Abstract:In order to illuminate the influences of sunflower sowing dates on preventing Homoeosoma nebulellum and Verticillium dahliae, confection sunflower and oil sunflower were planted in seven sowing dates, every five days from 11 May to 10 June 2009 in Bayannur, Inner Mongolia Autonomous Region. The occurrence of H.nebulellum and V.dahliae was investigated. The results indicated that the minimum infestation rate and the minimum density of H.nebulellum of confection sunflower and oil sunflower were plants sowed on 26 May, with 8.00%, 4.00% and 0.14, 0.16 larvae per flower respectively. With the sowing date delayed, the V.dahliae incidence of confection sunflower and oil sunflower declined from 98.67% and 100.00% on 11 May sowed plants to 24.00% and 32.00% on 10 June sowed plants. The V.dahliae disease grade declined significantly from 2.83 and 3.27 on 11 May sowed plants to 0.36 and 0.64 on 10 June sowed plants. The maximum yield of confection sunflower was sowed on 31 May, while oil sunflower on 5 June. Therefore, timely delay sowing would reduce the infestation rates of H.nebulellum and V.dahliae.