Botrytis cinerea is a common disease in tomato production in greenhouses, and it is also a kind of disease that is more difficult to prevent and control. It spreads quickly and causes serious damage. It often causes a lot of fruit rot and brings serious economic losses to vegetable growers. Through our investigation, it was found that most farmers attach more importance to the prevention and treatment after the onset of disease, but do not do enough for prevention work, which results in severe consequences after the occurrence of gray mold. Therefore, prevention should be the main focus in production, and comprehensive prevention and control should be carried out.
First, the symptoms of seedling damage can cause stems and leaves to rot, showing a green to grayish brown, dense surface of gray mold. In the adult stage, the leaves develop from the tip of the leaf to the V-shaped inward extension. The spread of the lesion is not limited by the veins. It develops rapidly when wet, and has a gray-green mold layer. The incidence of stalk stems from the extension of the petiole of the diseased leaf. When the flower is damaged, the petals and stigma are rotted and shed, and the damaged stigma often affects the young fruit. The victim of the fruit begins with the umbilicus or fruit pedicle, and the victim suffers from many diseases. On the surface of the fruit, water-soaked fading spots appear, gradually causing the whole fruit to rot, and the surface of the diseased area is covered with brown-brown moldy layer.
Second, the incidence characteristics and transmission methods Botrytis is a low temperature and high humidity type disease, the incidence of appropriate temperature 16 ~ 23 °C, relative humidity of more than 90%, of which humidity is a key factor in the epidemic of diseases, low temperature and humidity is conducive to disease. Continuous cloudy days in winter and spring, the lack of light plus ventilation and dehumidification will lead to disease epidemic.
Botrytis cinerea is a typical gas-borne disease that can spread with air, water flow, and agricultural operations. Usually there is a disease center that spreads to the surrounding areas. If it does not occur in time, it can spread quickly. The disease generally invades from plant wounds and aging organs or dead tissue and spreads to young fruit. Flower failure is the main source of infestation, and it is spread through artificial pollination in production. Therefore, the flowering period is the peak of gray mold infection, and it is also a critical period for drug control.
Third, comprehensive prevention
1. Agricultural control: Appropriate application of phosphorus and potassium fertilizers to improve plant disease resistance. Promote drip irrigation and under-membrane irrigation techniques to prevent flooding. At the beginning of the disease, the remaining petal and stigma should be removed in a timely manner to remove diseased leaves and diseased fruits and to remove diseased plants to prevent the spread of disease. Ecological control aims to increase temperature and eliminate humidity and strengthen ventilation management. Specifically, the greenhouse is warmed by closing the shed in the morning and when the temperature reaches 28 to 30°C, the top wind is released for 1 hour, and the air is released at noon, and the temperature is maintained at 20 to 25°C. When the temperature reaches 18 to 20°C in the afternoon, the vents are closed, the night temperature is maintained at 14 to 16°C, and the relative humidity is maintained at 70% to 80%. Cloudy days also have to be ventilated for short periods at noon. Prevention of flowering, flowering period is a key period for the prevention of Botrytis cinerea, this period should do the following two points: First, when the artificial pollination to change the flowers into spray flowers. Tomato Botrytis cinerea is easy to invade from floral devices. The smear method is easy to bring pathogens from diseased plants to healthy plants. Humans increase the probability of transmission and spraying will not cause transmission.
2. Chemical control: before colonization, spray the seedlings with 50% Suo Keling WP 1500 times solution or 50% Carbendazim wettable powder 500 times to prevent bacteria from entering the shed. When sprayed, add anti-growth agent to the liquid to prevent it. In the early stage of disease, 50% fasting WP 2000 to 3000 times, 50% acetaminophen wettable powder 1500 times, spray once every 7 to 10 days, spray 3 to 4 times. Spraying is usually done in fine weather. Smoke can be used in the early evening when it is closed or on a cloudy day. Under normal circumstances, smoke spray should be alternated, take a smoked a spray or a smoked two spray practice. When the weight is heavy, it can be sprayed during the day and smoke in the evening can improve the control effect. Botrytis cinerea is easy to produce drug resistance, and the amount of drug and application times should be reduced as far as possible, and attention should be paid to rotation and alternation of medication.
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