Optimization of chemical control of Pseudoperonospora cubensis on cucumber in Ukraine |
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| Authors: | VS Chaban VN Okhrimchuk VG Sergienko |
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| Institution: | Institute of Plant Protection, Ukrainian Academy of Agricultural Science, Vasikovskaya 33, Kyiv (Ukraine);e-mail: |
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| Abstract: | Downy mildew ( Pseudoperonospora cubensis ) is one of the most harmful diseases of cucumber in Ukraine. At high disease severity, the growing season is considerably shortened and yield is reduced. The most effective method of control is the development of resistant cultivars but, in the absence of absolutely resistant forms, control with fungicides remains very important. The effectiveness of such treatment depends on the dates of application, the number of sprays and the efficacy of the fungicides used. An improved scheme is presented, based on three components: use of cultivars with increased resistance; application of highly effective systemic + contact fungicides; and reliable short-term forecasting of disease appearance. The predictors for downy mildew forecasting are: sum of effective temperatures, weather index, duration of leaf wetness, concentration of sporangia in air and latent period of disease development. These conditions determine'critical days'for disease development. The first fungicide spray on less susceptible cultivars is recommended on the first critical day, and the next on the day of appearance of first disease symptoms. This scheme allows the fungicide load to be approximately halved, while ensuring higher yield. |
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