Agent: parasite fungus Botrytis cinerea (Pers.); Botryotinia fuckeliana (DB.) Whet.
The disease affects both the above-ground and underground parts of the plant, as well as fruits, quickly develops and infects a large area of plantations. Thus, in a short time you can lose a serious part of the crop.
Gray rot is a fungal disease that visually looks like a gray-brown plaque on fruits, leaves, cucumber bushes. Optimal conditions of this disease are high humidity and low temperature (16-17°C). With an increase to + 25-27°C and a decrease in humidity below 80%, the development of the disease stops. In greenhouses, it is easy enough to identify the agent of gray rot even at the first stages of infection, it is enough to take care of the plants.
At an early stage of the disease, infected plants can be distinguished by a characteristic gray coating on its leaves or stems. If you do not take any measures at this stage to control the disease, soon the color of the plaque changes to light brown, and in some cases even red-brown.
After the growth of spots, there is a large number of spores that infect all plants. Accordingly, the damage from gray rot in this case increases at times. Then, the spots expand and merge with each other, the infected plants visually become similar to those covered with ashes. At this stage, the plant dies.
One of the main sources of the appearance of gray rot in the greenhouse is already contaminated soil, as well as the remaining plant remains with mycelium or spores of the fungus. When creating favorable conditions, the pathogen rapidly develops and spreads to the maximum available area.
It should be noted that the agent hibernates well not only in the soil, but also on the walls and structures of the greenhouses, so to prevent the disease, clean and disinfect beds, entire room after harvesting. Other preventive measures include removal of infected plants along with the top layer of soil, pruning of affected stems and leaves, and complete control over the temperature regime in the greenhouse.