Shadura N. Mildew of the grape and the improvement of protection measures under the conditions of the Southern Steppe of Ukraine.

The peculiarities of the development of mildew of the grape were determined under the conditions of the pre-Black Sea Lowland of the Southern Steppe of Ukraine over a period of 2000-2008. The occurence intensity and the injuriousness level of the pathogen on different grape varieties were established. Mechanisms of resistance of the grape plant to the pathogen's attacks were described. The effectiveness of a system for mildew control on grape varieties differing in field resistance was substantiated. Models of short-term and long-term prediction of mildew occurence and development for commercial grape plantings of the pre-Black Sea Lowland of the Southern Steppe of Ukraine were generated based on the data arising from long-term monitoring of the pathogen. The results of long-term research indicate that a 17-fold lowering of the disease intensity on the leaves and 23 times on the clusters enabled a reduction in direct loss of yield by 37% and more. Loss of buds went down by 84%, and increases in the numbers of developed shoots, fruiting canes and developed clusters were 18%, 14% and 27%, respectively. An increase in sugar content of the juice was more than by 20%. Regression models to predict the dependence of the grape plant's cropping capacity upon the degree of mildew development on the leaves and on the clusters were originally generated. The proportion of the effect of the degree of mildew development on the leaves and on the clusters on productivity and sugar mass concentration of the juice was determined. Zonated grape varieties were originally differentiated based on the degree of their field resistance to mildew, and the dependence of field resistance to mildew upon the biochemical compositions of the grape plant, the leaves and the clusters was studied. It was substantiated theoretically and proved experimentally that the effectiveness of protection measures on grape varieties with different resistance to the pathogen was still high (79-99%) when the number of special treatments was reduced from six to four and two. Optimal terms and frequency of treatments to control mildew on grape varieties with different field resistance were determined depending on the ecological peculiarities of the vegetation period: two to three treatments on highly resistant varieties over the periods of v?raison and industrial ripeness, three to four treatments on resistant and susceptible varieties over the periods of pea-sized berries, berry growth and berry ripening and four to five treatments on highly susceptible varieties over the post-bloom and the berry growth and ripening periods. A highly effective fungicide preparation, Pilarstine (50% s.c.). was first recommended for mildew control. The improved system of for control of mildew on the grape was evaluated from the economical standpoint. The basic results of the investigation were tested under conditions of commercial viticulture.