Excuse me, teacher, what happened to the tomato leaves?

1 Tomato leaf mold mainly damages leaves, but also stems, flowers and fruits in severe cases. When the leaves are infected, oval or irregular yellowish spots appear on the leaves, and gray-brown to dark-brown villous layers grow on the spots on the back of the leaves, which are the conidiophore and conidia of pathogenic bacteria. When the conditions are right, a layer of mold will grow on the front of the diseased leaves. When the condition is serious, it can cause the whole leaf to curl and the plant to be yellow-brown and dry. After the fruit is infected, a round black lesion is formed near the fruit pedicle, which is slightly sunken and inedible. Symptoms on tender stems and fruit stalks are similar to those on leaves. This disease is caused by CladosporiumfulvumCooke, a subfamily of fungi. Bacteria spread through the air and invade the human body from the pores on the back of leaves. The occurrence of diseases is mainly related to temperature and humidity. High temperature and humidity are beneficial to the onset, and humidity is an important factor affecting the onset. At the temperature of 22℃, diseases can be induced as long as there is a water film on the leaves for 4 hours. If the temperature in the shed is 20 ~ 25℃ and the relative humidity is more than 90%, leaf mold can be created out of nothing within 3 days, and it will occur in severe cases. If it is not controlled, it will destroy the shed and stop production within a week. Weak light is beneficial to the occurrence of leaf mold. The control of tomato leaf mold in greenhouse should be based on agricultural and ecological comprehensive control techniques, supplemented by chemical pesticides. 3. 1 Selection of disease-resistant varieties Among the varieties currently promoted, Jiafen 15, Jiafen 16, Jiafen 17, Zhongza No.7, Shenfen No.3, Jiahong 15, etc. Can be planted according to local conditions. 3.2 Before sowing, soak the seeds in warm water at 55℃ for 30 minutes to remove the germs inside and outside the species. After the treatment, it is best to rinse with clear water for several times to remove the germs attached to the nascent water and the surface of the seeds, and then dry the seeds in the shade. 3.3 Reasonable arrangement of greenhouse crop rotation tomato cultivation, preferably with melons or other solanaceae vegetables for three years, can effectively eliminate the residual bacteria in the soil. 3.4 Greenhouse Disinfection In the greenhouse where crops are difficult to rotate, mix 0.25kg sulfur powder and 0.50kg sawdust every 37m3 space before planting seedlings, ignite them in several places, close them for 24 hours for disinfection, plant seedlings one day later, or fumigate them with 45% chlorothalonil smoke agent for one day and night, with the dosage of 0.25 kg per100 m2, and carry out indoor and soil surface treatment. 3.5 Strengthen cultivation management, strengthen the management of temperature and humidity in the shed, ventilate in time, properly control watering, ventilate and dehumidify in time after watering, and control irrigation even in rainy days and after onset. Reasonable close planting and timely pruning and raking are beneficial to ventilation and light transmission. Implement formula fertilization to avoid excessive nitrogen fertilizer and appropriately increase phosphorus and potassium fertilizer. When the diseased leaves first appear, they should be removed in time, buried or burned in a centralized way. 3.6 The high-temperature closed shed should be selected at noon on a sunny day. The temperature in the closed shed should be raised to 30 ~ 33℃ and kept for about 2 hours, and then ventilated in time to cool down, which has a good control effect on pathogens. 3.7 Early onset should be timely medication, it is best to use dust or smoke, or spray. Dust or smoke application should be sprayed at night. Preventive medication: Scheme 1: Olysobel 30ml, water 15 kg, every 7- 10 days/kloc-0 times; Scheme 2: Olyscream Bell 30ml+ Jinbei 40ml, 15 kg water once every 7- 10 days. Scheme 2: 50ml+ of Ollie frost bell+30ml of interlayer, 15 kg of water, every 5-7 days 1 time; Scheme 3: 50ml+ of Ollie Cream Bell+30ml of Qingkulike, 15 kg of water, 5-7 days 1 time, 2-3 times in a row. Note: In order to prevent epidemic diseases, it is best to use chlorothalonil to irrigate roots at the same time. See the instructions for chlorothalonil for details. In the middle and late stage of onset: 50 ml of Olysobel+25 g of 58% metalaxyl manganese zinc or 5 g of propamocarb 1 0-/kloc-0, with water 15 kg, administered once within 3 days. 50 ml of 80% dimethomorph+10/0g, 5 ml of 25% dimethoxystrobin, within 3 days 1 time. 50ml+ Olysobel +25g of cyanamide or 20 g of propamocarb hydrochloride, 65438+0 times every 3 days.