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Sulaiman, Adel, Vatsala Anand, Sheifali Gupta, Hani Alshahrani, Mana Saleh Al Reshan, Adel Rajab, Asadullah Shaikh, and Ahmad Taher Azar. "Sustainable Apple Disease Management Using an Intelligent Fine-Tuned Transfer Learning-Based Model." Sustainability 15, no. 17 (September 4, 2023): 13228. http://dx.doi.org/10.3390/su151713228.
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Apple foliar diseases are a group of diseases that affect the leaves of apple trees. These diseases can significantly impact apple tree health and fruit yield. Ordinary apple foliar diseases include frog_eye_leaf_spots, powdery mildew, rust, apple scabs, etc. Early detection of these diseases is important for effective apple crop management to increase the yield of apples. Therefore, this research proposes a fine-tuned EfficientNetB3 model for the quick and precise assessment of these apple foliar diseases. A dataset containing 23,187 RGB images of eleven different apple foliar diseases is used for experimentation. The proposed model is compared with four transfer learning models, i.e., InceptionResNetV2, ResNet50, AlexNet, and VGG16. All models are fine-tuned by adding different layers like the global average pooling layer, flatten layer, dropout layer, and dense layer. The performance of these five models is compared in terms of the precision, recall, accuracy, and F1-score. The EfficientNetB3 outperformed the other models in terms of all performance parameters. The best model is further optimized with the help of three optimizers, i.e., Adam, SGD, and Adagrad. The proposed model achieved the precision, recall, and F1-score values of 86%, 88%, and 86%, respectively, at 32 batch sizes and 10 epochs. This research formulated a model for an apple foliar disease diagnosis within sustainable agriculture.
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Charan, Merugu Sai, Mohammed Abrar, and Bejjam Vasundhara Devi. "Apple Leaf Diseases Classification Using CNN with Transfer Learning." International Journal for Research in Applied Science and Engineering Technology 10, no. 6 (June 30, 2022): 1905–12. http://dx.doi.org/10.22214/ijraset.2022.44176.
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Abstract: The Foliar diseases of the apple trees commonly reduce the crop Yield and photosynthesis which affects their productivity. Diagnosing foliar damage is not easy if there are no distinct patterns that would be fungal fruiting bodies it will. spread to the rest of the crops. The foliar disease of the apple trees is carried out due to biotic and abiotic causes, some of the biotic causes of foliar damage are - Bacterial Disease, Fungal Diseases, Viral Diseases, Insects, and Mites That Damage Foliage. some of the Abiotic causes are - Iron Chlorosis, Misapplied Herbicide, and Winter Desiccation of Evergreens. Traditional approaches rely on visual inspection by an expert and biological examination is the second choice .these approaches are time-consuming and expensive. we use machine learning methods to classify the disease in apple trees. we use some pre-trained CNN models to extract features from the dataset, we applied the CNN model and compared them with Pre-trained Models, and we achieve accuracies of over 93% with CNN, among the Models We achieved 92% with the Inception V3 model,62% with VGG16, 63% with VGG19.
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Ashritha, K., K. Sandhya, Y. Uday Kiran, and V. N. L. N. Murthy. "Plant-Leaf Disease Prediction Using Deep Learning." International Journal for Research in Applied Science and Engineering Technology 11, no. 3 (March 31, 2023): 121–28. http://dx.doi.org/10.22214/ijraset.2023.49338.
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Abstract: Brown spot, Mosaic, Grey spot, and Rust all significantly reduce apple yield. Rust is a sign of Foliar illness in this instance. The primary factor influencing apple output is the occurrence of apple leaf diseases, which results in significant yearly economic losses. Therefore, it is very important to research apple leaf disease identification. Plants are frequently attacked by pests, bacterial diseases, and other microorganisms. Inspection of the leaves, stem, or fruit usually identifies the attack's signs. Powdery Mildew and Leaf Blight are two common plant diseases that can cause severe harm if not treated quickly. In the realm of agriculture, image processing is frequently utilized for classification, detection, grading, and quality control. Finding and identifying plant diseases is crucial, especially when trying to produce fruit of the highest caliber. The real-time identification of apple leaf diseases is addressed in this research using a deep learning strategy that is based on enhanced convolutional neural networks (CNNs). This study uses data augmentation and image annotation tools to create the foliar disease dataset, which is made up of complex images captured in the field and laboratories. Overall, we can identify the illness present in plants on a massive scale by utilizing machine learning to train the vast data sets that are publically available. The project explains how to identify plant leaf diseases, how they affect plant yield, and which pesticides should be used to treat them. in agriculture. To monitor huge plant fields and automatically identify disease symptoms as soon as they develop on plant leaves, research on automatic plant disease is crucial. In this essay, we'll demonstrate how to identify plant illnesses by obtaining photos of their leaves
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Blaedow, Ryan, William Chaney, Paul Pecknold, and Harvey Holt. "Investigation of Fungicidal Properties of the Tree Growth Regulator Paclobutrazol to Control Apple Scab." Arboriculture & Urban Forestry 32, no. 2 (March 1, 2006): 67–73. http://dx.doi.org/10.48044/jauf.2006.009.
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Paclobutrazol (PBZ) as a systemic fungicide for control of apple scab (Venturia inaequalis) was investigated in mature (cv. Hopa and Snow Drift) and young sapling (cv. Indian Magic) crabapples (Malus spp.). Treatments consisted of a control and PBZ applied to mature trees at one or two times the recommended rate in April 2002 using the basal drench method. Saplings received either foliar or soil drench applications of PBZ, or foliar applications of propiconazole. Disease assessments of mature trees showed that apple scab symptoms in treated trees were as severe as in untreated ones in the year of treatment but were reduced slightly the year after treatment in ‘Hopa’ and the third year after treatment in ‘Snow Drift.’ Growth reduction occurred in all treated trees, suggesting that the PBZ levels needed for growth reduction were not sufficient to control apple scab in the year of treatment. In contrast, a one-time foliar application of PBZ reduced apple scab incidence to levels found in ‘Indian Magic’ saplings treated every 2 weeks with propiconazole, a fungicide and application method commonly recommended for apple scab control. Delayed uptake and insufficient transport of PBZ to the foliage of mature trees after root drench treatments may account for the lack of apple scab control in the years after treatment, even though growth suppression occurred.
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Hirakue, Ayumi, and Shuichi Sugiyama. "Relationship between foliar endophytes and apple cultivar disease resistance in an organic orchard." Biological Control 127 (December 2018): 139–44. http://dx.doi.org/10.1016/j.biocontrol.2018.09.007.
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Peng, H. X., X. Y. Wei, Y. X. Xiao, Y. Sun, A. R. Biggs, M. L. Gleason, S. P. Shang, M. Q. Zhu, Y. Z. Guo, and G. Y. Sun. "Management of Valsa Canker on Apple with Adjustments to Potassium Nutrition." Plant Disease 100, no. 5 (May 2016): 884–89. http://dx.doi.org/10.1094/pdis-09-15-0970-re.
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Valsa canker, caused by the fungus Valsa mali, is one of the most destructive diseases of apple in the primary production areas of China and other East Asian countries. Currently, there are no effective control methods for this disease. We investigated the occurrence of Valsa canker in 24 apple orchards in Shaanxi Province in concert with foliar nutrient analysis, and found that there was a significant negative correlation of leaf potassium (K) content with incidence and severity of Valsa canker. Fertilization experiments showed that increasing tree K content enhanced resistance to pathogen colonization and establishment. Apple trees with leaf K content greater than 1.30% exhibited almost complete resistance to Valsa mali. Field trials demonstrated that increasing K fertilization could significantly reduce disease incidence. Improved management of tree nutrition, especially K content, could effectively control the occurrence and development of Valsa canker.
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Prokopy, Ronald J. "A LOW-SPRAY APPLE-PEST-MANAGEMENT PROGRAM FOR SMALL ORCHARDS." Canadian Entomologist 117, no. 5 (May 1985): 581–85. http://dx.doi.org/10.4039/ent117581-5.
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AbstractFrom 1981 to 1984, a low-spray management program was employed against injurious arthropods on the 40 disease-resistant apple trees in my experimental orchard in Massachusetts. The program consisted of an annual early-season application of petroleum oil followed by 2 applications of phosmet (1 at petal fall and another 10–14 days later). Visual traps were used to suppress Rhagoletis pomonella flies. For all years combined, a mean of 89.7% of fruit sampled at harvest in this orchard was free of insect injury compared with 0% uninjured fruit on neighboring unsprayed trees. Populations of foliar-feeding pests never reached injurious levels.
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Percival, Glynn. "The Influence of Inducing Agents Applied by Soil Drenches on Disease Severity of Apple and Pear Scab." Arboriculture & Urban Forestry 46, no. 5 (September 1, 2020): 358–70. http://dx.doi.org/10.48044/jauf.2020.026.
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Apple and pear scab are foliar diseases of ornamental and fruiting apple and pear trees. Unmanaged, yield and aesthetic losses can be severe. Overreliance on synthetic fungicides means novel means of disease management are required. Field trials were conducted using apple (Malus cv. Crown Gold) and pear (Pyrus communis ‘Williams Bon Chrétien’) to assess the efficacy of a range of commercially available inducing resistance (IR) agents (harpin protein, potassium phosphite, salicylic acid derivative, and chitosan) as root drenches against both scab diseases. A synthetic fungicide (penconazole) spray program used within the UK for apple and pear scab control was included for comparison. Each IR agent was applied four times, (i) before the visible appearance of scab (April through June, i.e., preventatively) or (ii) after symptoms of scab were visibly observed (June through August, i.e., curatively). Limited efficacy as scab protectants was demonstrated when IR agents were applied curatively. Likewise, limited efficacy was recorded when IR agents were applied once or twice as a preventative measure. However, when IR agents were applied as root drenches greater or equal to three times, efficacy as scab protectants was confirmed (increased leaf chlorophyll content, increased fruit yield, reduced leaf and fruit scab severity). A synthetic fungicide penconazole spray program provided the greatest protection against apple and pear scab in all trials when sprayed preventatively rather than curatively. Results suggest application of at least three root drenches from April through June with an appropriate IR agent provides a useful addition to existing methods of apple and pear scab management under field conditions.
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Rebel, P., C. Poblete-Echeverría, J. G. van Zyl, J. P. B. Wessels, C. Coetzer, and A. McLeod. "Determining Mancozeb Deposition Benchmark Values on Apple Leaves for the Management of Venturia inaequalis." Plant Disease 104, no. 1 (January 2020): 168–78. http://dx.doi.org/10.1094/pdis-04-19-0873-re.
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Apple scab, caused by Venturia inaequalis, is the most common fruit and foliar disease in commercial apple production worldwide. Early in the production season, preventative contact fungicide sprays are essential for protecting highly susceptible continuously unfolding and expanding young leaves. In South Africa, mancozeb is a key contact fungicide used for controlling apple scab early in the season. The current study developed deposition benchmarks indicative of the biological efficacy of mancozeb against apple scab, using a laboratory-based apple seedling model system. The model system employed a yellow fluorescent pigment that is known to be an effective tracer of mancozeb deposition. A concentration range of mancozeb (0.15 to 1 times the registered dosage) and fluorescent pigment concentrations was sprayed onto seedling leaves, which yielded various fluorescent particle coverage (FPC%) levels. Modeling of the FPC% values versus percent disease control yielded different benchmark values when disease quantification was conducted using two different methods. Thermal infrared imaging (TIRI) disease quantification resulted in a benchmark model where 0.40%, 0.79%, and 1.35 FPC% yielded 50, 75, and 90% apple scab control, respectively. These FPC% values were higher than the benchmarks (0.10, 0.20, and 0.34 FPC%, respectively) obtained with quantitative real-time PCR (qPCR) disease quantification. The qPCR benchmark model is recommended as a guideline for evaluating the efficacy of mancozeb sprays on leaves in apple orchards since the TIRI benchmark model underestimated disease control. The TIRI benchmark model yielded 68% disease control at the lowest mancozeb dosage, yet no visible lesion developed at this dosage. Both benchmark models showed that mancozeb yielded high levels of disease control at very low concentrations; for the qPCR benchmark model the FPC% value of the FPC90 (90% control) corresponded to 0.15 times that of the registered mancozeb concentration in South Africa, i.e., 85% lower than the registered dosage.
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Prokopy, Ronald J., Daniel R. Cooley, Wesley R. Autio, and William M. Coli. "Second-level integrated pest management in commercial apple orchards." American Journal of Alternative Agriculture 9, no. 4 (December 1994): 148–56. http://dx.doi.org/10.1017/s0889189300005890.
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AbstractAs historical background helpful to understanding current concepts and practices of apple pest management, we review the origin and rise of key pests of apple in North America and the evolution of approaches to their management, culminating with the concept of integrated pest management (IPM). We propose four levels of integration of orchard pest management practices. First-level IPM integrates chemically based and biologically based management tactics for a single class of pests, such as arthropods, diseases, weeds or vertebrates. Second-level IPM, the focus of our effort here, integrates multiple management tactics across all classes of pests. We describe components of second-level IPM for Massachusetts apple orchards, which are threatened each year by an exceptionally broad range of injurious pests. We illustrate the tentative advantages and shortcomings of second-level IPM using 1993 data from six commercial orchard test blocks. Our predominant approach was to use chemically based tactics for controlling arthropods, diseases and weeds early in the growing season, and afterwards to rely exclusively (for insects) or largely (for other pests) on biologically based tactics, such as cultural, behavioral, and biological controls. Compared with nearby first-level IPM blocks, insecticide use in 1993 was reduced substantially (about 30%), with only slightly more insect injury to fruit and little difference in populations of foliar insect pests. The results for mite pests and diseases were less encouraging although summer pruning significantly reduced disease injury caused by flyspeck. We discuss how second-level IPM poses special biological or operational challenges to apple pest management practitioners. The concept has merit, but refinements are necessary before it can be recommended broadly to commercial apple growers in Massachusetts as an economical and reliable alternative to first-level IPM.
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Grinbergs, D., J. Chilian, J. Carrasco-Fernández, A. France, E. Moya-Elizondo, and M. Gerding. "A PCR-Based Method for the Rapid Detection of Chondrostereum purpureum in Apple." Plant Disease 104, no. 3 (March 2020): 702–7. http://dx.doi.org/10.1094/pdis-10-19-2086-re.
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Silverleaf caused by the basidiomycete Chondrostereum purpureum affects numerous woody species, including fruit tree crops like apple, resulting in wood necrosis and foliar silvering. There are no curative alternatives for this disease, and its management is by prevention methods. Therefore, the aim of this study was to develop a rapid diagnostic tool for the detection and identification of C. purpureum directly from woody tissues to help distinguish the pathogen from other basidiomycetes that are commonly found on apple. The silverleaf pathogen was isolated from different hosts and locations, and Koch’s postulates were performed by inoculating the isolates on apple cuttings and measuring internal necrosis. A previously described APN 1 pair of primers specificity was also tested against 25 C. purpureum isolates in this study, using other wood rotting species as negative controls. Seven virulent isolates were inoculated on apple cuttings, and DNA was extracted from the cuttings’ sawdust and amplified using APN 1, after 22 days of incubation. To prove the efficiency of the method in the field, DNA from healthy nursery plants inoculated with two virulent isolates, and naturally infected plants showing different levels of foliar symptoms, were tested. Presence of the fungus was verified by reisolation on APDA in all assays. Koch’s postulates indicated that all C. purpureum isolates were pathogenic, showing different virulence levels, and APN 1 primers were able to discriminate them from other basidiomycetes. The method was also able to detect C. purpureum from artificially inoculated plants as well as naturally infected ones, demonstrating that the protocol may become a rapid minimally destructive diagnostic tool to detect the pathogen without the need to isolate it from tissues, and thus taking measures to prevent its dissemination.
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Williams, Mark A., John G. Strang, Ricardo T. Bessin, Derek Law, Delia Scott, Neil Wilson, Sarah Witt, and Douglas D. Archbold. "An Assessment of Organic Apple Production in Kentucky." HortTechnology 25, no. 2 (April 2015): 154–61. http://dx.doi.org/10.21273/horttech.25.2.154.
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Although the interest in and production acreage of organic fruit and vegetables has grown in recent years, there are questions about the viability of perennial crops such as apple (Malus ×domestica) in an organic system in Kentucky because of the long, hot, and humid growing season. Thus, the objective of this project was to assess the severity of the challenges to organic apple production in Kentucky. A high-density, organic apple orchard was established in 2007 in the University of Kentucky Horticultural Research Farm in Lexington. The orchard of apple scab (Venturia inaequalis)–resistant ‘Redfree’, ‘Crimson Crisp’, and ‘Enterprise’ trees on ‘Budagovsky 9’ (B.9) rootstock, trained in a vertical axis system, was managed using organically certified techniques and materials for disease and insect control since its inception. Tree growth, tree and fruit injury from insect pests and diseases, and yield over the period 2011–13 were studied. Periodic, shallow cultivation kept the ground beneath the trees free of vegetation once the lower limbs were pulled up and away from the path of the equipment. Vole (Microtus sp.) damage was a continuing problem despite the use of trunk guards and cultivation to remove habitat around the trees. Total fruit yield ranged from 1.2 to 8.1 kg/tree across years and cultivars, with the marketable proportion of the total yield averaging 68% for Redfree and 43% for Crimson Crisp and Enterprise over the 3-year period. The unmarketable fruit exhibited a high incidence of plum curculio (Conotrachelus nenuphar) damage, with generally less damage from codling moth (Cydia pomonella) and sooty blotch (Glosodes pomigena)/flyspeck (Schizathyrium pomi). In addition, in two of the three seasons, ‘Crimson Crisp’ and ‘Enterprise’, which were harvested at later calendar dates then ‘Redfree’, had significant levels of powdery mildew (Podosphaera leucotricha) injury, ‘Enterprise’ had significantly greater bitter rot (Glomerella cingulata), and ‘Crimson Crisp’ showed fruit and foliar damage from cedar apple rust (Gymnosporangium juniperi-virginianae). Because ‘Redfree’ was the only cultivar with an acceptable marketable proportion of the fruit crop, the use of early ripening disease-resistant apple cultivars may have the greatest potential for successful organic apple production in Kentucky and the surrounding region.
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Meng, Yanan, Mark L. Gleason, Rong Zhang, and Guangyu Sun. "Genome Sequence Resource of the Wide-Host-Range Anthracnose Pathogen Colletotrichum siamense." Molecular Plant-Microbe Interactions® 32, no. 8 (August 2019): 931–34. http://dx.doi.org/10.1094/mpmi-01-19-0010-a.
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Colletotrichum siamense causes fruit or foliar disease called anthracnose on a variety of plant hosts such as vegetables, fruits, ornamental plants, and others, including chili pepper, apple, American cranberry, mango, orange, papaya, guava, rubber plant, jasmine, coffee berry, and tea plants. Here, we report the first Illumina-sequenced draft genome assembly of C. siamense strain ICMP 18578 and its annotation. This genome sequence provides a unique resource that will be useful for future research on the evolution of Colletotrichum spp. and improvement of anthracnose management strategies.
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Hemmat, Minou, Susan K. Brown, and Norman F. Weeden. "Tagging and Mapping Scab Resistance Genes from R12740-7A Apple." Journal of the American Society for Horticultural Science 127, no. 3 (May 2002): 365–70. http://dx.doi.org/10.21273/jashs.127.3.365.
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The genetic basis of resistance to apple scab [Venturia inaequalis (Cke.) Wint.] in the Russian apple seedling R12740-7A (Malus Mill. sp.) was investigated. Segregation ratios obtained in crosses with susceptible cultivars suggested that at least two genes were involved, and three foliar resistance reactions (chlorotic, stellate necrotic, and pit type) were observed after inoculation. DNA markers were identified for both the stellate necrotic (Vr) and pit type (no locus designation, Vx suggested) resistance phenotypes. Comparison of resistance phenotypes with marker segregation demonstrated that only two major dominant genes were present in R12740-7A, one producing the stellate necrotic lesion and the other the pit-type lesion. The chlorotic lesion could be attributed to either unclear expression of the resistance phenotype or to susceptible genotypes not contracting the disease. These markers along with a previously published marker for Vf were used to analyze inheritance of resistance in a Vr × Vf cross in advanced breeding material. The markers identified successfully all susceptible progeny, as well as apparent escapes and individuals possessing both Vf and Vr. Thus, the markers should be useful in future screening of segregating progeny and in the pyramiding of scab resistance genes in new cultivars.
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Boyd-Wilson, K. S. H., R. C. Butler, and M. Walter. "Calcium chloride against black spot on apples." New Zealand Plant Protection 63 (August 1, 2010): 279. http://dx.doi.org/10.30843/nzpp.2010.63.6592.
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Calcium chloride which is classified as generally recognised as safe (GRAS) under the Agricultural Compounds and Veterinary Medicines Regulations 2001 has potential for use in an organic apple production system against black spot (Venturia inaequalis) The effectiveness of calcium chloride on control of black spot was evaluated in a field trial over the 2007/2008 growing season Calcium chloride was applied 10 times over the season at the commerciallyrecommended rate of 033 kg product/100 litres or at 2 kg/100 litres (the latter treatment was halved after two applications due to foliar damage) At harvest fruit treated with the high rate of calcium chloride had a lower disease incidence of 41 than the water control which had 97 incidence (P
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Liu, Bo-Yuan, Ke-Jun Fan, Wen-Hao Su, and Yankun Peng. "Two-Stage Convolutional Neural Networks for Diagnosing the Severity of Alternaria Leaf Blotch Disease of the Apple Tree." Remote Sensing 14, no. 11 (May 24, 2022): 2519. http://dx.doi.org/10.3390/rs14112519.
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In many parts of the world, apple trees suffer from severe foliar damage each year due to infection of Alternaria blotch (Alternaria alternata f. sp. Mali), resulting in serious economic losses to growers. Traditional methods for disease detection and severity classification mostly rely on manual labor, which is slow, labor-intensive and highly subjective. There is an urgent need to develop an effective protocol to rapidly and accurately evaluate disease severity. In this study, DeeplabV3+, PSPNet and UNet were used to assess the severity of apple Alternaria leaf blotch. For identifications of leaves and disease areas, the dataset with a total of 5382 samples was randomly split into 74% (4004 samples) for model training, 9% (494 samples) for validation, 8% (444 samples) for testing and 8% (440 samples) for overall testing. Apple leaves were first segmented from complex backgrounds using the deep-learning algorithms with different backbones. Then, the recognition of disease areas was performed on the segmented leaves. The results showed that the PSPNet model with MobileNetV2 backbone exhibited the highest performance in leaf segmentation, with precision, recall and MIoU values of 99.15%, 99.26% and 98.42%, respectively. The UNet model with VGG backbone performed the best in disease-area prediction, with a precision of 95.84%, a recall of 95.54% and a MIoU value of 92.05%. The ratio of disease area to leaf area was calculated to assess the disease severity. The results showed that the average accuracy for severity classification was 96.41%. Moreover, both the correlation coefficient and the consistency correlation coefficient were 0.992, indicating a high agreement between the reference values and the value that the research predicted. This study proves the feasibility of rapid estimation of the severity of apple Alternaria leaf blotch, which will provide technical support for precise application of pesticides.
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Sholberg, P. L., and J. Boulé. "Palmolive® detergent controls apple, cherry, and grape powdery mildew." Canadian Journal of Plant Science 89, no. 6 (November 1, 2009): 1139–47. http://dx.doi.org/10.4141/cjps09017.
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Palmolive® detergent applied in water was compared with the standard fungicide treatment for control of powdery mildew on apple [Podosphaera leucotricha (Ell. & Ev.) E.S. Salmon], cherry [P. clandestina (Wall.:Fr.) Lév.], and grape [Erysiphe necator (Schw.) Burrill]. Initial tests in the greenhouse with apple and grape seedlings showed that Palmolive® was as effective as myclobutanil in preventing powdery mildew on leaves. In apple orchard trials conducted in 2004, 2005 and 2006 Palmolive® detergent prevented powdery mildew on leaves, but caused fruit russetting when used at a rate higher than 5 mL L-1 through the growing season. The 10 mL L-1 rate reduced foliar powdery mildew in an apple and cherry nursery and in Pinot noir grapes, but caused russetting on grape berries. Further studies to determine optimum rates and spray timing will be required before it can be used safely on grapes. Studies on activity of Palmolive® detergent on Cameo apple leaves showed that it had protectant, eradicant, and antisporulant properties comparable with myclobutanil if applied within 1 d before or after inoculation with P. leucotricha and had superior antisporulant properties when applied to 7-d-old lesions. Palmolive® detergent, if used appropriately, could be an important component of an IPM strategy for control of powdery mildew on apple, cherry, and grape because it presents very little risk for the development of fungicide resistance. Key words: Pest management, plant disease, orchard, vineyard
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Gur, Lior, Moshe Reuveni, and Yigal Cohen. "Phenology-Based Management of Alternaria Fruit Rot in Pink Lady Apples." Plant Disease 102, no. 6 (June 2018): 1072–80. http://dx.doi.org/10.1094/pdis-05-17-0735-re.
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Fruit body rot and calyx rot caused by Alternaria alternata f. sp. mali has recently become a severe disease of Pink Lady apple in Israel. Severe fruit rot caused by A. alternata f. sp. mali has not been reported elsewhere in the world, and control measures are not currently known. Our objective was to determine the peak periods of susceptibility and develop methods to manage the disease by timing fungicide applications according to fruit phenological stage. We determined the relationship between fruit phenological stage and rot susceptibility by (i) monitoring the appearance of first fruit symptoms in the orchard; (ii) inoculating detached and attached fruit in the laboratory and orchard, respectively, at various time intervals after petal fall; and (iii) starting fungicide applications at various time intervals after petal fall. Fruit of Pink Lady acquired susceptibility to the disease at about 115 days after petal fall (DAPF) when reaching a diameter of ≥55 mm. Based on these findings, a new spray strategy was adopted involving a limited number of 4 to 6 foliar sprays of azoxystrobin + difenoconazole or tebuconazole + captan, or their alternation, starting at 115 DAPF. This strategy provided excellent control of both body rot and calyx rot in Pink Lady apple fruit in Israel.
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Reuveni, M., D. Sheglov, and Y. Cohen. "Control of Moldy-Core Decay in Apple Fruits by β-Aminobutyric Acids and Potassium Phosphites." Plant Disease 87, no. 8 (August 2003): 933–36. http://dx.doi.org/10.1094/pdis.2003.87.8.933.
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Alternaria alternata is the predominant fungal pathogen responsible for moldy-core decay in the ‘Red Delicious’ apple fruits. The failure of registered fungicides to control the disease necessitated the search for alternative methods. Here we report that DL-β-aminobutyric acids (BABA) and potassium phosphite are capable of controlling moldy-core in apple fruits in the laboratory and the field. Laboratory tests involving inoculation of wounded mature fruits revealed that decay by A. alternata was 40 to 58% inhibited by 50 μg/ml and completely inhibited by 500 μg/ml of potassium phosphite. DL-BABA, R-BABA, and S-BABA at a concentration of 500 μg/ml inhibited decay formation by 82 to 90%. Potassium phosphite, BABA, and S-BABA inhibited decay formation even when applied 6 to 48 h postinoculation. In vitro tests indicated that BABA compounds did not affect conidial germination or mycelial growth, whereas potassium phosphite partially inhibited both developmental stages of the fungus. Results suggest that BABA inhibits fruit decay development indirectly, probably by inducing resistance in the host tissue, whereas potassium phosphite may act directly against the fungus. A preliminary field trial in a commercial apple orchard showed that three foliar applications of BABA or potassium phosphite, starting from the beginning of bloom until petal fall, reduced the number of fruits infected with moldy-core by 40 and 60%, respectively, relative to fruits from nontreated control trees. Results suggest that potassium phosphite and BABA could provide adequate control of moldy-core disease in apple.
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Sutton, Donald K., William E. MacHardy, and William G. Lord. "Effects of Shredding or Treating Apple Leaf Litter with Urea on Ascospore Dose of Venturia inaequalis and Disease Buildup." Plant Disease 84, no. 12 (December 2000): 1319–26. http://dx.doi.org/10.1094/pdis.2000.84.12.1319.
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Ascospores produced on diseased leaves in the leaf litter constitute the primary inoculum causing scab in commercial apple orchards in the northeastern United States. Two sanitation practices, shredding the leaf litter with a flail mower and urea application, were evaluated for their potential to reduce the risk of primary scab. Three measures of a treatment's potential were made: leaf litter density was evaluated to determine reduction of the source or primary inoculum; trapped ascospores were counted to measure the reduction of primary inoculum; and scab lesions on trees and seedlings were counted to determine reduction in disease incidence and severity on leaves and fruit. The results show that in the northeastern United States, shredding the leaf litter in November or April will reduce the risk of scab by 80 to 90% if all of the leaf litter is shredded. If 10 to 35% of the leaf litter cannot be shredded because of the limited offset of the flail mower and spread of the tree canopy, then the risk of scab is reduced by 50 to 65%. Urea applied to the leaf litter in November (when approximately 95% of the leaves had fallen) reduced the number of ascospores trapped by 50%. Urea applied to the leaf litter in April (before bud break) reduced the number of ascospores trapped by 66%. The reductions are discussed in relation to a sanitation action threshold that links sanitation to a strategy that reduces the fungicide dose to control primary scab in an orchard assessed with a moderate amount of foliar scab the previous autumn.
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Yoder, Keith S. "Effect of Powdery Mildew on Apple Yield and Economic Benefits of Its Management in Virginia." Plant Disease 84, no. 11 (November 2000): 1171–76. http://dx.doi.org/10.1094/pdis.2000.84.11.1171.
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Plots were established in a ‘Ginger Gold’ apple orchard to test the effects of different powdery mildew levels on cumulative yields. Disease pressure was heaviest in 1997 but yield effects were detected each year. Primary infection in 1997 and 1998 was correlated to previous foliar mildew incidence. Five myclobutanil applications followed by three of triadimefon (M5-T3) reduced primary infections in 1997 to 19% of those on trees not receiving a mildewcide (Ck). M5-T3 gave the most reduction in mildew incidence and severity but a schedule with two less applications (M3-T3) than M5-T3 gave the highest yield. Yields were lowest on trees not receiving a mildewcide. In 1998, the weakest and the strongest treatments had two and four times more flower clusters per tree, respectively, than Ck trees. Yield of the weakest mildew treatment (six applications of sulfur, S6), was about twice that of the Ck trees; several treatments yielded more than 2× S6. Increasing the number of sulfur applications from six to eight increased mildew control and yield. Most of the treatments resulted in yields higher than the nontreated control over a 3-year period. The M3-T3 treatment regime resulted in the highest 3-year yield, whereas a slightly more effective M5-T3 regime yielded slightly less. An economic analysis of cumulative treatment benefits, using local price inputs, is included.
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Percival, G. C. "Paclobutrazol Soil Drenches Provide Partial Reductions in Symptoms of Apple Scab of Ornamental Trees and Guignardia Leaf Blotch of Horse Chestnut." Journal of Environmental Horticulture 26, no. 2 (June 1, 2008): 87–92. http://dx.doi.org/10.24266/0738-2898-26.2.87.
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Abstract A three year field trial was conducted using established apple (Malus cv. Crown Gold) and horse chestnut (Aesculus hippocastanum L.) to assess the efficacy of paclobutrazol (PBZ) root drenches against the foliar pathogens apple scab (Venturia inaequalis (Cooke) G. Wint.,) and Guignardia leaf blotch (Guignardia aesculi (Peck) VB Stewart). In the case of horse chestnut, pathogen severity of Guignardia leaf blotch was less (23–79%) in each of the three-year experimental periods in PBZ-treated trees compared to non-treated controls. Pathogen severity of apple scab was not affected during the first year after PBZ application; however, less (25–73%) disease severity was recorded in years 2 and 3 compared to non-PBZ treated controls. An increased PBZ concentration was associated with lower pathogen severity of both fungal pathogens. Irrespective of species, less pathogen severity in PBZ-treated trees was accompanied with greater leaf chlorophyll fluorescence (16–49%) values as measures of leaf photosynthetic efficiency. Marked differences in growth regulation between apple cv. Crown Gold (tolerant) and horse chestnut (sensitive) were recorded. PBZ applications resulted in less mean stem extension in both tree species but only reduced mean leaf size of horse chestnut. Based on the results of this investigation it is suggested that PBZ root drenches potentially offer a means of reducing the severity of apple scab and Guignardia leaf blotch for professionals involved with the nursery industry. However, where a zero pathogen control policy is required supplementary fungicide sprays would be needed. Similarly, the potential loss of aesthetics due to excessive growth regulation needs to be weighed against the benefits of pathogen protection and failure of PBZ to achieve total pathogen control may result in strong selection pressure for PBZ resistance in surviving populations.
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Dang, J. L., M. L. Gleason, C. K. Niu, X. Liu, Y. Z. Guo, R. Zhang, and G. Y. Sun. "Effects of Fungicides and Spray Application Interval on Controlling Marssonina Blotch of Apple in the Loess Plateau Region of China." Plant Disease 101, no. 4 (April 2017): 568–75. http://dx.doi.org/10.1094/pdis-04-16-0464-re.
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Marssonina blotch, caused by the fungus Marssonina coronariae, is a serious foliar disease on apple in East Asia as well as in other moist temperate regions in Asia, Europe, and South America. Several fungicides were investigated for their toxicity to mycelial growth and conidial germination of the pathogen in vitro. Tebuconazole, kresoxim-methyl, hexaconazole, propiconazole, and a mixture of tebuconazole and benziothiazolinone sharply inhibited mycelial growth but had less effect on conidial germination. Field tests were conducted in a commercial orchard in Baishui County, Shaanxi Province, China, during 2012, 2013, 2014, and 2015 in order to develop recommendations for apple growers. Three applications of tebuconazole, hexaconazole, propiconazole, or a mixture of tebuconazole and benziothiazolinone at 20-day intervals from early July to late August resulted in defoliation incidence of <5%. When sprays of Bordeaux mixture + tebuconazole, Bordeaux mixture + propiconazole, and Bordeaux mixture + tebuconazole and benziothiazolinone were alternated, the spray interval was extended to 25 days and defoliation incidence remained <5%. Based on historical records and our results, scouting for symptoms should begin in mid-June. We recommend commencing the spray period in early July in years with normal rainfall patterns, and spraying in mid- to late June in years with much rainfall. The findings of this study create a foundation for implementation of an efficient spray program against Marssonina leaf blotch in apple orchards in the Loess Plateau Region of China.
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Biggs, Alan R., Henry W. Hogmire, and Alan R. Collins. "Assessment of an Alternative IPM Program for the Production of Apples for Processing." Plant Disease 84, no. 10 (October 2000): 1140–46. http://dx.doi.org/10.1094/pdis.2000.84.10.1140.
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Conventional and alternative integrated pest management (IPM) programs for managing arthropods and diseases affecting processing apple production were compared over 4 years. The effects of the two programs on populations of pest and beneficial insects, and on disease incidence and severity, were evaluated in the field and laboratory and at a commercial fruit processing plant by federal inspectors. The economic implications of the alternative management program were assessed by examining its relative costs and benefits compared with conventional management. In the alternative program, arthropods were managed with oil and Bacillus thuringiensis (Bt), and early-season diseases were managed with fungicides. Calcium chloride was used to suppress rot diseases. The alternative plots showed lower levels of indirect pests (aphids, leaf-hoppers, and mites) and increased numbers of arthropod natural enemies. On harvested fruit, there was significantly more injury in the alternative plots from codling moth or oriental fruit moth, plum curculio, and apple maggot. Levels of foliar diseases were similar between treatments; however, fruit from the alternative program exhibited significantly more sooty blotch, flyspeck, and rots. At the commercial processor, levels of cull fruit were higher for the alternative program in 2 of the 3 years with harvestable yield. Loads of fruit that were not acceptable for processing were due mostly to internal worms and worm damage. Incidence of decay was within the quality limits set by the processor, except for one conventional sample, in which decay exceeded 5%. Of the 36 loads of fruit that were examined from each program, 4 and 13 loads were rejected from the conventional and alternative programs, respectively. Net present value comparisons were dependent upon how rejected loads were valued. At cider prices for rejected loads, net returns were similar between programs. When rejected loads were valued at a complete loss, conventional net present value was over 140% higher than the alternative program. Among cultivars, Golden Delicious was most profitable and York was least profitable.
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Lee, Dong-Hyuk, Lae-Hong Cho, Jung-Sup Shin, and Jae-Youl Uhm. "Suppressive Activities of Foliar Spray Fungicides for Apple Against Sporulation of Botryosphaeria dothidea, the Causal Fungus of White Rot, and Their Role in Disease Control." Research in Plant Disease 12, no. 3 (December 1, 2006): 240–48. http://dx.doi.org/10.5423/rpd.2006.12.3.240.
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Chen, Liming, Heping Zhu, Leona Horst, Matthew Wallhead, Michael Reding, and Amy Fulcher. "Management of Pest Insects and Plant Diseases in Fruit and Nursery Production with Laser-guided Variable-rate Sprayers." HortScience 56, no. 1 (January 2021): 94–100. http://dx.doi.org/10.21273/hortsci15491-20.
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Laser-guided variable-rate intelligent spray technology is anticipated to reduce pesticide use in production of crops and safeguard the environment. However, the ability of this technology to effectively control insect pests and diseases of crops must be validated before it becomes part of integrated pest management programs. Abilities of three different intelligent sprayers were tested to control pest insects and plant diseases at one fruit farm and two ornamental nurseries in Ohio during three consecutive growing seasons. The same sprayers with disabled intelligent functions were used as conventional constant-rate applications for comparisons. Test crops were apple (Malus pumila), peach (Prunus persica), blueberry (Vaccinium sect. Cyanococcus), black raspberry (Rubus occidentalis), crabapple (Malus sp.), maple (Acer sp.), birch (Betula sp.), and dogwood (Cornus florida). There were five insects and six diseases total involved in the investigations in the fruit farm and two nurseries. The field tests showed the intelligent spray applications reduced pesticide and foliar fertilizer use by ≈30% to 65% on average during the 3-year experiments. At the same time, intelligent spray technology was similar or more effective than conventional spray technology when controlling insects and diseases on a variety of crops. These results demonstrated that intelligent spray technology was environmentally friendly and more effective for control of insect and disease pests in fruit farms and ornamental tree nurseries.
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Hoque, MZ, AM Akanda, MIH Mian, and MKA Bhuiyan. "Efficacy of fungicides and organic oils to control powdery mildew disease of jujube (Ziziphus mauritiana Lam.)." Bangladesh Journal of Agricultural Research 38, no. 4 (June 1, 2014): 659–72. http://dx.doi.org/10.3329/bjar.v38i4.19032.
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Powdery mildew (Oidium erysiphoides f.sp. ziziphi) is the major disease of Indian jujube (Ziziphus mauritiana) in Bangladesh. An experiment was conducted to test the efficacy of six fungicides, two organic oils, and a detergent against the disease. Tested fungicides were Tilt (Propiconazole) @ 0.05%, Folicur (Hexaconazole) @ 0.1%, Bavistin DF (Carbandazim) @ 0.2%, Dithane M-45 (Mancozeb) @ 0.3%, Thiovit 80 WG (Sulpher) @ 0.3%, and Cupravit (Copper) @ 0.3%, the oils were Mustard oil @ 0.5% and Neem oil 0.5%, and the Detergent (Trix) @ 0.5%. The materials were applied as foliar spray for seven times at an interval of 15 days. All of the fungicides and two oils gave significant decrease in severity of powdery mildew and increased fruit yield of Indian jujube irrespective of varieties, locations and over times. Among the treatments, Folicur, Tilt, Thiovit, and Dithane M-45 sprays were found effective than others. The severity index values on two jujube varieties were 3.89-4.50 at Mowna and 4.00-4.53 at Ishurdi in control treatment. The severity indices were reduced to 1.45-1.96 at Mowna and 1.33-2.07 at Ishurdi due to application of Tilt, Folicur, Thiovit, and Dithane M-45, which gave increase in fruit yield over control by 68.88, 63.69, 63.04, and 54.63% in Apple Kul and 83.25, 77.87, 77.39, and 70.36% in BAU Kul, respectively. Most of the treatments were able to reduce number of spotted fruits. The best effective fungicide was found to be Tilt followed by Folicur and Thiovit in reducing disease severity of powdery mildew as well as other fruit diseases like fruit spot and fruit rot and increase fruit yield of Indian jujube. Therefore, Tilt/Folicur may be recommended for jujube growers to control the powdery mildew disease in commercial orchard. DOI: http://dx.doi.org/10.3329/bjar.v38i4.19032 Bangladesh J. Agril. Res. 38(4): 659-672, December 2013
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Uchida, J. Y., and L. L. Loope. "A Recurrent Epiphytotic of Guava Rust on Rose Apple, Syzygium jambos, in Hawaii." Plant Disease 93, no. 4 (April 2009): 429. http://dx.doi.org/10.1094/pdis-93-4-0429b.
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A Neotropical rust of the Myrtaceae, Puccinia psidii Winter, was described from Psidium guajava L., or guava, in Brazil in 1884 (1). It was first discovered in Hawaii on potted Metrosideros polymorpha Gaud. on Oahu in April 2005 (2) with pathogenicity and identity established (3). It spread quickly, and by January 2006, severe outbreaks of this rust occurred statewide on new leaves of Syzygium jambos (L.) Alston, or rose apple. Rose apple, a native to South and Southeast Asia, was introduced to Hawaii in 1825 and is locally abundant to invasive from just above sea level to as high as 1,000 m in elevation in wet sites. Healthy, reddish green immature leaves on new twigs become deformed, yellow-red, and covered with masses of yellow urediniospores following infection. As the disease progresses, infected leaves are blackened and defoliate, with no functional leaves formed. Stem tips and branches are killed and the canopy becomes progressively smaller. Repeated mortality of juvenile leaves was observed to kill 8 to12 m tall trees in the Haiku area of Maui. Wind dispersal of urediniospores resulted in heavy infection of even small groups of S. jambos isolated by 1 km or more and billions of urediniospores covered the ground under diseased trees. On Hawaii, Maui, and Oahu, trees with many dead branches are becoming common with concerns about the fire hazard of these dead trees surrounded by dry grasses. At low humidity levels, or on more mature leaves characterized by soft expanded yellow-green tissue, fewer, mostly circular spots are formed that do not expand. S. jambos is an example of a highly vulnerable host in Hawaii and represents one of approximately 3,500 species of Myrtaceae outside the Neotropics growing in Australasia, Southeast Asia, the Pacific, and tropical Africa, which have evolved unexposed to P. psidii. Severely infected S. jambos plants have been the major source of spores in the environment, exposing many Myrtaceae hosts to P. psidii. The pathogenicity of P. psidii has been consistent among and within islands with S. jambos severely infected and M. polymorpha, Melaleuca quinquenervia, Rhodomyrtus tomentosa, Myrtus communis, and Eugenia species commonly infected. Other hosts such as S. cumini, S. malaccense, and Myriciaria cauliflora are also infected, although guava and Eucalyptus spp. are rarely infected. Strain differences within P. psidii are suspected (4). In the tropics, it is rare for mature trees to be killed by a foliar pathogen, but given the devastation of new growth, death of more S. jambos trees is likely. References: (1) T. A. Coutinho et al. Plant Dis. 82:819, 1998. (2) E. M. Killgore and R. A. Heu. New Pest Advisory No. 05-04. Hawaii Department of Agriculture, 2007. (3) J. Y. Uchida et al. Plant Dis. 90:524, 2006. (4) S. Zhong et al. Mol. Ecol. Res. 8:348. 2008.
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Elliott, M., G. A. Chastagner, K. P. Coats, P. Sikdar, and C. L. Xiao. "First Report of a New Leaf Blight Caused by Phacidiopycnis washingtonensis on Pacific Madrone in Western Washington and Oregon." Plant Disease 98, no. 12 (December 2014): 1741. http://dx.doi.org/10.1094/pdis-05-14-0462-pdn.
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In recent years, a leaf blight disease, consisting of browned, desiccated leaves occurring mainly in the lower parts of the canopy, has been observed during wet springs on Pacific madrone (Arbutus menziesii) in western Washington and Oregon. In May 2009 and 2011, severe outbreaks occurred and symptomatic leaves from madrones growing in the region were sampled to determine the causal agent. Two symptoms, leaf necrosis or blotching along the edges and tips of the leaves, and leaf spot, were observed. Small segments of diseased tissue were cut from the leaves, surface-disinfected, rinsed, and plated on malt extract agar. Fifty percent of the leaf blotch and 30% of leaf spot samples yielded a fungus that was fast-growing (20 mm diameter in 4 days at 25°C) and produced colonies that were a pale gray with dark gray reverse and a felty texture. On potato dextrose agar (PDA), pycnidia formed and exuded conidia in peach-colored droplets after 2 weeks under room temperature and light conditions. Pycnidia were spherical and 12.5 to 39.8 μm, average 24.2 μm in diameter. Conidia were hyaline, ovoid, and 5.8 to 8.5 × 3.1 to 4.7 μm (average 7.0 × 3.7 μm). The fungus was identified as Phacidiopycnis washingtonensis based on its morphology (1). To confirm the identity, the internal transcribed spacer (ITS) region of the rDNA was amplified with ITS1/ITS4 primers (2) and sequenced (GenBank Accession Nos. JQ743784 to 86). BLAST analysis showed 100% nucleotide identity with those of P. washingtonensis in GenBank (AY608648). The fungus was also isolated from lesions on green shoots and the petiole and leaf blade of dead attached leaves. To test pathogenicity, 3-year-old Pacific madrone seedlings (three for each isolate) were inoculated with five isolates of the fungus and maintained in the greenhouse (25°C); the experiment was conducted twice. Five leaves from each tree were cold injured (–50°C) at a marked 5 × 5 mm2 area with a commercial aerosol tissue freezing product prior to inoculation and five leaves were not cold injured. A 5-mm-diameter mycelial plug cut from the margin of 6-day-old PDA culture was applied to the marked areas on the upper leaf surface. The inoculated area was covered with moist cheese cloth and wrapped with Parafilm. Leaves treated with blank PDA plugs served as control. Leaves were enclosed in plastic bags to maintain moisture for the first 15 h post inoculation and cheese cloths were removed after 15 days. All cold-injured inoculated leaves showed symptoms of blight starting at 2 weeks after inoculation, and no symptoms appeared on the controls. On non-cold injured inoculated leaves, only one isolate caused symptoms (80% of all leaves). The fungus was re-isolated from diseased leaves. These results suggest that P. washingtonensis is able to cause foliar blight on Pacific madrone when leaves are subjected to cold stress. Increased disease severity on madrone observed in spring 2011 in Washington and Oregon may have been due to predisposition of foliage to extreme cold in November 2010 and February 2011. This fungus has previously been reported to cause a postharvest fruit rot disease on apple fruit and a canker and twig dieback disease of apple and crabapple trees in WA (1). To our knowledge, this is the first report of P. washingtonensis causing a leaf blight disease on Pacific madrone in North America. References: (1) C. L. Xiao et al. Mycologia 97:464, 2005. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.
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Vieira de Cisne, Carolinna, Aline Cristina Velho, Mathias Ferrari Rockenbach, and Marciel João Stadnik. "Variação morfo-cultural e agressividade de Colletotrichum fructicola em um pomar de macieira em Fraiburgo-SC." Agropecuária Catarinense 30, no. 1 (May 3, 2017): 66–72. http://dx.doi.org/10.52945/rac.v30i1.12.
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Resumo – A maçã é uma das frutas de clima temperado de maior importância para a economia do Sul do Brasil. Nessa região, as plantas são severamente afetadas pela mancha foliar de Glomerella (MFG), uma doença causada por espécies de Colletotrichum. O objetivo do presente trabalho foi identificar as espécies predominantes de isolados causadores de MFG provenientes de um mesmo pomar localizado em Fraiburgo, SC e verificar se dentro dessa população existia variação nos níveis de agressividade. A identificação molecular dos isolados foi realizada mediante sequenciamento e análise da homologia das regiões ITS, TUB2, GAPDH e HIS3. Para a caracterização morfo-cultural, os isolados foram cultivados em meio BDA a 25ºC e 12h de fotoperíodo durante 10 dias. Para avaliação da agressividade, plântulas suscetíveis (cv. Gala) foram inoculadas com uma suspensão contendo 1x106 conídios/ml. Todos os isolados foram identificados como Colletotrichum fructicola. Cerca de 50% dos isolados apresentaram micélio ralo com coloração de branco-oliva na frente e salmão no verso. Seis isolados formaram peritécios. Os conídios foram predominantemente cilíndricos com largura e comprimento médio de 4,2-4,5µm e 12,1-13,4µm, respectivamente. Os isolados foram classificados em três níveis de agressividade, sendo que o mais agressivo causou 80% de necrose em folhas. As implicações desses achados para o controle da MFG são discutidas.Abstract – Apple is one of the most important temperate fruit for the Southern Brazil’s economy. In this region, the production is severely affected by Glomerella leaf spot (GLS), caused by Colletotrichum spp. The objective of this study was to identify the predominant species causing GLS in an apple orchard in Fraiburgo, SC and to assess whether there were isolates with different levels of aggressiveness in the population. The molecular identification was carried out by sequencing and analysis of the homology regions ITS, TUB2, GAPDH and HIS3. For morphological and cultural characterization, the isolates were cultured on PDA at 25°C and 12h of photoperiod during 10 days. Susceptible seedlings (cv. Gala) were inoculated with a solution containing 1x106 conidia/ml for aggressiveness assessing. All isolates were identified as Colletotrichum fructicola. Fifty percent of isolates exhibited mycelium thin with white-olive coloration and a salmon reverse. Six isolates formed perithecia. Conidia were predominantly cylindrical with width and length ranged from 4.2 to 4.5µm and 12.1 to 13.4µm, respectively. The isolates were classified into three aggressiveness levels, and one of them was highly aggressive with 80% of necrotic leaf area. Implications of these findings for disease control are discussed.
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Holguín-Peña, R. J., R. Vázquez-Juárez, and R. F. Rivera-Bustamante. "A New Begomovirus Causes Tomato Leaf Curl Disease in Baja California Sur, Mexico." Plant Disease 89, no. 3 (March 2005): 341. http://dx.doi.org/10.1094/pd-89-0341a.
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More than 10,000 ha of tomatoes are grown in the field and greenhouses on the Baja California Peninsula of Mexico. Information about the etiology of geminivirus-like diseases affecting tomato crops in all horticultural regions in the area has been difficult to obtain and assess. From 2001 through 2003, stunting, foliar discoloration, reduced leaf size, and leaf crumpling symptoms were observed and analyzed in one large area of tomato plantings in El Carrizal (near the city of La Paz in Baja California Sur). This leaf curl disease resembled that caused by Chino del tomate virus and has been observed at levels of incidence ranging from 60 to 90%. DNA isolated from symptomatic plants was analyzed using DNA hybridizaton and polymerase chain reaction (PCR) amplification of the 5′ regions of the replication and coat protein genes, including the intergenic region (3). Comparisons of the nucleotide sequence (GenBank Accession No. AY339619) with corresponding sequences in GenBank resulted in 84.2% identity with Tomato mild mottle virus and 61.7% with Tomato severe leaf curl virus; both isolates originate from Central America. The relatively low nucleotide sequence identities from its closest relatives suggested that the virus may be a new begomovirus species of unambiguous American ancestry. In a phylogenetic analysis using PAUP 4.0 software, the Baja California isolate clustered in a separate group from other Mexican sequences. Moreover, the iteron (iterative sequences motifs associated in virus replication) arrangements (1) are unique among known New World begomoviruses, but identical to analogous elements from a tobacco-infecting begomovirus from China. On the other hand, it is well known that there are interactions between geminiviruses in mixed infections in some horticultural areas of Mexico (2). To determine the identity of the putative geminivirus involved in the disease, we used selected restriction enzyme (EcoRI, HindIII and XbaI) analysis and PCR with specific primers. No evidence of mixed infections with other geminiviruses was obtained. DNA fragments of the expected size (1.1 kb) showed different digestion patterns compared with other well-characterized geminiviruses isolated from Mexico such as Chino del tomate virus, Pepper huasteco yellow vein virus, Tomato leaf curl Sinaloa virus, and Pepper golden mosaic virus. Epidemiological, experimental, and natural host range studies indicated that the Baja California isolate has a relatively narrow host range infecting tomatoes, peppers (Capsicum annuum L.), and Peruvian apple (Nicandra physalodes L.). Reproduction of characteristic leaf curling symptoms in tomato seedlings infected with viruliferous whiteflies (Bemisia tabaci Genn.) and inoculated biolistically using infectious DNA (0.5 μg/ml) as inoculum were obtained. Koch's postulates were completed using PCR and DNA hybridization to confirm virus identity. These results confirm that the Baja California isolate is different from other begomoviruses isolated from Mexico. The virus is tentatively named Tomato chino Baja California virus (ToChBCV), genus Begomovirus, family Geminiviridae. References: (1) G. R. Arguello-Astorga et al. Arch. Virol. 146:1465, 2001. (2) J. Mendez-Lozano et al. Phytopathology 93:270, 2003. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993.
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Percival, Glynn, and Ian Haynes. "The Influence of Calcium Sprays to Reduce Fungicide Inputs Against Apple Scab [Venturia inaequalis (Cooke) G. Wint.]." Arboriculture & Urban Forestry 35, no. 5 (September 1, 2009): 263–70. http://dx.doi.org/10.48044/jauf.2009.040.
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A goal of pathogen management in the arboriculture industry should be to eliminate or reduce the amount of active ingredients of synthetic fungicides used within a growing season. The aim of this research paper was to evaluate a nonfungicidal pathogen management system by investigating the hypothesis that replacing an apple scab fungicide spray program with calcium reduces fruit and leaf scab severity. In addition, a separate study investigated if a relationship existed between calcium concentrations within foliar tissue of resistant, intermediate, and sensitive apple species and varieties toward scab infection. A number of commercially available calcium products were applied to apple cv. Crown Gold trees at four distinct growth stages (bud break, 90% petal fall, early fruitlet, two weeks after early fruitlet). A comparative evaluation of the synthetic fungicide penconazole commercially used for scab control was also conducted. The experiment was performed in 2006 and repeated in 2007 at the University of Reading Experimental Field Site (UK). Application of calcium sprays significantly reduced the leaf and fruit scab severity of apple cv. Crown Gold however; in a separate study no relationship existed between foliar calcium content and susceptibility to apple scab attack between resistant, intermediate, and sensitive Malus species. Greatest protection in both field trials was provided by the synthetic fungicide penconazole. Within the calcium products evaluated, greatest protection in both field trials was provided by calcium chloride and calcium hydroxide. The integration of calcium foliar sprays into existing scab management practices offers a useful addition to reduce scab severity on ornamental apples that has applicability against other foliar diseases frequently encountered within urban landscapes.
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Bockus, W. W., R. L. Bowden, M. M. Claassen, W. B. Gordon, W. F. Heer, and J. P. Shroyer. "Time of application and winter wheat genotype affect production of large seed after fungicide application." Canadian Journal of Plant Science 77, no. 4 (October 1, 1997): 567–72. http://dx.doi.org/10.4141/p97-038.
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Two field experiments were established to compare four times of fungicide application (flag leaf emergence, boot, fully headed, and milky ripe) for improving production of large seed. Quadratic models fit the data when large-seed (≥0.238-cm diameter) yields were regressed against time of fungicide application. The optimum time to apply foliar fungicides was between boot and fully headed. Four other field experiments were established to compare large-seed yields after fungicide application on 12 cultivars differing in susceptibility to foliar diseases. With moderate foliar disease pressure, linear models fit the data when increases in large seed due to fungicide were regressed against Kansas Cooperative Extension Service disease ratings. In conjunction with the expected price of seed wheat, these models can be used to help decide whether foliar fungicide is warranted. Key words: Pyrenophora tritici-repentis, Puccinia recondita, Septoria tritici, Stagonospora nodorum, seed cleanout, tebuconazole, propiconazole, foliar disease control
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Poleatewich, Anissa M., Henry K. Ngugi, and Paul A. Backman. "Assessment of Application Timing of Bacillus spp. to Suppress Pre- and Postharvest Diseases of Apple." Plant Disease 96, no. 2 (February 2012): 211–20. http://dx.doi.org/10.1094/pdis-05-11-0383.
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Four isolates of Bacillus spp. were tested in a 2-year field study for biological control of pre- and postharvest diseases of apple. For the preharvest test, bacteria were applied to ‘Golden Delicious’ and ‘Rome Beauty’ trees in May or May and June. Foliar apple scab severity was assessed weekly. After harvest, fruit were wounded and then either left untreated or given a postharvest application of the bacteria. Wounded fruit were then inoculated with the bitter rot pathogen and lesion size was measured over 8 days. Bacillus megaterium isolate A3-6, B. mycoides isolate A1-1, and B. cereus isolate FLS-5 applied in May or May and June significantly reduced fruit and foliar apple scab severity in both years. A postharvest application of the bacteria (alone or in combination with a preharvest application) resulted in the greatest suppression of bitter rot on both cultivars (P < 0.04). The May + June + postharvest application of isolate A3-6 resulted in the greatest suppression of bitter rot, with an average of 45 and 95% reduction in lesion size compared with nontreated controls on ‘Golden Delicious’ and ‘Rome Beauty’ fruit, respectively. Results from this study indicate that preharvest applications of the bacteria were able to reduce foliar and fruit scab and an additional postharvest application was effective in reducing bitter rot severity.
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Biggs, Alan R., George W. Sundin, David A. Rosenberger, Keith S. Yoder, and Turner B. Sutton. "Relative Susceptibility of Selected Apple Cultivars to Apple Scab Caused by Venturia inaequalis." Plant Health Progress 11, no. 1 (January 2010): 20. http://dx.doi.org/10.1094/php-2010-0408-01-rs.
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Apple scab is the most important disease of apples (Malus domestica) in the cool temperate regions where apples are grown. Data were collected over several years from plantings of new apple cultivars and selections established at multiple locations in 1995 (23 entries) and 1999 (24 entries) as part of regional project NE-183. Golden Delicious and McIntosh were the standards in both plantings. Data on incidence of scab on leaves and fruit were collected and analyzed to determine differences due to location and cultivar. None of the analyses indicated significant cultivar differences due to location, likely confirming the diversity of the apple scab fungus in the eastern United States. In general, for scab on leaves, the cultivars Ginger Gold, Orin, Cripps Pink, Silken, and Delblush were as susceptible as McIntosh, a common standard for scab susceptibility in the eastern United States. For scab on fruit, the cultivars Fuji, Cameo, Cripps Pink, Ambrosia, and Silken, and the selection NJ 90, were as susceptible as McIntosh. As expected, the cultivars and selections with genetic resistance to the scab pathogen exhibited the lowest incidences of apple scab on foliage and fruit. Gala Supreme, Sansa, and Honeycrisp, while susceptible to scab, exhibited relatively low levels of the disease. Accepted for publication 2 February 2010. Published 8 April 2010.
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Bhat, Mushtaq Ahmad, Z. A. Bhat, G. H. Mir, S. Banday, and Tariq Ahmad. "Kresoxim methyl SC-a Quinone Outside Inhibitor against Major Fungal Foliar Diseases of Apple." Pesticide Research Journal 33, no. 2 (2021): 65–74. http://dx.doi.org/10.5958/2249-524x.2021.00040.6.
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Telenko, Darcy E. P., Jeffrey D. Ravellette, and Kiersten A. Wise. "Assessing Late Vegetative and Tasseling Fungicide Application Timings on Foliar Disease and Yield in Indiana Corn." Plant Health Progress 21, no. 4 (January 1, 2020): 224–29. http://dx.doi.org/10.1094/php-03-20-0022-rs.
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Gray leaf spot (Cercospora zeae-maydis) is a foliar disease of corn (Zea mays) that consistently reduces yields across the United States and is an annual concern in Indiana corn production. Field trials were conducted in West Lafayette, IN, over 3 years (2016 to 2018) to evaluate the effectiveness of 12-leaf collar stage (V12) foliar fungicide applications compared with tasseling (VT) applications for gray leaf spot management and yield. Results indicated that during years in which foliar disease severity was less than 4%, there was no effect of application timing on gray leaf spot severity. In 2018, when gray leaf spot levels exceeded 5%, significantly less disease was observed in treatments receiving VT applications compared with V12 applications. Application timing did not affect yield in any year of the experiment. In 2016, benzovindiflupyr + azoxystrobin + propiconazole resulted in greater yields compared with the nontreated control, and in 2018, pyraclostrobin + metconazole and benzovindiflupyr + azoxystrobin + propiconazole resulted in greater yields compared with the nontreated control. This research indicates that in high disease pressure environments and years, Indiana farmers may want to continue to apply fungicides at VT rather than apply prior to tassel.
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Percival, Glynn, and Sean Graham. "Calcium and Silicon Fertiliser Influence on Fungicide Efficacy Against Guignardia Leaf Blotch and Apple Scab Management." Arboriculture & Urban Forestry 47, no. 4 (July 1, 2021): 170–81. http://dx.doi.org/10.48044/jauf.2021.016.
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Management of fungal diseases within urban landscapes relies heavily on repeat fungicide sprays. Environmental concerns have led to a need to eliminate or reduce fungicide use. Foliar sprays of calcium- (Ca) and silicon- (Si) based fertilisers have been shown to reduce symptom severity of several fungal pathogens. The aim of our research was to evaluate the influence of Ca chloride, Ca metasolate, tetra ethyl silicate, and potassium silicate fertilisers, applied independently and in combination with a synthetic fungicide (penconazole) at full and half strength, on apple scab (Venturia inaequalis) and Guignardia leaf blotch (Guignardia aesculi) symptom severity, as well as leaf chlorophyll content, fruit yield, and crown volume. Trials used container-grown Aesculus hippocastanum and field-grown Malus domestica cv. ‘Golden Delicious’. Applications of Ca, Si, and penconazole sprays alone significantly reduced scab and leaf blotch severity compared to water-sprayed controls; however, a significant difference between the type of Ca and Si fertilisers was recorded. A combined mix of a Ca or Si fertiliser with a full or half dose of penconazole was more effective at reducing symptom severity of both foliar pathogens than a full or half dose of penconazole alone. Data analysed with Limpel’s formula indicated positive synergistic effects between Ca and Si and penconazole in some, but not all, cases. The integration of Ca and Si foliar sprays as an alternative to, or additive with, penconazole for scab and leaf blotch management appears feasible based on results of our studies and may have applicability against other fungal pathogens.
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Papp-Rupar, Matevz, Leone Olivieri, Robert Saville, Thomas Passey, Jennifer Kingsnorth, Georgina Fagg, Hamish McLean, and Xiangming Xu. "From Endophyte Community Analysis to Field Application: Control of Apple Canker (Neonectria ditissima) with Epicoccum nigrum B14-1." Agriculture 13, no. 4 (March 31, 2023): 809. http://dx.doi.org/10.3390/agriculture13040809.
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Apple canker, caused by Neonectria ditissima (Tul. and C. Tul.) Samuels and Rossman, is a major disease of apples (Malus domestica) worldwide. N. ditissima infects through natural and artificial wounds. Infected wood develops canker lesions which girdle branches and main stems causing reduced yield and tree death. N. ditissima is difficult to control; removal of inoculum (cankers) is expensive and therefore seldom practiced, whilst effective chemical products are being banned and no biocontrol products have been found to be effective against N. ditissima. This study used cues from a previous apple endophyte community analysis to isolate and test fungal endophytes belonging to the genus Epicoccum as potential endophytic biocontrol agents. Epicoccum nigrum B14-1, isolated from healthy apple trees, antagonised N. ditissima in vitro and reduced the incidence of N. ditissima infections of leaf scars by 46.6% and pruning wounds by 5.3% in field conditions at leaf fall. Autumn application of B14-1 conidia increased E. nigrum abundance in apple tissues at 10–20 days post-inoculation by ca. 1.5×, but this returned to control levels after one year. E. nigrum B14-1 did not cause detrimental effects on apple foliage, buds, fruit, or growth and could therefore present a new biocontrol agent to manage N. ditissima in commercial apple production.
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Breitkreutz, Sarah, and James Flore. "Whole Plant Measurement of Photosynthesis and Development of Apple Trees in Relation to Pest Damage." HortScience 33, no. 3 (June 1998): 540e—541. http://dx.doi.org/10.21273/hortsci.33.3.540e.
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The objectives of this study were to determine the relationship of whole-plant photosynthesis (WPP) and overall growth of apple trees to the damage caused by insects and disease. This project was part of a larger experiment involving a pest control system consisting of different control strategies, with integrated pest management being one. WPP was measured seven times during the 1997 growing season on 16 single-tree replicates of apple trees from two varieties, `Empire' and `Liberty', on M-9 rootstocks at the Clarksville Horticulture Experiment Station. WPP was measured on trees subjected to six pesticide and fungicide treatments that were part of the established study. In addition to these measurements, the leaf number and area were determined at the time of the measurement. At three times during the growing season, an estimation of insect damage to the fruit and foliage were determined. At harvest, the total number, size distribution, and weight of the apples from each tree was measured. In addition, an estimation of pest and disease damage to the fruit was conducted. Results showed a decrease in the rate of WPP as the season progressed. All of the treatments had higher rates of photosynthesis than the control trees. In addition, the soft chemical treatments had higher rates of photosynthesis than the conventional IPM treatments, 1.8 and 1.5 mmol CO2/cm2 trunk cross sectional area per s, respectively. Further details of these results and the relationships between foliage damage, photosynthesis and tree yield will be presented.
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Rowan, S. J. "Triadimefon Controls Fusiform Rust in Young Slash Pine Plantations." Southern Journal of Applied Forestry 10, no. 2 (May 1, 1986): 112–14. http://dx.doi.org/10.1093/sjaf/10.2.112.
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Abstract Triadimefon (Bayleton®) effectively controlled fusiform rust in a slash pine (Pinus elliottii Engelm. var. elliottii) plantation when three or more foliar sprays containing 600 ppm a.i. were applied annually (March to June) to runoff. Fewer foliar sprays and a top-dip applied at planting did not provide effective control of the disease. From the spray volumes applied over a five-year period, an estimated maximum of 505 mg a.i. triadimefon accumulated per tree. This amount did not reduce tree growth or survival. South. J. Appl. For. 10:112-114, May 1986.
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Craze, Hamish A., Nelishia Pillay, Fourie Joubert, and Dave K. Berger. "Deep Learning Diagnostics of Gray Leaf Spot in Maize under Mixed Disease Field Conditions." Plants 11, no. 15 (July 26, 2022): 1942. http://dx.doi.org/10.3390/plants11151942.
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Maize yields worldwide are limited by foliar diseases that could be fungal, oomycete, bacterial, or viral in origin. Correct disease identification is critical for farmers to apply the correct control measures, such as fungicide sprays. Deep learning has the potential for automated disease classification from images of leaf symptoms. We aimed to develop a classifier to identify gray leaf spot (GLS) disease of maize in field images where mixed diseases were present (18,656 images after augmentation). In this study, we compare deep learning models trained on mixed disease field images with and without background subtraction. Performance was compared with models trained on PlantVillage images with single diseases and uniform backgrounds. First, we developed a modified VGG16 network referred to as “GLS_net” to perform binary classification of GLS, which achieved a 73.4% accuracy. Second, we used MaskRCNN to dynamically segment leaves from backgrounds in combination with GLS_net to identify GLS, resulting in a 72.6% accuracy. Models trained on PlantVillage images were 94.1% accurate at GLS classification with the PlantVillage testing set but performed poorly with the field image dataset (55.1% accuracy). In contrast, the GLS_net model was 78% accurate on the PlantVillage testing set. We conclude that deep learning models trained with realistic mixed disease field data obtain superior degrees of generalizability and external validity when compared to models trained using idealized datasets.
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Robertson, Alison E., Mauricio Serrano, Jyotsna Acharya, John Shriver, John Beckman, Chad Huffman, Ken Pecinovsky, et al. "Effect of Foliar Fungicides Applied at Silking on Stalk Lodging in Corn." Plant Health Progress 21, no. 1 (January 1, 2020): 2–8. http://dx.doi.org/10.1094/php-08-19-0049-rs.
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Stalk lodging in corn (Zea mays L.) leads to harvest complications and yield losses. Farmers who apply a foliar fungicide to manage leaf diseases have also observed reduced lodging. The goal of this study was to evaluate the effect of a foliar fungicide applied at silking on percent lodging. Field trials were established on Iowa State University Research Farms in 2016 and 2017. Treatments evaluated were foliar fungicide application (with or without) and harvest date (corn harvested at weekly intervals for up to 5 weeks); a split plot design was used with four complete blocks. Across all locations and years, a fungicide application significantly reduced mean lodging (P < 0.0001) by 9.3% and increased yields (P = 0.0043) by an average of 258.3 kg/ha (4.1 bu/acre). Percent lodging increased as harvest was delayed (P < 0.0001). This study demonstrated that foliar fungicides applied at silking reduced lodging and thus confirmed observations of farmers. Applying a fungicide to reduce lodging and favor harvest, however, is not recommended due to risk of fungicide resistance development and the lack of efficacy on stalk rot pathogens.
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Brennan, R. F., and K. W. Jayasena. "Increasing applications of potassium fertiliser to barley crops grown on deficient sandy soils increased grain yields while decreasing some foliar diseases." Australian Journal of Agricultural Research 58, no. 7 (2007): 680. http://dx.doi.org/10.1071/ar06286.
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Most sandy soils used for cropping in south-western Australia (SWA) have now become potassium (K) deficient due to removal of K in hay and grain, so it is now profitable to apply K fertiliser to most barley (Hordeum vulgare L.) crops in the region. Leaf diseases of barley crops in the region have increased in recent years particularly in the in medium to high (350–600 mm annual average rainfall) areas of SWA. Seventeen field experiments were undertaken to determine the effect of applications of K fertiliser, either the chloride (KCl) or sulfate source (K2SO4), on grain yield increases and on the percentage leaf area diseased (%LAD) when diseases were controlled or not controlled by fungicide sprays. Maximum grain yield of barley was achieved where adequate K fertiliser (~8–22 kg K/ha) was applied and leaf diseases were controlled by fungicide. Applying increasing amounts of applied K fertiliser (0–120 kg K/ha) to barley decreased the %LAD by powdery mildew (Blumeria graminis f. sp. hordei Syn.) and spot-type net blotch (Pyrenophora teres f. maculata (Sacc.) Shoem.) and increased grain yield. By contrast, when leaf rust (Puccinia hordei G. Otth) was present the %LAD was unaffected by K application. When powdery mildew was the major disease, larger increases in grain yields and larger reductions in %LAD were obtained when KCl was used instead of K2SO4. About twice as much K fertiliser as K2SO4 was required for 90% maximum grain yield compared with KCl where powdery mildew was present. Applying larger amounts (>40 kg K/ha) of K fertiliser than required to achieve maximum grain yields did not further reduce %LAD by powdery mildew. There were no significant differences between the 2 sources of K fertiliser on the %LAD by spot-type net blotch. Generally, the percentage protein content and hectolitre weight of grain were unaffected by K fertiliser. Potassium fertiliser decreased the percentage grain < 2.5 mm (known locally as screenings) and control of the foliar leaf diseases by applications of fungicide resulted in a decrease in protein content and screenings and increased hectolitre weight of barley grain. The concentration of K in dried shoots that was related to 90% of the maximum shoot yield (critical diagnostic K) decreased as the plant matured, and was ~41 g/kg at Z22, ~30 g/kg at Z32, ~20 g/kg at Z40, and ~15 g/kg at Z59. The concentration of K in dried shoots which was related to 90% of the grain yield (critical prognostic K) decreased as plant matured, and was similar to critical diagnostic K values. Leaf disease had little effect on critical concentrations of K at early growth stages (Z22 and Z32).
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Smirnov, Igor, Alexey Kutyrev, and Nikolay Kiktev. "Neural network for identifying apple fruits on the crown of a tree." E3S Web of Conferences 270 (2021): 01021. http://dx.doi.org/10.1051/e3sconf/202127001021.
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To identify the fruits on the crowns of trees and count their number, a software and hardware complex (PAC) based on a technical vision system and a recurrent neural network of deep learning has been developed. The created neural network and class allocation algorithms allow the software and hardware complex to function stably in the conditions of industrial horticultural plantings, regardless of the size and interference of foliage, to determine the color of the fruit surface, to identify the presence of diseases and defects of fruits. The developed package provides digital monitoring of both photographic materials and video streams in online mode.
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Makowski, D., R. Bancal, and A. Vicent. "Estimation of Leaf Wetness Duration Requirements of Foliar Fungal Pathogens with Uncertain Data—An Application to Mycosphaerella nawae." Phytopathology® 101, no. 11 (November 2011): 1346–54. http://dx.doi.org/10.1094/phyto-01-11-0024.
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Wetness of the host surface is a critical environmental factor for the development of foliar fungal diseases, but it is difficult to estimate the wetness durations required by pathogens for infection when only few experimental data are available. In this paper, we propose a method to estimate wetness duration requirements of foliar fungal pathogens when precise experimental data are not available. The proposed method is based on approximate Bayesian computation. It only requires lower and upper bounds of wetness duration requirements for one or fewer temperatures. We describe the method, show how to apply it to an infection model, and then present a case study on Mycosphaerella nawae, the causal agent of circular leaf spot of persimmon. In this example, the parameters of a simple infection model were estimated using experimental data found in the literature for the pathogen, and the model was applied to assess the risk in a Spanish area recently affected by the disease. The results showed that the probability of successful infection was higher than 0.5 for 32% of the on-site wetness durations recorded in the affected area. Results obtained with simulated data showed that our method was able to improve the estimation of wetness duration requirement. Given the flexibility of the proposed method, we expect it to become adopted for assessing the risk of introduction of exotic fungal plant pathogens.
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Naffaa, Walid Ghazi, and Abeer Rashid. "Fungal pathogens associated with crown and collar rot of apple trees in southern Syria." Acta agriculturae Slovenica 109, no. 1 (January 24, 2017): 103. http://dx.doi.org/10.14720/aas.2017.109.1.10.
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<p>Crown and collar rot of apple trees is a destructive and widespread disease in most areas of the world. Surveys have been done to describe disease symptoms, estimate the disease incidence, and identify the pathogens associated with this disease in southern Syria. Disease incidence was 0.08 – 10 % in most studied sites, only in Alroom location it was up to 14.7 % in 2014 and 17.8 % in 2015, with average of 11.8 %. Symptoms included small pale green leaves, sparse foliage, and a reddish-brown discoloration of inner bark of the infected area at the base of infected tree. The isolated fungi belonged to genera and form genera <em>Phytophthora</em>, <em>Rosellinia</em>, <em>Rhizoctonia</em>, <em>Phialophora</em>, <em>Acremonium</em>, <em>Pestalotiopsis</em>, <em>Cylindrocarpon</em> and <em>Verticillium</em>.<em> Phytophthora </em>was isolated from all infected trees, and was the most frequent pathogen (53.7 % of total isolates). <em>Phytophthora</em> isolates recovered from crown cankers of apple were identified as <em>P. cactorum </em>(91.5 %) and <em>P. cambivora</em> (8.5 %). The results of this study are the first report of crown and collar root rot of apple in Syria.</p>
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Kandel, Yuba R., Karl D. Glover, Connie A. Tande, and Lawrence E. Osborne. "Evaluation of Spring Wheat Germplasm for Resistance to Bacterial Leaf Streak Caused by Xanthomonas campestris pv. translucens." Plant Disease 96, no. 12 (December 2012): 1743–48. http://dx.doi.org/10.1094/pdis-03-12-0303-re.
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Bacterial leaf streak (caused by Xanthomonas campestris pv. translucens) has reemerged as a potential threat in spring wheat (Triticum aestivum) production areas in the northern Great Plains. As with other foliar bacterial diseases, chemical control under field situations is neither economical nor practical. Development of resistant genotypes will be needed for adequate management of the disease. There is currently limited information on sources of resistance in hard spring wheat germplasm. The main objective was to develop and apply a robust screening tool for evaluating germplasm against bacterial leaf streak, and to identify resistance sources for this disease. Inoculated field experiments were conducted in Brookings and Codington Counties, SD in 2009 and 2010 using a virulent local isolate (XctSD-017) inoculated after tillering stage. Forty-five hard red spring wheat genotypes with diverse genetic backgrounds were evaluated for disease severity, with ratings made at 7-day intervals from heading through dough stage. Results of this study showed clear differences in level of resistance among the 45 genotypes, with no immunity expressed. SD4205 was found resistant to the disease with the lowest area under the disease progress curve across location–years. Other genotypes showing moderate levels of resistance included SD4148, SD4176, ‘Alsen’, SD4023, ‘Faller’, SD4024, ‘Knudson’, and SD4199. Grain weight was negatively correlated to disease, as was days to heading. The resistance identified appeared to be quantitative in nature and was expressed through slower disease progress and reduced severity.
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Biggs, Alan R., Keith S. Yoder, and David A. Rosenberger. "Relative Susceptibility of Selected Apple Cultivars to Powdery Mildew Caused by Podosphaera leucotricha." Plant Health Progress 10, no. 1 (January 2009): 3. http://dx.doi.org/10.1094/php-2009-1119-01-rs.
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Apple powdery mildew thrives during dry spring and summer weather wherever apples are grown. The fungus perennates in buds, making it difficult to control and, although it can cause fruit russet, it primarily causes losses due to its chronic effect on tree vigor and yield. Data were collected over several years from 1995 (23 entries) and 1999 (22 entries) plantings of new apple cultivars and selections established at multiple locations as part of regional project NE-183. The cultivars Golden Delicious and McIntosh were the standards in both plantings. Incidence of powdery mildew on leaves and fruit was observed and data were analyzed to determine differences due to location and cultivar. One of the two planting group analyses indicated the significance of cultivar differences due to location. In general, the cultivars Ginger Gold, Suncrisp, GoldRush, Crimson Crisp, and Delblush, and the selection CQR10T17 were the most susceptible, whereas the cultivars Gala Supreme, Enterprise, Zestar, September Wonder, Hampshire, and the selections NY 75414-1 and NY 79507-72 exhibited the lowest incidences of mildew. Pinova was the most highly susceptible cultivar to mildew on fruit in Virginia, followed by Crimson Crisp and the selection NY 65707-19. Percent leaf area with mildew was related to incidence of mildew on leaves; however, fruit symptoms were not significantly related to disease incidence or severity on the foliage. Accepted for publication 11 September 2009. Published 19 November 2009.
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Burg, Patrik. "The classification of machines for vineyard defoliation in relation to production quality." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 56, no. 2 (2008): 45–50. http://dx.doi.org/10.11118/actaun200856020045.
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Defoliation fulfilment in correct terms, range and intensity effects highly on conditions of bunches and quantity of their contentual matters. Due care reduction of foliar surface together with sunshine allows better access of air to the proximity of bunches and their quicker drying up. The development of fungal diseases is not so quick. Notably hold under especially the peril of charging by cluster with Botrytis, whose harvest its possible take away to the later term. Better insolation at the same time abetment by soaking of clusters and degradation of apple acid.It is possible to make one–shot or gradual defoliation. By smaller growers can the defoliation make by hand, or near bigger with mechanization. In both cases constitute costs on implementation indispensable load sum.