How to control Botrytis cinerea of flowers in greenhouse and the main points of sowing flowers in different seasons

Gray mold is an important disease of greenhouse flowers, mainly damaging flowers, fruits and leaves. It often occurs during the growing season of flowers, especially during winter and spring greenhouse growth. If the management is relaxed, it is more conducive to the occurrence and epidemic of the disease, which can cause a large number of fallen flowers and leaves, affect the flowering of plants and reduce the ornamental value.

Pathogen and conditions of occurrence

Gray mold is caused by Botrytis cinerea, a subphylum of semi-fungi. The fungus adheres to the diseased body by mycelium or conidia or sclerotia, or remains in the soil for winter. The optimum temperature for the growth of this bacterium is 10℃ to 32℃, the lowest temperature is 4℃, and the relative humidity is required to be kept above 90%. Due to the suitable temperature in spring, the humidity in the shed is large, such as the wind is not timely, which is the main reason for the serious disease. Main symptoms of the disease: the pathogen invades from the stomata or wounds of calyx hairs and flower pedicels, spreads to the fruit pedicels, the pericarp is gray and water-stained soft rot, a large number of gray mold layers are produced on the fruit surface when humidity is high, and the diseased flowers fall on the leaves, which is easy to cause the disease of leaves and form large round spots of gray mold. Rotten flowers, rotten fruit fall on the stem caused by stem rot, serious plant death. For example, when chrysanthemum leaves are damaged, the edges of the leaves are brown spots, the surface is slightly wrinkled, the petiole and flower stalk soften first, and then the appearance decays. When the leaves of inverted golden bell are damaged, the diseased leaves gradually turn black and brown after appearing water-stained spots, and decay. In addition, gerbera, cyclamen is also vulnerable to harm.

control methods

1. Seed disinfection. To kill fungi attached to the surface of flower seeds, seeds can be soaked in 10% trisodium phosphate solution for 20 minutes and rinsed with running water for 40 minutes before use. It can also be soaked in warm water at 52℃ for 30 minutes and dried for later use.

2. alien planting. Pathogens mainly winter in the soil, therefore, whether garden or potted, all requirements of the soil is disease-free new soil, and pot soil, flower pots, seed balls for disinfection.

3. Management in the shed. Remove diseased leaves, diseased flowers, diseased fruits and yellow leaves in time, keep the shed clean, and achieve good ventilation and light transmission. High temperature stuffy shed bacteriostasis. At the early stage of growth and after disease onset, water should be properly controlled and late ventilation should be timely. Raising the temperature of the shed to 33 ° C is detrimental to the production of differentiated spores. Reduce humidity and reduce dew condensation on canopy and foliage.

4. Chemical control. At the beginning of the disease, 45% chlorothalonil smoke agent can be used, or 15% Sukeling fumigation for 3 to 4 hours (250 grams per mu greenhouse). 5% chlorothalonil dust (1 kg per mu greenhouse) can also be sprayed in the evening. Spray method can be used 65% Zineb wettable powder 500 times solution, spray once every 10 days, continuous spray 2 to 4 times (interval 7 to 10 days). 50% procymidin 1000 times or 50% carbendazim 1000 times can be sprayed alternately every 7 days for 2 to 3 times continuously at the initial stage of disease, which can effectively control the occurrence of gray mold.

5. Rational fertilization. Try to apply decomposed organic fertilizer, increase phosphorus and potassium fertilizer, improve the disease resistance of plants, and pay attention to controlling the amount of nitrogen fertilizer to prevent excessive growth and aggravation of diseases.