Botrytis cinerea

The original producing areas and introduction areas of eight Immortals such as Zhejiang, Shanghai, Jiangsu, Hebei and Beijing all occurred in varying degrees. It harms the flowers, buds and tender shoots of many kinds of flowers and trees, such as eight immortal flowers, rose, pomegranate, green peach and so on, causing the injured part to become soft and rotten and reduce the ornamental value.

The symptom spot mainly occurs on the flower, initially produces waterlogged irregular spots on the petals, and then gradually expands, which can spread to the whole Corolla and inflorescence. When the bud is killed, it also produces irregular waterlogged spots, which can be extended to the whole bud, and finally the bud becomes soft and rotten and cannot open. After the shoot was killed, it was irregular and waterlogged at the beginning, and gradually expanded to the rot of the new shoot and tender leaves. In the warm and humid environment, the disease showed a large number of gray mildew layer in the later stage.

The pathogens were fungi and Botrytis cinerea. The pathogens overwintered mainly in sclerotia and conidia on diseased flowers, diseased shoots, diseased leaves and other diseased tissue residues. When the temperature rises in the next spring, in case of rain or high humidity, conidia are produced from the sclerotia, or conidia from other parasitic parts, which are quickly germinated and infected by airflow to the eight immortal flowers. The pathogen of the eight immortal flowers in the greenhouse and greenhouse in the north mainly came from the remains of the diseased tissue in the previous year, and the disease began to occur in the early and middle of May. Planting is too dense, rainy, wet and cool weather, as well as partial application of nitrogen fertilizer or lack of light, weak growth, are prone to the occurrence and epidemic of diseases. The high temperature and dry conditions are disadvantageous to the occurrence of the disease.

Prevention and cure method

(1) Clean the flower beds. Usually pay attention to maintain the hygiene of the protected area, find diseased flowers and diseased tips cut off in time, clean the plant remains on the ground at any time, and concentrate on burying deeply. Thoroughly clean the remains of fallen leaves in the protected area and its vicinity after the beginning of winter, concentrate and bury them deeply, and shall not be abandoned at will.

(2) strengthen cultivation management and enhance disease resistance. Planting density is appropriate to facilitate ventilation and light transmission. Pay attention to increasing the application of phosphorus and potassium fertilizer and avoid partial application of nitrogen fertilizer. Attention should be paid to keeping suitable temperature and humidity in the shed. When the temperature is on the low side, the temperature should be increased to 31-33 ℃. When the humidity is high, it is necessary to vent gas and drain moisture to create conditions that are not conducive to the occurrence of diseases.

(3) Pesticide control. In the shed with a history of onset, spray 1 / 2 times before flowering for prophylaxis, you can choose 1500 times solution of 50% propofol wettable powder or 1000 times solution of 70% methyl thiophanate wettable powder. During the florescence, 1500 times of 65% carbendazim wettable powder, 1800 times of carbendazim wettable powder and 36% thiophanate suspension can be selected.