0%. The harmfulness of Fesarium graminearum and Bipolaris sorokiniana on seedling and root length was studied. In susceptible to Fusarium rot varieties of Novosmuglianka, Poliska 90, Lisova Pisnia, the seedling length was reduced by 5.7—6.9 cm, the root length was reduced by 2.51—3.21 cm compared to relatively resistant Samurai varieties.
Conclusions. The most common types of root rot in Zhytomyr region are Fusarium and Helminthosporous root rot. No root rot resistant varieties of winter wheat were found among the research varieties, but relatively resistant and weak-resistant varieties were selected. For sowing on agricultural enterprises, relatively resistant to Fusarium graminearum and Bipolaris sorokiniana varieties of Samurai, Kraievyd, Podolianka, Scagen can be recommended. Weak-resistant to Fusariosis can be recommended Bohemia, Podarunok Podillia varieties and weak-resistant to helminth sporiasis can be recommended Poliska 90. In protection of winter wheat crops from harmful organisms, the correct selection of varieties plays a special role, therefore, when developing the integrated protection technology, special attention should be paid to the varieties that show resistance to certain diseases and types of pathogens.
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Xue, Allen G. "Biological Control of Pathogens Causing Root Rot Complex in Field Pea Using Clonostachys rosea Strain ACM941." Phytopathology® 93, no. 3 (March 2003): 329–35. http://dx.doi.org/10.1094/phyto.2003.93.3.329.
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Pea root rot complex (PRRC), caused by Alternaria alternata, Aphanomyces euteiches, Fusarium oxysporum f. sp. pisi, F. solani f. sp. pisi, Mycosphaerella pinodes, Pythium spp., Rhizoctonia solani, and Sclerotinia sclerotiorum, is a major yield-limiting factor for field pea production in Canada. A strain of Clonostachys rosea (syn. Gliocladium roseum), ACM941 (ATCC 74447), was identified as a mycoparasite against these pathogens. When grown near the pathogen, ACM941 often was stimulated to produce lateral branches that grew directly toward the pathogen mycelium, typically entwining around the pathogen mycelium. When applied to the seed, ACM941 propagated in the rhizosphere and colonized the seed coat, hypocotyl, and roots as the plant developed and grew. ACM941 significantly reduced the recovery of all fungal pathogens from infected seed, increased in vitro seed germination by 44% and seedling emergence by 22%, and reduced root rot severity by 76%. The effects were similar to those of thiram fungicide, which increased germination and emergence by 33 and 29%, respectively, and reduced root rot severity by 65%. When soil was inoculated with selected PRRC pathogens in a controlled environment, seed treatment with ACM941 significantly increased emergence by 26, 38, 28, 13, and 21% for F. oxysporum f. sp. pisi, F. solani f. sp. pisi, M. pinodes, R. solani, and S. sclerotiorum, respectively. Under field conditions from 1995 to 1997, ACM941 increased emergence by 17, 23, 22, 13, and 18% and yield by 15, 6, 28, 6, and 19% for the five respective pathogens. The seed treatment effects of ACM941 on these PRRC pathogens were greater or statistically equivalent to those achieved with thiram. Results of this study suggest that ACM941 is an effective bioagent in controlling PRRC and is an alternative to existing chemical products.
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Persson, L., L. Bødker, and M. Larsson-Wikström. "Prevalence and Pathogenicity of Foot and Root Rot Pathogens of Pea in Southern Scandinavia." Plant Disease 81, no. 2 (February 1997): 171–74. http://dx.doi.org/10.1094/pdis.1997.81.2.171.
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The occurrence of root pathogens of vining pea was determined in field surveys in Sweden and Denmark from 1989 to 1994. The most serious yield-reducing root pathogen, Aphanomyces euteiches, was found in approximately one-third of the sampled fields in both Sweden and Denmark. In a few fields severely infested with this pathogen, there was a total crop failure. The most frequently isolated pathogens were Phoma medicaginis var. pinodella and Fusarium solani; the latter also was isolated from vascular tissue up to the seventh node level. Other pathogens isolated from roots were F. avenaceum, F. oxysporum, F. culmorum, Chalara elegans, Pythium irregulare, and Mycosphaerella pinodes. In greenhouse pathogenicity tests, A. euteiches caused the most severe root damage and plant death of pea, followed by F. avenaceum and P. irregulare. There was an inverse relationship between field disease severity index and yield for fields infested with A. euteiches.
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Weiland, Jerry E., Carolyn F. Scagel, Niklaus J. Grünwald, E. Anne Davis, Bryan R. Beck, Zachary S. L. Foster, and Valerie J. Fieland. "Soilborne Phytophthora and Pythium Diversity From Rhododendron in Propagation, Container, and Field Production Systems of the Pacific Northwest." Plant Disease 104, no. 6 (June 2020): 1841–50. http://dx.doi.org/10.1094/pdis-08-19-1672-re.
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Rhododendron root rot is a severe disease that causes significant mortality in rhododendrons. Information is needed about the incidence and identity of soilborne Phytophthora and Pythium species causing root rot in Pacific Northwest nurseries in order to better understand the disease etiology and to optimize disease control strategies. The last survey focusing solely on soilborne oomycete pathogens in rhododendron production was conducted in 1974. Since then, advances in pathogen identification have occurred, new species may have been introduced, pathogen communities may have shifted, and little is known about Pythium species affecting this crop. Therefore, a survey of root-infecting Phytophthora and Pythium species was conducted at seven nurseries from 2013 to 2017 to (i) document the incidence of root rot damage at each nursery and stage of production, (ii) identify soilborne oomycetes infecting rhododendron, and (iii) determine whether there are differences in pathogen diversity among nurseries and production systems. Rhododendrons from propagation, container, and field systems were sampled and Phytophthora and Pythium species were isolated from the roots and collar region. Root rot was rarely evident in propagation systems, which were dominated by Pythium species. However, severe root rot was much more common in container and field systems where the genus Phytophthora was also more prevalent, suggesting that Phytophthora species are the primary cause of severe root rot and that most contamination by these pathogens comes in after the propagation stage. In total, 20 Pythium species and 11 Phytophthora species were identified. Pythium cryptoirregulare, Pythium aff. macrosporum, Phytophthora plurivora, and Phytophthora cinnamomi were the most frequently isolated species and the results showed that Phytophthora plurivora has become much more common than in the past. Phytophthora diversity was also greater in field systems than in propagation or container systems. Risks for Phytophthora contamination were commonly observed during the survey and included placement of potting media in direct contact with field soil, the presence of dead plants that could serve as continuous sources of inoculum, and the presence of excess water as a result of poor drainage, overirrigation, or malfunctioning irrigation equipment. In the past, research on disease development and root rot disease control in rhododendron focused almost exclusively on Phytophthora cinnamomi. More research is needed on both of these topics for the other root-infecting species identified in this survey.
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Smitha H. S., Prashantha A., Sumangala Koulagi, Dileepkumar Masuthi, and Vijaykumar Dondiba Rathod. "Morphological, Molecular Identification and Pathogenicity of Rhizoctonia solani Kuhn: A Seed and Soil Borne Pathogen Infecting French Bean." International Journal of Environment and Climate Change 13, no. 12 (December 18, 2023): 309–16. http://dx.doi.org/10.9734/ijecc/2023/v13i123686.
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French bean (Phaseolus vulgaris L.), holds significant importance as a both vegetable and pulse crop in India. Root rot disease has become threat for successful french bean cultivation. Fusarium spp., Sclerotium rolfsii, Rhizoctonia sp., Macrophomina, Pythium spp. and Thielaviopsis sp. may incite root rot disease in french bean. The root rot caused by Rhizoctonia soalni Kuhn is one among the root rot causing pathogens, is a major devasticating disease in this crop. The objective of this investigation was to perform the morphological, molecular identification and pathogenicity of R. solani Kuhn infecting french bean root rot. The pathogen was isolated from the naturally infected french bean field with characteristic symptoms like yellowing, drying at the soil level, stunting, poor seedling establishment, uneven growth, chlorosis, and premature defoliation in severely affected cases. It was isolated using standard tissue isolation technique and identified based on morphological traits. The fungus was molecular identified by sequencing ITS region of rDNA by using ITS1 and ITS4 primers. Further, pathogenicity of R. solani was proved according to Koch’s postulates.
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Iqbal, Mudassir, Maha Jamshaid, Muhammad Awais Zahid, Erik Andreasson, Ramesh R. Vetukuri, and Johan A. Stenberg. "Biological control of strawberry crown rot, root rot and grey mould by the beneficial fungus Aureobasidium pullulans." BioControl 66, no. 4 (March 18, 2021): 535–45. http://dx.doi.org/10.1007/s10526-021-10083-w.
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AbstractUtilization of biocontrol agents is a sustainable approach to reduce plant diseases caused by fungal pathogens. In the present study, we tested the effect of the candidate biocontrol fungus Aureobasidium pullulans (De Bary) G. Armaud on strawberry under in vitro and in vivo conditions to control crown rot, root rot and grey mould caused by Phytophthora cactorum (Lebert and Cohn) and Botrytis cinerea Pers, respectively. A dual plate confrontation assay showed that mycelial growth of P. cactorum and B. cinerea was reduced by 33–48% when challenged by A. pullulans as compared with control treatments. Likewise, detached leaf and fruit assays showed that A. pullulans significantly reduced necrotic lesion size on leaves and disease severity on fruits caused by P. cactorum and B. cinerea. In addition, greenhouse experiments with whole plants revealed enhanced biocontrol efficacy against root rot and grey mould when treated with A. pullulans either in combination with the pathogen or pre-treated with A. pullulans followed by inoculation of the pathogens. Our results demonstrate that A. pullulans is an effective biocontrol agent to control strawberry diseases caused by fungal pathogens and can be an effective alternative to chemical-based fungicides.
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Sumbul, A., and I. Mahmood. "Interactive effect of Meloidogyne incognita and Macrophomina phaseolina on the development of root–rot disease complex in relation to growth and physiological attributes of chickpea." Hellenic Plant Protection Journal 13, no. 1 (January 1, 2020): 13–23. http://dx.doi.org/10.2478/hppj-2020-0002.
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SummaryThe interactive relationship between the root–knot nematode Meloidogyne incognita and the root-rot fungus Macrophomina phaseolina in a root–rot disease complex of chickpea (Cicer arietinum var. avrodhi) was studied in a net house. The present study was carried out in such a manner so that the pathogenic potential of M. incognita and M. phaseolina individually, simultaneously and sequentially could be monitored. The pathogens singly as well as in combination led to significant reduction in growth, yield, nutrient and biochemical parameters. Gaseous exchange parameters like photosynthetic rate, transpiration rate and stomatal conductance were also reduced following infection of plants by the pathogens. However, maximum reduction was noticed in simultaneous inoculation with both pathogens. Sequential inoculation, where M. incognita preceded M. phaseolina by 15 days, was more damaging to the crop in comparison to that where M. phaseolina preceded M. incognita inoculation by 15 days. Infection by M. phaseolina caused a considerable reduction in the number of galls, egg–masses and nematode multiplication, with the highest reduction observed in plants simultaneously inoculated with the pathogens. Those plants also showed the highest disease severity in terms of percent root–rot. Thus, a manifold action plan to reduce the impact of the root-rot disease complex on chickpea crops has to be formulated.
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Paul, Narayan Chandra, Soyoon Park, Haifeng Liu, Ju Gyeong Lee, Gui Hwan Han, Hyunsook Kim, and Hyunkyu Sang. "Fungi Associated with Postharvest Diseases of Sweet Potato Storage Roots and In Vitro Antagonistic Assay of Trichoderma harzianum against the Diseases." Journal of Fungi 7, no. 11 (October 31, 2021): 927. http://dx.doi.org/10.3390/jof7110927.
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Sweet potato is the 11th most important food crop in the world and an excellent source of nutrition. Postharvest diseases were monitored in sweet potato storage roots collected from the local markets in Korea during 2021. Several diseases including Fusarium surface and root rot, charcoal rot, dry rot, and soft rot were observed in the postharvest sweet potatoes. A total of 68 fungal isolates were obtained from the diseased samples, and the isolates were grouped into 8 different fungal colony types. Based on multilocus phylogeny and morphological analysis of 17 representative isolates, the isolates were identified as Fusarium oxysporum, F. ipomoeae, F. solani, Penicillium citrinum, P. rotoruae, Aspergillus wentii, Mucor variicolumellatus (Mu. circinelloides species complex), and Macrophomina phaseolina. F. oxysporum was the predominant pathogen as this is the most common pathogen of sweet potato storage roots causing the surface rot disease, and M. phaseolina caused the most severe disease among the pathogens. Dual culture antagonistic assays were evaluated using Trichoderma harzianum strains CMML20–26 and CMML20–27. The results revealed that the two strains showed strong antifungal activity in different ranges against all tested pathogens. This study provides an understanding of diverse postharvest diseases in sweet potatoes and suggests potential biocontrol agents to manage the diseases. In addition, this is the first report of sweet potato storage root rot diseases caused by A. wentii, and P. rotoruae worldwide.
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Conner, Robert L., Anfu Hou, Parthiba Balasubramanian, Debra L. McLaren, Maria A. Henriquez, Kan-Fa Chang, and Kenneth B. McRae. "Reaction of dry bean cultivars grown in western Canada to root rot inoculation." Canadian Journal of Plant Science 94, no. 7 (September 2014): 1219–30. http://dx.doi.org/10.4141/cjps2013-416.
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Conner, R. L., Hou, A., Balasubramanian, P., McLaren, D. L., Henriquez, M. A., Chang, K.-F. and McRae, K. B. 2014. Reaction of dry bean cultivars grown in western Canada to root rot inoculation. Can. J. Plant Sci. 94: 1219–1230. Root rot is an important disease of dry beans (Phaseolus vulgaris) that is caused by a complex of root pathogens. Cultural and fungicidal controls are available to reduce the adverse impact of this disease on seedling emergence, plant growth and yield, but none of these practices are highly effective. The development of disease-resistant dry bean cultivars is considered to be an important component of an integrated management system for root rot control. A 5-yr field study was conducted to identify potential sources of resistance to seedling blight and root rot in dry bean cultivars that are widely grown in western Canada. A total of 37 dry bean cultivars, representing all the bean classes grown in the region, were tested against the root rot pathogens Rhizoctonia solani, Fusarium solani, F. redolens and F. acuminatum. Partial root rot resistance was detected in the navy bean cultivar Navigator and the black bean cultivars Black Violet and CDC Jet. The greatest root rot resistance occurred in the cranberry bean cultivars Etna and Cran 09. Reductions in root rot severity were not consistently associated with greater seedling emergence, which indicates that resistance to seedling blight and root rot may be independent traits. Inoculation with R. solani had the most adverse effect on seedling emergence, while infection by F. solani f. sp. phaseoli resulted in the most severe root rot ratings.
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AVAN, Meltem, Gülsüm PALACIOĞLU, Tülin SARIGÜL ERTEK, Yakup Zekai KATIRCIOĞLU, Harun BAYRAKTAR, Rıza KAYA, and Salih MADEN. "Sugar beet root rot caused by oomycetous pathogens in Turkey and their control by seed treatmen." TURKISH JOURNAL OF AGRICULTURE AND FORESTRY 44, no. 6 (December 8, 2020): 631–41. http://dx.doi.org/10.3906/tar-1910-55.
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The aim of this study was to determine the oomycetous pathogens causing root rot on sugar beet and test their control by seed treatment in Konya Province, Turkey. Oomycetous fungus-like pathogens of sugar beet were investigated using 866 plant samples collected at 2 growth stages, early seedling and late root, from fields in the Konya region of Turkey and 1 sample from the Thrace region. Herein, 10 oomycetous species belonging to 3 genera: Aphanomyces cochlioides, Phytophthora cryptogea, Ph. pseudocryptogea, Ph. megasperma, Ph. inundata, Pythium aphanidermatum, Py. helicoides, Py. heterothallicum, Py. sylvaticum, and Py. ultimum var. ultimum (Globisporangium ultimum var. ultimum) were discovered at various times with in the 2 growth periods, all of which were the first records for Turkey. A. cochlioides was the most serious pathogen, both in terms of its wide distribution and aggressiveness. The pathogen produced more than 90% disease severity when tested by soil infestation at the seedling stage, although it also occurred at the late root growth stage. Pythium species were also ascommon, such as A. cochlioides, the majority of which were very aggressive, producing more than 84% disease severity at the seedling stage, except for Py. aphanidermatum. Half-strength potato dextrose agar medium was found to be very useful for the isolation of all of the pathogens from the plant samples at both stages. Morphological features of all of the pathogens were abundantly produced when the pathogens were grown on amended grated carrot agar medium and culture disks of fungal growth of this medium were submerged in sterile and nonsterile soil extracts. Out of the 15 fungicide mixes tested, 2 mixes, thiram+metalaxyl+hymexazole and thiram+metalaxyl+hymexazole+ pyraclostrobin reduced seedling root rot caused by both A. cochlioides and Pythium ultimum var. ultimum, while the standard seed treatment fungicide mix of thiram+hymexazole was not effective against either of the pathogens.
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BRITO, A. C., S. A. S. OLIVEIRA, and E. J. OLIVEIRA. "Genome-wide association study for resistance to cassava root rot." Journal of Agricultural Science 155, no. 9 (October 26, 2017): 1424–41. http://dx.doi.org/10.1017/s0021859617000612.
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SUMMARYCassava root rot (CRR) disease associated with a complex of soil pathogens has caused great yield losses in the crop. The objective of the current work was to obtain insights about the genetic architecture of CRR resistance caused by Fusarium (dry root rot – DRR), Phytophthora (soft root rot – SRR) and Botryosphaeriaceae (black root rot – BRR) species, using genome-wide association studies (GWAS). Phenotyping data of 263 accessions (artificial inoculation) and 14 094 single-nucleotide polymorphisms (SNP) (missing data <0·10 and minor allele frequency >0·05) were used. The severity of CRR in peel and pulp was variable among accessions, but the pathogens that caused DRR were more aggressive. Broad-sense heritability ($h_g^2 $) was of medium magnitude for all groups of resistances for pathogens, with variation from 0·16 ± 0·019 (Fspp Pulp) to 0·31 ± 0·028 (Fspp Peel). The kinship matrix was used to correct for stratification as well as for clustering the accessions. Overall, this analysis showed that there was no relationship between agronomic traits and resistance to CRR and the four clusters obtained from kinship matrix. The GWAS identified 38 significant SNPs, of which eight and 22 are related to the severity of DRR in the pulp and peel, respectively. The other eight SNPs were associated with SRR-peel (1), SRR-pulp (1), BRR-peel (3) and BRR-pulp (3). Half of the SNPs associated with CRR resistance have functional annotations related to defence and response to pathogen attack as well as general cellular processes. The current study revealed that resistance to CRR is controlled by multiple loci with small effects, and significant SNPs can be used to identify putative genes that control these traits.
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Wang, Qing, Stefanie Vera Buxa, Alexandra Furch, Wolfgang Friedt, and Sven Gottwald. "Insights Into Triticum aestivum Seedling Root Rot Caused by Fusarium graminearum." Molecular Plant-Microbe Interactions® 28, no. 12 (December 2015): 1288–303. http://dx.doi.org/10.1094/mpmi-07-15-0144-r.
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Fusarium graminearum is one of the most common and potent fungal pathogens of wheat (Triticum aestivum), known for causing devastating spike infections and grain yield damage. F. graminearum is a typical soil-borne pathogen that builds up during consecutive cereal cropping. Speculation on systemic colonization of cereals by F. graminearum root infection have long existed but have not been proven. We have assessed the Fusarium root rot disease macroscopically in a diverse set of 12 wheat genotypes and microscopically in a comparative study of two genotypes with diverging responses. Here, we show a ‘new’ aspect of the F. graminearum life cycle, i.e., the head blight fungus uses a unique root-infection strategy with an initial stage typical for root pathogens and a later stage typical for spike infection. Root colonization negatively affects seedling development and leads to systemic plant invasion by tissue-adapted fungal strategies. Another major outcome is the identification of partial resistance to root rot. Disease severity assessments and histological examinations both demonstrated three distinct disease phases that, however, proceeded differently in resistant and susceptible genotypes. Soil-borne inoculum and root infection are considered significant components of the F. graminearum life cycle with important implications for the development of new strategies of resistance breeding and disease control.
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Weiland, Jerry E., Carolyn F. Scagel, Niklaus J. Grünwald, E. Anne Davis, Bryan R. Beck, and Jesse N. Mitchell. "Irrigation Frequency and Volume has Little Influence on Phytophthora Root Rot in Container-grown Rhododendron." Journal of Environmental Horticulture 40, no. 2 (June 1, 2022): 67–78. http://dx.doi.org/10.24266/2573-5586-40.2.67.
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Abstract We evaluated whether reducing irrigation frequency and volume alters the ability of Phytophthora plurivora and P. cinnamomi to cause root rot on rhododendron grown in a noninfested potting medium or media infested with 1 or 100 propagules per gram (ppg) of pathogen. Plants were irrigated to maintain a substrate moisture of >70% container capacity (1.0X), one-half volume of 1.0X (0.5X), or two times the volume of 1.0X at each irrigation event for one week, followed by no irrigation, until soil moisture reached <50% container capacity. Aboveground disease symptoms (chlorosis, stomatal conductance, wilting, and plant death) were evaluated weekly and root rot, pathogen presence, plant biomass, and nutrient uptake were measured at the end of each trial. Both pathogens generally caused mild disease at 1 ppg and severe disease at 100 ppg. Reducing irrigation did little to lessen disease caused by either pathogen once infection had occurred. Instead, severe root infection often led to increased soil moisture and root rot across all irrigation treatments as roots became progressively compromised in their ability to take up water. Results show that reducing irrigation after infection has occurred is unlikely to effectively control root rot. Species used in this study: Phytophthora species (Phytophthora cinnamomi Rands; Phytophthora plurivora T. Jung and T.I. Burgess); rhododendron, Rhododendron catawbiense Michx. ‘Album', ‘Roseum Elegans', and ‘Roseum Pink'.
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Swehla, Alyssa, Abhay K. Pandey, and Ramakrishnan M. Nair. "Bioactivity of Trichoderma harzianum isolates against the fungal root rot pathogens with special reference to Macrophomina phaseolina causing dry root rot of mungbean." Indian Phytopathology 73, no. 4 (October 30, 2020): 787–92. http://dx.doi.org/10.1007/s42360-020-00288-x.
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AbstractIn the rice-fallow system, dry root rot (DRR) is an emerging disease of mungbean (Vigna radiata (L.) R. Wilczek var. radiata) caused by the necrotrophic fungus Macrophomina phaseolina. The pathogen causes extensive production losses. In this study, the bioactivity of four Trichoderma harzianum isolates, namely Th-Dharwad, Th-Raichur, Th-Niphm, and Th-Udaipur procured from the Indian research institutes were evaluated against M. phaseolina of mungbean by the dual culture technique. The efficacy of these T. harzianum isolates were also compared with the effective fungicides such as thiram and carbendazim by the poison food method. Results showed that among the T. harzianum isolates, isolate of Th-Raichur was most effective, exhibiting 76.96% mycelial growth inhibition of the test pathogen. As compared to the thiram, carbendazim was more effective, and exhibited 100% mycelial growth inhibition of the test pathogen. In addition, carbendazim was also more effective than the isolate of Th-Raichur. In the sick pot experiment, mungbean seeds treated with Th-Raichur isolate showed a lower percent incidence of DRR (20%) than the untreated seeds (86.6%). The biological spectrum of Th-Raichur isolate was examined against M. phaseolina isolated from the different hosts such as urdbean and vegetable soybean, alongwith two other root pathogens, namely Fusarium solani of mungbean, and Sclerotium rolfsii of urdbean. The isolate of Th-Raichur showed maximum antagonistic activity against the pathogens M. phaseolina and F. solani of mungbean. Thus, Th-Raichur isolate can be used as a potential fungal biocontrol agent for the reduction of DRR in mungbean.
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Liebe, Sebastian, Daniela S. Christ, Ralf Ehricht, and Mark Varrelmann. "Development of a DNA Microarray-Based Assay for the Detection of Sugar Beet Root Rot Pathogens." Phytopathology® 106, no. 1 (January 2016): 76–86. http://dx.doi.org/10.1094/phyto-07-15-0171-r.
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Sugar beet root rot diseases that occur during the cropping season or in storage are accompanied by high yield losses and a severe reduction of processing quality. The vast diversity of microorganism species involved in rot development requires molecular tools allowing simultaneous identification of many different targets. Therefore, a new microarray technology (ArrayTube) was applied in this study to improve diagnosis of sugar beet root rot diseases. Based on three marker genes (internal transcribed spacer, translation elongation factor 1 alpha, and 16S ribosomal DNA), 42 well-performing probes enabled the identification of prevalent field pathogens (e.g., Aphanomyces cochlioides), storage pathogens (e.g., Botrytis cinerea), and ubiquitous spoilage fungi (e.g., Penicillium expansum). All probes were proven for specificity with pure cultures from 73 microorganism species as well as for in planta detection of their target species using inoculated sugar beet tissue. Microarray-based identification of root rot pathogens in diseased field beets was successfully confirmed by classical detection methods. The high discriminatory potential was proven by Fusarium species differentiation based on a single nucleotide polymorphism. The results demonstrate that the ArrayTube constitute an innovative tool allowing a rapid and reliable detection of plant pathogens particularly when multiple microorganism species are present.
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El-kazzaz, Mohamed Kamal, Kamal Elsayed Ghoneim, Mohamed Khaled Mohamed Agha, Asmaa Helmy, Said I. Behiry, Ahmed Abdelkhalek, Muhammad Hamzah Saleem, Abdulaziz A. Al-Askar, Amr A. Arishi, and Mohsen Mohamed Elsharkawy. "Suppression of Pepper Root Rot and Wilt Diseases Caused by Rhizoctonia solani and Fusarium oxysporum." Life 12, no. 4 (April 14, 2022): 587. http://dx.doi.org/10.3390/life12040587.
Full textAbstract:
Pepper is vulnerable to soil-borne fungal pathogens such as Rhizoctonia solani and Fusarium oxysporum. The potential of beneficial rhizosphere microorganisms to control R. solani and F. oxysporum f.sp. capsici was evaluated in pepper plants. Paenibacillus polymyxa and Trichoderma longibrachiatum were isolated from rhizospheric soil samples of healthy pepper plants. In vitro, both isolates caused clear reductions in the radial growth of root rot and wilt pathogens. Scanning electron microscopy displayed lysis and abnormal shape of the pathogens in dual cultures with P. polymyxa and T. longibrachiatum. The incidence and severity of root rot and wilt diseases were significantly reduced in pepper plants treated with the growth-promoting fungi (PGPF isolates; Fusarium equiseti GF19-1, Fusarium equiseti GF18-3, and Phoma sp. GS8-3), P. polymyxa, or T. longibrachiatum in comparison to the control. Moreover, the induction treatments led to increased pepper growth compared with their control. The defense related gene (CaPR4) expression was shown to be significantly higher in the treated plants than in the control plants. In conclusion, the antagonistic isolates (P. polymyxa and T. longibrachiatum) and PGPF isolates have a clear impact on the prevention of root rot and wilt diseases in pepper plants incited by R. solani and F. oxysporum f.sp. capsici. The expression of the CaPR4 gene added to the evidence that PGPF isolates generate systemic resistance to pathogen infections.
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Borowik, Piotr, Tomasz Oszako, Tadeusz Malewski, Zuzanna Zwierzyńska, Leszek Adamowicz, Rafał Tarakowski, Sławomir Ślusarski, and Justyna Anna Nowakowska. "Advances in the Detection of Emerging Tree Diseases by Measurements of VOCs and HSPs Gene Expression, Application to Ash Dieback Caused by Hymenoscyphus fraxineus." Pathogens 10, no. 11 (October 21, 2021): 1359. http://dx.doi.org/10.3390/pathogens10111359.
Full textAbstract:
Ash shoot dieback has now spread throughout Europe. It is caused by an interaction between fungi that attack shoots (Hymenoscyphus fraxineus) and roots (Armillaria spp., in our case Armillaria gallica). While detection of the pathogen is relatively easy when disease symptoms are present, it is virtually impossible when the infestation is latent. Such situations occur in nurseries when seedlings become infected (the spores are carried by the wind several dozen miles). The diseases are masked by pesticides, fertilisers, and adequate irrigation to protect the plants. Root rot that develops in the soil is also difficult to detect. Currently, there is a lack of equipment that can detect root rot pathogens without digging up root systems, which risks damaging trees. For this reason, the use of an electronic nose to detect pathogens in infected tissue of ash trees grown in pots and inoculated with the above fungi was attempted. Disease symptoms were detected in all ash trees exposed to natural infection (via spores) in the forest. The electronic nose was able to detect the pathogens (compared to the control). Detection of the pathogens in seedlings will enable foresters to remove diseased trees and prevent the path from nursery to forest plantations by such selection.
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Golosna, L., G. Lisova, O. Afanasieva, and L. Kucherova. "Resistance of spring wheat cultivars to pathogens of leaf diseases and root rot in the Right-bank Forest Steppe of Ukraine." Interdepartmental Thematic Scientific Collection of Plant Protection and Quarantine, no. 65 (December 20, 2019): 35–50. http://dx.doi.org/10.36495/1606-9773.2019.65.35-50.
Full textAbstract:
Goal. Determine the degree of resistance of spring wheat cultivars to pathogens and root rot in the Right-bank Forest Steppe of Ukraine and identify promising sources of resistance.
Methods. Laboratory — selection of infection material with different levels of virulence, development of infection material of leaf rust and septoria of wheat; field — creation of artificial infection and provocative backgrounds of pathogens and assessment of resistance of the collection of cultivars to this phytopathogens; analytical in mathematical — analysis of the obtained data, calculation of the intensity of disease development.
Results. In 2017—2019, 30 cultivars of spring wheat from the collections of the National Center for Plant Genetic Resources of Ukraine were provided by the Ustimovskaya Plant Research Station of the Institute of Plant Growing. V.Ya. Yuriev NAAS was evaluated for resistance to the main leaf pathogens: powdery mildew Blumeria graminis (DC.) E.O. Speer f. sp. tritici Em. Marchal, brown rust Puccinia recondita f. sp. tritici Rob. et Desm. (syn. Puccinia triticina), leaf septoria Zymoseptoria tritici Rob. et Desm., pyrenophora Pyrenophora tritici-repentis (Died.) Drechsler and root rot. The collection included cultivars of Ukrainian, Russian, Kazakh and Kyrgyz breeding. Assessment of resistance to powdery mildew, pyrenophora and root rot was performed on a natural infectious background, and the pathogens of septoria and leaf rust on the created artificial complex infectious background during the period of maximum disease development. Cultivars were characterized by their degree of stability using a 9 — point immunological scale. According to the research results, the degree of resistance of varieties of Ukrainian and foreign breeding to pathogens of leaf diseases and root rot was established. Among the studied spring wheat collection, a number of cultivars were identified that showed resistance both to individual pathogens and to a group of diseases in the Right-Bank Forest Steppe of Ukraine: to powdery mildew — 4, brown rust — 20, septoria — 8, pyrenophorosis — 8, roots — 7. The group resistance was characterized by 13 spring wheat cultivars.
Conclusions. Valuable sources of resistance are cultivars of Oksamit Mironovsky (UKR) and Lebedushka (RUS) with resistance to the group of pathogens of powdery mildew, leaf rust and pyrenophorosis, characteristic of the Right-Bank Forest Steppe zone of Ukraine. Other spring wheat cultivars that have high resistance to both individual pathogens and their groups are recommended to be involved in the breeding process to create new promising spring wheat cultivars with high resistance rates.
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Kadhim, Wejdan Reiahd, and Ahad A. H. Matloob. "Biological control of fig root rot disease." Journal of Kerbala for Agricultural Sciences 9, no. 3 (September 12, 2022): 139–49. http://dx.doi.org/10.59658/jkas.v9i3.1003.
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The study aimed to isolate and diagnose pathogens of fig root rot disease in addition to evaluation effect of the biological control agents Trichoderma harzianum and Penicillium cyclpium in control of the pathogens of fig root rot. It was found fungi accompanying the roots of fig plantlets. Fusarium solani was the most frequent pathogenic fungus, followed by Rhizoctonia solani. The results showed a high effectiveness of biological agents in inhibiting the growth of pathogenic fungi, as the percentage of inhibition of the fungus T. harzianum against the fungus F. solani reached 100%. The percentage of inhibition against the pathogenic fungus R.solani was 89.99%. As for the bioagent P. cyclopium, the results displayed its high antagonistic ability against the two pathogenic fungi. As well as, the test results revealed the antagonistic ability of the microorganism EM-1 formula against the pathogenic fungi F.solani and R.solani that cause the root rot disease of fig plantlets.
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Parajuli, Madhav, and Fulya Baysal-Gurel. "Control of Phytophthora and Rhizoctonia Root Rot on Red Maple Using Fungicides and Biofungicides." HortScience 57, no. 10 (October 2022): 1306–12. http://dx.doi.org/10.21273/hortsci16673-22.
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Phytophthora nicotianae and Rhizoctonia solani are the well-described soilborne pathogens of concern causing Phytophthora and Rhizoctonia root rot, respectively, of red maple plants (Acer rubrum L.), resulting in substantial economic losses to nursery growers. The management of root and crown rot disease of red maple is a big challenge. The objective of this study was to test the efficacy of several fungicide and biofungicide products to control Phytophthora and Rhizoctonia root rot on red maple plants in greenhouse conditions. Treatments, including fungicides and biofungicides, and nontreated and inoculated and nontreated and noninoculated as controls were arranged in a completely randomized design with six replications. Red maples planted in number 1 nursery containers were artificially inoculated with P. nicotianae or R. solani. Plant height, plant width, total fresh weight, and root fresh weight were measured and roots were assessed for root rot disease severity based on a scale of 0% to 100% root damaged. The pathogen recovery percentage of plant roots was determined by culturing ten randomly selected root pieces (≈1 cm long) cut from the root tips on Phytophthora selective medium (PARPH-V8) or Rhizoctonia semi-selective medium. All tested fungicides and biofungicides reduced Phytophthora and Rhizoctonia root rot on red maple plants compared with the nontreated and inoculated control. Likewise, pathogen recovery was lower for fungicide-treated and biofungicide-treated plants. Fungicides, such as mefenoxam, oxathiapiprolin, pyraclostrobin plus boscalid, and pyraclostrobin provided the most effective control of Phytophthora root rot. Pyraclostrobin plus boscalid and pyraclostrobin followed by biofungicides Bacillus amyloliquefaciens strain F727 and Trichoderma harzianum Rifai strain T-22 plus T. virens strain G-41 were most effective for suppressing Rhizoctonia root rot. There were no differences in plant height, plant width, plant fresh weight, and root fresh weight among the treatments. These findings will help nursery producers make decisions while formulating soilborne disease management strategies for red maple production.
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Bilgi, V. N., C. A. Bradley, F. M. Mathew, S. Ali, and J. B. Rasmussen. "Root Rot of Dry Edible Bean Caused by Fusarium graminearum." Plant Health Progress 12, no. 1 (January 2011): 14. http://dx.doi.org/10.1094/php-2011-0425-01-rs.
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Fusarium graminearum was identified as a root pathogen of a diverse array of dry edible bean genotypes under both field and greenhouse conditions in North Dakota. In comparisons under controlled conditions, root rot caused by F. graminearum was equal or greater than that caused by F. solani f. sp. phaseoli. Out of eleven dry bean genotypes evaluated in controlled conditions, Eclipse, VAX 3, and T-39 had the lowest root rot severity values for both F. graminearum and F. solani f. sp. phaseoli. A significant and positive correlation between genotype response to F. graminearum and F. solani f. sp. phaseoli indicates that genetic resistance to both pathogens may be related. Accepted for publication 2 March 2011. Published 25 April 2011.
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Fan, Wen Zhong. "Identification and Biological Characteristics of Strawberry Root Rot Pathogen." Applied Mechanics and Materials 312 (February 2013): 857–61. http://dx.doi.org/10.4028/www.scientific.net/amm.312.857.
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By research on strawberry root rot germ in several bases of Jilin province, cleared that the pathogen of strawberry root rot mainly were F. oxysporum and Rhizoctonia solani Kuhn, the growth of F. oxysporum was the best when took sucrose as C source, and the growth of Rhizoctonia solani Kuhn was the best when took starch as C source. KNO3 was the most appropriate N source to their growth. The effect of light on F. oxysporum was not great, but on Rhizoctonia solani Kuhn was great, the growth of mycelium was the fastest under alternating light and dark conditions, and had inhibition under full light conditions. Acidic conditions were suitable for mycelium growth of F. oxysporum, and the growth speed of both pathogens was the highest when PH was 6.
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María de Jesús, Ramírez-Ramírez, N. Alejandra Mancilla-Margalli, Meza-Álvarez Lucía, Turincio-Tadeo Ramón, Pena Doralinda Guzmán-de, and Avila-Miranda Martin Eduardo. "Epidemiology of Fusarium agave wilt in Agave tequilana Weber var. azul." Plant Protection Science 53, No. 3 (May 28, 2017): 144–52. http://dx.doi.org/10.17221/142/2016-pps.
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Fusarium oxysporum is reported as the principal causal agent limiting production of Agave tequilana Weber var. azul, but frequent isolation of F. solani, and symptoms typical of F. solani as a pathogen like severe reddish coloured root rot and loss of soil anchorage are frequently associated with diseased agaves. Inoculations of agave plantlets with F. solani induced typical agave root rot symptoms in greenhouse trials. The incidence of both pathogens was determined molecularly with specific primers in the ITS2 sequence. Dispersion patterns of agave wilt, determined in plantations of different age, indicated a tendency to produce aggregated patterns over time as the disease spread from the initial symptomatic plant to adjacent plants. Although both fungi were isolated from agave diseased plants, and in spite of the higher percentage of detection and root rot symptoms, it is concluded that F. solani may have a greater impact in agave wilt.
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Karadimos, Dimitros, and George Karaoglanidis. "Survey of root rot diseases of sugar bett in Central Greece." Zbornik Matice srpske za prirodne nauke, no. 110 (2006): 129–31. http://dx.doi.org/10.2298/zmspn0610129k.
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An extensive survey was conducted during the summer and autumn of 2004 in sugar beet fields in the area of Larissa, Thessaly region, with plants showing symptoms of root rot diseases. The aim of the monitoring was to identify the causal agents of root rot diseases. In total, 76 sugar beet fields were surveyed and 5-10 diseased roots were examined from each field. Isolations, carried out on PDA, showed that two main fungal pathogens causing root rot were Rhizoctonia solani and Phytophthora cryptogea. The former was isolated in 46% of the fields and the latter in 38% of the fields. In addition, Rhizopus stolonifer, Fusarium spp., Scerotium rolfsii and Rhizoctonia violacea were isolated in 14%, 7%, 4% and 1% of the fields respectively. In most of the surveyed fields only one pathogen species was isolated and only in a few of them more than one fungal species was identified.
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Jacobs, Janette L., James D. Kelly, Evan M. Wright, Gregory Varner, and Martin I. Chilvers. "Determining the Soilborne Pathogens Associated with Root Rot Disease Complex of Dry Bean in Michigan." Plant Health Progress 20, no. 2 (January 1, 2019): 122–27. http://dx.doi.org/10.1094/php-11-18-0076-s.
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In Michigan, yield reduction as a result of diminished plant vigor owing to root rot is a major constraint associated with dry bean production and is exacerbated when fields have a history of short crop rotations. Replanting can be necessary when flooding, poor seed germination, or cool soil temperatures result in poor plant establishment, which may be compounded by increased disease pressure. To identify which soilborne pathogens are associated with root rot disease complex on dry bean and to determine their prevalence, a survey was conducted from 2014 to 2018. Dry beans with root rot symptoms were obtained from 39 field locations in 10 counties in Michigan. Rotted roots were washed, potential pathogens were cultured, and isolates were putatively identified into the major pathogen groups based on morphology. Additional identification was conducted with sequencing of the internal transcribed spacer of rDNA for oomycetes and Rhizoctonia and the translation elongation factor 1-α gene for Fusarium isolates. Among the 1,034 isolates obtained, Fusarium (54%) was recovered at the highest prevalence, and oomycetes and Rhizoctonia exhibited a consistent presence, ranging across years from 11 to 30.2% and from 9.3 to 41.8%, respectively. This survey provided baseline information on the prevalence of critical soilborne pathogens of dry bean in Michigan. In the future, additional genetic markers will be utilized to further identify organisms, a species characterization will be conducted to assess pathogenicity and virulence, and dry bean germplasm will be screened for resistance.
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Sealy, Ramsey, and Michael R. Evans. "EFFICACY OF BIOLOGICAL AMENDMENTS ON POSTTRANSPLANT ROOT ROT." HortScience 40, no. 3 (June 2005): 880b—880. http://dx.doi.org/10.21273/hortsci.40.3.880b.
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Biological substrate amendments including SG-11, Subtilex, SoilGuard, ActinoIron, Companion, RootShield and BioYield were evaluated for their efficacy to control common soil-borne fungal and fungal-like pathogens when incorporated into the substrate at transplanting. The biological agents were incorporated into an 80% Sphagnum peat and 20% perlite substrate at the label recommended rates and four-to-six-leaf plugs of the test species were transplanted into the substrates. Substrates were either inoculated or uninoculated with a test pathogen. Pathogen-host combinations included Pythium ultimum on geranium (Pelargonium ×hortorum), Phytophthora nicotianae and Pythium aphanidermatum on vinca (Catharanthus roseus), and Theilaviopsis basicoli on pansy (Viola ×wittrockiana). The incidence of disease development, plant mortality and root fresh weights did not differ among the biological agents and the inoculated controls. Therefore, under the conditions of this study, the biological agents did not provide significant disease suppression. Pansy and vinca plants grown in uninoculated substrates amended with Subtilex had significantly higher shoot dry weights than those grown in unamended substrates. Pansy, vinca and tomato plants grown in uninoculated substrates amended with SG-11 had significantly higher shoot dry weights than those grown in unamended substrates.
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Kurze, Stefan, Hubert Bahl, Robert Dahl, and Gabriele Berg. "Biological Control of Fungal Strawberry Diseases by Serratia plymuthica HRO-C48." Plant Disease 85, no. 5 (May 2001): 529–34. http://dx.doi.org/10.1094/pdis.2001.85.5.529.
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To develop a biological control product for commercial strawberry production, the chitinolytic rhizobacterium Serratia plymuthica strain HRO-C48 was evaluated for plant growth promotion of strawberries and biological control of the fungal pathogens Verticillium dahliae and Phytophthora cactorum. In phytochamber experiments, treatment with S. plymuthica HRO-C48 resulted in a statistically significant enhancement of plant growth dependent on the concentration of the bacterium that was applied. In greenhouse trials, bacterial treatment reduced the percentage of Verticillium wilt (18.5%) and Phytophthora root rot (33.4%). In three consecutive vegetation periods, field trials were carried out in soil naturally infested by both soilborne pathogens on commercial strawberry farms located in various regions of Germany. Dipping plants in a suspension of S. plymuthica prior to planting reduced Verticillium wilt compared with the nontreated control by 0 to 37.7%, with an average of 24.2%, whereas the increase of yield ranged from 156 to 394%, with an average of 296%. Bacterial treatment reduced Phy-tophthora root rot by 1.3 to 17.9%, with an average of 9.6%, and increased strawberry yield by 60% compared with the nontreated control. Under field conditions, strain HRO-C48 survived at approximately log10 3 to 7 CFU/g of root in the strawberry rhizosphere at 14 months after root application. Although results of the field trials were influenced by pathogen inoculum density, cropping history of the field site, and weather conditions, S. plymuthica HRO-C48 successfully controlled wilt and root rot of strawberry.
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Coetzee, Martin, Brenda Wingfield, and Michael Wingfield. "Armillaria Root-Rot Pathogens: Species Boundaries and Global Distribution." Pathogens 7, no. 4 (October 24, 2018): 83. http://dx.doi.org/10.3390/pathogens7040083.
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This review considers current knowledge surrounding species boundaries of the Armillaria root-rot pathogens and their distribution. In addition, a phylogenetic tree using translation elongation factor subunit 1-alpha (tef-1α) from isolates across the globe are used to present a global phylogenetic framework for the genus. Defining species boundaries based on DNA sequence-inferred phylogenies has been a central focus of contemporary mycology. The results of such studies have in many cases resolved the biogeographic history of species, mechanisms involved in dispersal, the taxonomy of species and how certain phenotypic characteristics have evolved throughout lineage diversification. Such advances have also occurred in the case of Armillaria spp. that include important causal agents of tree root rots. This commenced with the first phylogeny for Armillaria that was based on IGS-1 (intergenic spacer region one) DNA sequence data, published in 1992. Since then phylogenies were produced using alternative loci, either as single gene phylogenies or based on concatenated data. Collectively these phylogenies revealed species clusters in Armillaria linked to their geographic distributions and importantly species complexes that warrant further research.