In raising the yield of grain crops, an important place belongs to the fight against their diseases, which, if massively spread, can lead to a significant decrease in grain harvest and deterioration in its quality, and sometimes to the death of individual areas under crops.
Spots are especially harmful on wheat, barley and many cereal grasses. Depending on the type of pathogen, the affected plant and the nature of the manifestation, these diseases received different names.
Specialists of the Rosselkhoztsentr in the Stavropol Territory conducted a survey of winter barley crops for infection with seedling diseases on an area of 11.3 thousand hectares. As a result of monitoring, infection of 2.6 thousand hectares with dark brown helminthosporiasis and 2.2 thousand hectares with net blight was detected.
Dark brown helminthosporiasis appears both on seedlings and on adult plants. Affected seedlings often have one root instead of three. Longitudinal dark spots in the form of strokes and stripes appear on the coleoptile and the first leaves, the sprouts are bent and die.
Dark or light brown spots appear on the leaves of older plants, lighter in the center, with a dark border, slightly elongated along the length of the leaf.
The development of the disease is enhanced by rainfall and elevated air temperature, in the autumn-winter period.
The causative agent of dark brown spotting is Drechslera sorokiniana Subran.
The first visual symptoms of net helminthosporiasis can be seen during the tillering period.
A characteristic sign of the disease is the appearance on the leaves of oval brown spots with a pale yellow rim, covered with a mesh pattern consisting of transverse and longitudinal stripes.
The mesh type is characterized by the formation of necrosis with a mesh pattern, surrounded by light green, gradually turning yellow areas of various sizes. With a far advanced pathological process, the affected areas merge, which entails the rapid death of the leaves.
The causative agent of the disease is the phytopathogenic fungus Drechslera teres.
For the treatment and prevention of barley helminthosporiasis, the Regional Rosselkhoztsentr recommends that farmers be treated with biofungicides at an air temperature of + 0 °C.
Full version on the site How to distinguish net helminthosporiasis of barley from dark brown