Pathogen: Botrytis cinerea Pers.
Harmfulness: in the absence of timely protective measures, the disease leads to the loss of large groups of plants. When creating favorable conditions, spores of the pathogen quickly germinate, which, afterwards, leads to the death of contaminated tomatoes.
Gray rot of tomato is a fungal disease that is characteristic not only for solanaceous, but also for other vegetable crops. It affects the supremely part of the plant (leaves, stalks, and fruits) at any stage of its development. In this case, young plants are more resistant to infection. The first signs of infection appear at the fruiting stage. Most often, the pathogen penetrates tomato during its trauma. It also contributes to the spread of the pathogen, the high density of beds and the wrong care of the crop. Necessary conditions for the development of the fungus are the humidity 90-100% at high temperature (22-30C). In view of this, in greenhouse conditions, the percentage of tomatoes in gray rot is an order of magnitude higher, but the measures to control this disease and its prevention are quite high. Resistant tomato varieties are currently not released.
The first symptoms of tomato infestation with gray rot are small light gray (or light brown) spots on the leaves. Then during the next week after infection spots increase in sizes up to 4-5 cm.
During the development of the disease, light gray spots cover not only the leaves but also the stems of the tomatoes, gradually increasing in size and aggregate with each other. Soon they cover the entire stem, the leaves take light gray color. The necrosis of the blood vessels of the plant develops, which is the main reason for its fading. In rainy weather, gray rot also damages flowers, fruits of tomatoes; round spots with a noticeable sporulation appear on them.
This infection is well transmitted to tomatoes from other vegetable crops such as: cucumber, lettuce and others. The spores of the causative agent with gray rot is spread by air and with splashes of water. It is also possible to transmit the disease during the treatment of the beds through tools and clothing. Dissonance of gray rot, like other fungi, hibernates well in plant residues, in the soil can persist for up to 2 years.