The causative agent is the fungus Cercospora libicola Ell. et Ev. out of order Hyphomycetales
Cercosporosis is a plant disease that primarily affects leaves, less commonly, stems and petioles. The manifestation of the first signs usually occurs in June and is noted on fully developed leaves.
Symptoms of Cercosporosis
Cercosporosis appears on the leaves and stems of the plant in the form of rounded spots with a diameter of 2-4 mm. Color – red-brown, in the center – ashen. With increased humidity, sporification sites of grayish plaque are formed. After that, in dry weather, the leaf tissue falls out and holes appear. Over time, spots merge and cover their entire surface of the leaves. The harm from the disease boils down to the fact that the plant has to form new leaves, which takes too much energy, nutrients, and as a result, the size of root crops, and hence the yield, is reduced.
The methods of combating cercosporosis include the collection, as well as the destruction of fallen leaves, the introduction of optimal doses of mineral fertilizers into the soil. The most effective method is thorough and timely tillage in rows and row spacings. Chemical treatment must be done immediately after the first signs of the disease appear on the leaves.