Leaf mold is a common disease of pepper. Because the initial symptoms are very similar to downy mildew, it is easy to cause misdiagnosis and miss the best control period, which has a great impact on yield and economic benefits.

Pepper leaf mold mainly harms leaves. At first, it showed pale yellow and irregular green patches on the leaves, and formed a pale white mold layer on the back of the leaves. Soon, the front of the leaf becomes a large number of pale yellow to yellow spots, which are not limited by the veins, and the mold layer on the back of the leaf gradually becomes light gray to dark brown villous mold. With the development of the disease, the leaves gradually become mottled from bottom to top, and turn yellow and dry in severe cases. Compared with downy mildew, the leaves of leaf mold have no obvious embrittlement, thickening and curling, and rarely fall off in the later stage. The onset of leaf mold started from the lower leaves, and downy mildew mostly started from the middle leaves.

Second, the transmission route of pepper leaf mold

The pathogens of pepper leaf mold are mainly mycelium and conidia in the residue or mycelium lurking in seeds or conidia attached to seeds for overwintering. In the second year, conidia are produced under suitable environmental conditions and spread through airflow, running water or other agricultural operations. Pathogenic conidia produce germ tubes, which mainly invade from stomata on the back of host leaves. Later, conidia were produced on the lesion for reinfection.

Third, the causes of pepper leaf mold

1, pepper leaf mold mostly occurs in the middle and late stages of planting in various protected areas in early spring.

2, if the temperature rises, watering too much, extensive management. Continuous rainy weather, poor light, poor ventilation and long-term high humidity in the reserve are conducive to the spread and aggravation of leaf mold.

3. Pepper plants are easily infected when they are cultivated too densely, grow in closed fields, dry and wet alternately, or when pests such as whitefly occur. Pathogenic spores spread rapidly with the wind.

Fourth, preventive measures of pepper leaf mold

1. Before sowing, pepper seeds should be dried for 2 ~ 3 days, then soaked in warm water at 55℃ 15 ~ 20 minutes, stirred continuously, and then dried to sow. Soak seeds in 800 times solution of 1% potassium permanganate for 30 minutes, take them out and rinse them, and then accelerate germination.

2. Select disease-resistant varieties, such as Shouguang Changyao pepper, Zhongshu No.4, No.5 and Sujiao No.5. ..

3, found that the diseased plants and leaves should be removed as soon as possible, centralized burial or incineration.

4. Remove plant residues in time after pepper harvest.

5. Try to avoid the sudden wet and dry phenomenon of pepper field. No irrigation, pay attention to reduce the humidity in the field, especially the air humidity in the protected area.

6, pepper and onion, garlic stubble or rice rotation. When preparing soil, 2,250 ~ 3,000 kilograms of quicklime should be sprinkled per hectare, and the applied organic fertilizer should be fully decomposed.

7, found that the late illness, can be first 36 ~ 38℃ high temperature stuffy shed. Before planting in the greenhouse, each hectare of ground can be sprinkled with quicklime 1 125 ~ 1200 kg, and then deeply turned twice, disinfected with lime, which can supplement calcium.

Five, pepper leaf mold control pesticides

Before planting pepper in the greenhouse, fumigate the greenhouse or greenhouse with sulfur powder. Spraying 800 times of 47% Garinon WP, or 10% Baolian WP, 1000 times of Wanmeiling WP, or 1000 times of 75% chlorothalonil WP before or at the beginning of the disease, and spraying 1 0 every 7 days. In addition to spray control, 6.5% metformin powder or 5% chlorothalonil powder can be used in the protected area, and the dosage is 22.5 ~ 27 kg per hectare. You can also use 45% chlorothalonil smoke agent.