Farmers warned of the risk of secondary sunflower infection with powdery mildew

Powdery mildew is spreading through early sunflower sowings in the Kharkiv, Poltava and Dnipropetrovsk regions. Warm weather and rainfall favour the spread of diseases, so care should be taken to prevent secondary infection, noted Serhii Korniushenko, Agri-technology Development Manager for the Southern region of LNZ Group.

"Because they were sown early, the plants suffered cold stress and the primary infection was not noticed in time. But there is still time to stop the secondary infection so that the fungal spores do not spread to unaffected plants. Otherwise, there is a risk of getting dwarf plants that will produce two heads instead of one," he says.

The specialist adds that he does not observe this problem in late sunflower sowings. However, such diseases as alternaria and septoria are present. And while septoria can be controlled starting from the two-to-four-leaf stage, alternaria appears as early as the 8-10 leaf stage and up to head formation. At the initial stage these diseases look similar, but there are differences.

"With septoria, dark green spots appear on the leaves of the lower tier. Then these spots gradually start to turn brown and stop at the leaf veins. After rains, the spores are spread by the wind and infect the upper leaves. As a result, the sunflower does not fill out and we can lose up to 30% of the yield. Alternaria manifests a little differently. In the early stages the disease also appears on the lower tiers. And in the later phases it often appears on the head and leads to its rotting. Yellow specks appear on the leaves, which then grow, start to brown, and the leaf takes on a dark brown colour. Then it dries out and, if you press it with your fingers, it crumbles," Serhii Korniushenko explained.

Alternaria develops at high temperatures of 25-30 degrees. Since it spreads from the lower leaves to the upper ones, timely control can save the harvest.

Source: superagronom.com