Shaporenko V. Peculiarities of Development and Harmfulness of Oidium on grapes on the South Coast of the Crimea and Improvement of a System of Protection Measures

Biological peculiarities of the progress of oidium on grapes on the South Coast of the Crimea have been established, consisting of a super-early onset of the disease (the beginning of May), a slow progress of the disease on the leaf apparatus of the plants in the beginning of the vegetation period (May-June) and a dramatic manifestation of the symptoms on the leaves, clusters and one-year-old shoots in the second half of the vegetation period (July-August). The so-called "flag" shoots enter as the main source of primary infection. The extent of harmfulness of the disease has been determined. Yield losses on the variety Verdello which is medium susceptible to the disease vary from 19 % to 100 % (54,4 % on the average). The variety White Muscat which is very susceptible suffers 100% yield losses in the years when the disease becomes an epiphytoty. The new fungicides Cabrio Top, v.g., Microtiol Special, v.r.g., Collis, c.s. have proved to be highly effective in control of the disease, with the extent of protection of 95.9% and up to 100%. The fungicides Cabrio Top and Collis are best effective as constituents of systems of protective measures; they should be applied over the periods when the plant is especially vulnerable to the disease, prior to and after the blooming period. The fungicide Microtiol Special, v.r.g. may be very effective when applied not more than two times over the vegetation period, during hot weather, alternately with application of systemic fungicide provided the final spraying with a fungicide enabling also gray rot control. Optimum amounts of the new fungicides to be applied on grapevine to control oidium have been determined: 2 kg/ha of Cabrio Top, v.g., 3-4 kg/ha of Microtiol Special and 0,4 kg/ha of Collis, c.s. As a result of the research done, the new fungicides Cabrio Top, v.g., Microtiol Special, v.r.g., Collis, c.s. have been allowed to be used in Ukraine for control of oidium on grapevine.