Pathogen: fungus Botrytis cinerea Pers.
Pseudoparasite damages weak plants. In a greenhouse, the disease appears mainly in the winter.
The development of the disease is facilitated by temperature variations and increased humidity of air (85% and above), which leads to the formation of condensation in plants. The optimum temperature for the fungus is 20 °C.
On the petals there are light spots, which in time increase and connect with each other and the flower rotates.
The bud and shoot are covered with brown spots and fluffy gray mold. The disease develops from the top down.
Plant residues form sclerotia with spores of the pathogen, which are the main sources of the disease. Infection is carried out by air-contact, often spores are carried with drops of water. Lack of micronutrients and excess nitrogen in the diet can also contribute to the disease.