The main pathogens: fungi Pythium debaryanum Hesse, P.ultimum, P.aphanidermatum, species of the genus Fusarium.
Harmfulness of this disease leads to the rapid death of young and already fruiting plants, which naturally affects the yield of the entire site. Root rot is a common fungal disease that affects not only cucumber bushes, but also other vegetable crops. The pathogens spread throughout the greenhouse in the short time if there are no control measures taken. This causes the loss of the crop.
The spread of the agent occurs most often with sudden temperature variations, low illumination, high soil and air humidity, and also at extreme temperatures - up to 16°C or above 28°C.
Sometimes it is not possible to distinguish the infected plant at the seedling stage. The first symptoms of root rot are already evident after transplanting of grown plants. The first to become infected are shoots with a root system damaged during transplantation. The agent easier penetrates into the stem and spread further through the weakened rootstock. After the spores of the fungi are easily transferred to surrounding plants: through the air, through watering through splashes of water, through hands, clothing and equipment, etc.
The disease affects the root crown, basal stem and the root itself, and leads to its drying up the entire plant. Single oblong spots of brown color help to recognize this disease, they cover the basal stem and all the rhizome, which in the course of development grow and merge with each other.
In greenhouses the cucumber is susceptible to root rot disease not less than in the open ground. Excessive density of rows and improper care of plants enhance infection that is facilitated by watering cucumber beds with cold water (about 10 °C), too frequent watering, a large concentration of salt in the soil, its excessive dryness. Winter period, the fungus-pathogen both tolerates in plant residues, and the soil itself.