Influence of sowing dates on resistance to diseases and productivity of sunflower in Tambov region

For the years of researches, first two sowing dates (first one - at soil warming-up on a depth of seed planting up to 8-14°С and the second - five days later) were the optimal for sunflower variety Chakinsky-931. Distribution of the radical form of white rot was in 1.3-2.0 times lower than at the latest sowing date (25 days later early sowing date), and productivity was the greatest - 2.38-2.34 t ha-1. At average sowing dates (10-15 days after early planting), productivity decreased on 0.10-0.15 t ha-1, and at the late one (20-25 days after early planting) on 0.24-0.40 t ha-1, at the average for two years of researches.