Control of Ergot ( Claviceps purpurea (Fr) Tul.) with New Pesticides
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PROTECTION
Control of Ergot (Claviceps purpurea (Fr) Tul.) with New Pesticides T. K. Sheshegovaa, * and L. M. Shchekleinaa aRudnitsky
Federal Agrarian Scientific Center of the Northeast, Kirov, 610007 Russia *e-mail: [email protected]
Received February 24, 2020; revised March 15, 2020; accepted March 30, 2020
Abstract—The studies were carried out at the Federal Agrarian Scientific Center of the Northeast during the period from 2013 to 2017 and in 2019. Model experiments tested seventeen chemical and biological preparations for the ability to limit the germination of sclerotia of the fungus Claviceps purpurea Fr. Tul. The dynamics of growth of mycelium of the fungus Spacelia segetum Lev. have been studied in paired microbial associations (in vitro). The experiments had three replications, and in vitro studies had four replications. The highest biological efficacy was found in the new Turion fungicide, which averaged 90% for 3 years. The Bunker, Dividend Star, and Vitazit preparations showed quite high efficacy (70–80%). In these variants, sclerotia that preserved their viability formed 2–6 stroma with fruiting bodies, while they formed 3–27 stroma in the control variant. Among biofungicides, Pseudobacterine had the highest efficacy (69%). Despite the same active ingredient, all preparations were found to significantly differ in antibiotic properties; therefore, the work with fungicides is individual. A series of laboratory experiments revealed a marked and prolonged antagonism in the biosystem Spacelia segetum–Streptomyces hygroscopicum, strain А-4. The sterile area around S. hygroscopicum averaged 1.95 cm2 for all isolates. It was maintained after 14 days of incubation of the test culture, which makes this strain promising for the construction of a new target biopreparation. Weak inhibition in growth of S. segetum colonies was found in the presence of the fungus Acremoniella occulta and the bacterium Flavobacterium fulvii, strain L-30. Keywords: ergot (Claviceps purpurea, Spacelia segetum), viability of sclerotia, biological and chemical preparations, paired microbial associations, biological efficacy DOI: 10.3103/S1068367420050183
INTRODUCTION Ergot (Claviceps purpurea Fr. Tul.) is almost everywhere becoming one of the progressive diseases of not only winter rye but also many grain crops [1–7]. Measures to combat it are difficult due to the complex biology of the pathogen—the fungus C. purpurea, which has several infectious structures, wintering sclerotia, ascospores (spores of sexual reproduction), and conidia (spores of asexual reproduction), that infect the ovary of flowers. Formed sclerotia are often close in size to seed kernels of the host plant. Therefore, despite a fairly multistage technological scheme for cleaning the grain mass, it is not possible to get rid of sclerotia by mechanical sorting, and some of them inevitably get into the seed and food batches of grain [8], which become one of the important sources of ergot conservation and spread. An important method of combating the disease is the tr
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