Effect of Some Organic Compounds and Cluster Thinning on Quality Characteristics and Powdery Mildew of Flame Seedless

THE APPLICATION of some organic materials, Jojoba oil, Neem oil and micronized sulfur, sprayed alone or accompanied with cluster thinning was studied on Flame Seedless grapevine. The experiment was conducted in the 2013 season and extended for two successive seasons. It comprised eight treatments to improve berry quality and limiting the powdery mildew progression. Results indicated that spaying with Jojoba oil, Neem oil had a negative effect on the propagation of Powdery Mildew ‘Uncinulla necator’similar to micronized sulfur and they could be a valid alternative control. Jojoba oil plus cluster thinning treatment was the most effective in stimulating all growth characters and increasing significantly the TSS% and anthocyanin but it lowered the yield than the Jojoba oil treatment. Yield compensation was achieved by an increase in cluster weight of about 53%, in response to a reduction of 33%, in cluster numbers. Neem oil had no significant effect on chemical composition but significantly increased yield by 43% by lowering the number of infected berries per cluster.