The sunflower seeds as the source of preservation and spreading of phomopsis

The article provides the research results on harmfulness and on the possibility of seeds infection under the occurrence of Phomopsis only on sunflower stalks without symptoms of heads affection. The sooner the sunflower plants are infected, the higher the disease harmfulness. The affection of sunflower stalks by Phomopsis influences both sowing qualities and productivity characteristics of seeds. The seeds quantity per one head in comparison with control decreases by 1.5-86 times; the seeds weight per one head decreases by 3-53 times, one thousand seed weight - by 1.5-4 times. The laboratory germination ability decreases by 18.2-22.2 %, the field germination ability - by 5.3-14.6 %. Yield losses make from 0.08 to 0.36 t/ha. The seeds infection by Phomopsis in sunflower heads is possible not only by anemochorous way but also through vessels and other stalk tissues by 2 species of pathogen - Ph. helianthi and Ph. arctii. The phyto examination revealed that sunflower seeds with affected stalk bear the infectious Phomop-sis origin. Such plants made 55 % in our researches. 38.0-100 % of seeds (kernels) infected with Ph. Helianthi was found in the heads of these plants. The main part of them was from the plants infected in filling phase. The formation of perithecia on seeds surface is observed under longer cultivation of seed kernels from infected plants on potato glucose agar (28-30 days) in the conditions close to natural, of air temperature fluctuation from 13.0 to 28.0 °C, light period of 15-16 hours and day light without additional sources of lightning.