Chapters authored
Evaluation of the Cultivar Effect on Wine Grape Fungal Diseases with a Use of a Low-Input Fungicide Regimen in Southeastern Virginia, USA By Mizuho Nita
Wine grape cultivar selection was examined as a use of biotechnology and a part of integrated plant disease management in grape and wine production. The efficacy of 18 wine grape cultivars against various wine grape diseases was examined using a relatively low-input fungicide regimen to determine whether these diseases can be managed under hot and humid southeastern Virginia conditions over 5 years. Disease developments of black rot, Botrytis bunch rot, downy mildew, Phomopsis cane and leaf spot, and powdery mildew was evaluated. Although overall level of disease was low in each year, we observed a significant (P ≤ 0.05) effect of cultivar in many cases, indicating the importance of cultivar selection. Cultivars such as ‘Norton’, ‘Noire’, ‘Traminette’, ‘Vidal blanc’, and ‘Viognier’ were found to be less susceptible to the major diseases under Virginia environmental conditions.
Part of the book: Grape and Wine Biotechnology
Synergistic Effect of a Mixture of Benzimidazole and Iminoctadine Triacetate for the Preharvest Control of Benzimidazole-Resistant Penicillium digitatum, a Causal Agent of Citrus Green Mold in Japan By Nobuya Tashiro and Mizuho Nita
Green mold, caused by Penicillium digitatum, is the leading cause of citrus decay in Japan. Due to a ban on the post-harvest fungicide application in Japan, the preharvest application of benzimidazoles has been used and demonstrated good efficacy since 1971. A benzimidazole resistant P. digitatum strain was first isolated from a packinghouse in 1974, and more cases were reported in subsequent years. On the other hand, very few cases were reported from the grove for two decades. However, by the mid-1990s, when the field incidences of benzimidazole resistant strain started to increase, the effect of benzuimidazoles became unstaible. An alternative to a benzimidazoles, iminoctadine triacetate, exhibited good antifungal activity against P. digitatum in vitro, but its efficacy was inconsistent in the field. We examined the efficacy of a mixed application of iminoctadine triacetate and benzimidazoles against each fungicide by itself based on five years of data from multiple locations. The results indicated a synergistic suppression on green mold, where the efficacy of the mixture was consistently greater than treatments with either fungicide alone. The improved efficacy was considered acceptable for a practical use by the industry, and lead to a development of a pre-mixed commercial product, Beftopsin flowable in 2006.
Part of the book: Citrus Pathology
Developing an Online Grapevine Trunk Disease Diagnostic Aid By Mizuho Nita
We face critical challenges in educating growers on wood-canker diseases of grapevines. Unlike other major diseases that appear every year with obvious symptoms (e.g., powdery mildew of grape), wood-canker diseases are often go unnoticed, yet they have more certain and detrimental effects on the plants. Because of this lack of sensational symptom development within a short period, it is difficult for agricultural educators to convince the growers to take urgent action. Modes of delivering extension-related information are changing. Reduced extension education budgets and changes in growers’ expectations have led to fewer of the standard, face-to-face meetings between extension agents and growers, and instead, have shifted toward distance-learning style approaches. In order to address these issues, we have developed a new web-based pictorial diagnostic key tool for grapevine trunk diseases. This tool aids users to determine a target grapevine trunk disease using a series of pictorial keys from different tissues of grapevines (leaves, trunks, cluster, etc.). Once enough information is obtained, it will provide the user a list of recommendations for management. This tool covers not only trunk diseases, but also some bacterial diseases and abiotic disorders that are similar in symptom expressions. It is hosted attreeandvinetrunkdiseases.org, and the website is freely available.
Part of the book: Advances in Plant Pathology
Emergence of Benzimidazole- and Strobilurin-Quinone Outside Inhibitor-Resistant Strains of Colletotrichum gloeosporioides sensu lato, the Causal Fungus of Japanese Pear Anthracnose, and Alternative Fungicides to Resistant Strains By Nobuya Tashiro, Youichi Ide, Mayumi Noguchi, Hisayoshi Watanabe and Mizuho Nita
Japanese pear anthracnose (JPA) can cause severe tree defoliation during the growing season. Infected trees become weak and produce fewer flower buds the following spring. This economically serious fungal plant disease has affected cultivated pears in Japan since 1910. Initially, JPA was controlled by benzimidazole fungicides. However, benzimidazole-resistant pathogen strains emerged in the late 1990s, and the range of JPA has expanded in Japan. Since then strobilurin-quinone outside inhibitors (ST-QoIs) such as azoxystrobin and kresoxim-methyl became popular, but ST-QoI-resistant pathogen strains appeared. By 2005, JPA control became difficult once again. In this chapter, we outline the history of JPA fungicide resistance problems, assess advantages and disadvantages of available fungicide options, and develop JPA management strategies based on evidences we obtained from a series of field and lab studies.
Part of the book: Plant Diseases
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