Prevention and control of blight

Rhizoctonia solani is caused by Rhizoctonia solanacearum subphyla fungal infection, with a wide range of hosts. In addition to Solanaceae and melons, some leguminous and cruciferous vegetables can also be killed, mainly harming the stem base or underground roots of seedlings. It does not produce floc white mold, does not lodge and develops slowly, which can be distinguished from catchment. Let's take a look at the prevention and control of Rhizoctonia solanacearum.

Symptoms of blight disease

Rhizoctonia solani mostly occurs in the middle and later stages of seedling cultivation, mainly harming the stem base or underground roots of seedlings, initially oval or irregular dark brown disease spots, early daytime wilting, night recovery, disease parts gradually sunken and overflowing, and some gradually become dark brown. When the disease spot expands around the stem for a week, it finally dries up and dies, but it does not lodge, and the lightly diseased plants only see brown sunken disease spots but not die. Light brown arachnoid mildew can be seen in the disease part when the seedbed humidity is high.

The incidence regularity of blight disease

The pathogen overwintered in soil or diseased tissue with mycelium and sclerotia. It was saprophytic and could survive in soil for 2 ~ 3 years. It was transmitted by Rain Water, running water, bacterial compost and farm tools. The suitable temperature for the development of the pathogen was 20 ~ 24 ℃, and both the newly unearthed seedlings and large seedlings could be harmed, which usually occurred in the middle and later stages of seedling cultivation. Most of them occurred in the seedling stage with high bed temperature or in the later stage of seedling cultivation, overcast and wet, over-sticky soil and serious disease caused by continuous cropping. The disease can be easily induced by over-dense sowing, untimely seedlings and high temperature.

Agricultural control of blight disease

1. Agricultural prevention and control: strict selection of germ-free new soil with nutritious soil to raise seedlings, seedling bed soil treatment can be mixed with 40% chloronitrobenzene and 41% poly (pyrimidine), with a ratio of 1 ∶ 1, or 38% cuproloxil, 2550 ml per mu, evenly sprayed on the seedbed. The implementation of rotation, rotation with Gramineae crops can reduce the disease. The melon field was turned 25cm to 30cm deep in autumn, and the topsoil germs and diseased bodies were turned into the deep soil to rot and decompose. The land is flat and suitable for sowing, and it is generally appropriate to start sowing when the ground temperature of 5 cm is stable at 12: 15 ℃. After emergence, the diseased seedlings should be removed in time, and the hardening should be broken by ploughing after rain, so as to increase the soil temperature, make the soil loose and aerate, and enhance the disease resistance of melon seedlings.

2. Biological control: when raising seedlings, spray the seedling bed with the root type according to 2 grams per square meter. Before and after planting, the solution can be diluted by 1500 to 3000 times, and each plant can be irrigated with 200 milliliters of root, once every 3 months.

3. Seed treatment: the dosage of seed dressing is 0.2-0.3% of the dry seed weight, and the commonly used pesticides are seed dressing agents such as mixed seed Shuang, Dixong, Miaoyanjing, Licobacter, etc., and the ratio of seed coating agent to melon seed is 1 ∶ 25 or as described.

4. Chemical control: at the initial stage of the disease, 38% carbendazim 800x solution, or 41% poly-pyrimidine 600x solution, or 20% methyl ibuprofen EC 1200 times, or 72.2% Prike water agent 800x solution, once every 7 days, can be sprayed. Or the general + door god diluted by 600 times the liquid, 3 liters per square meter before sowing or after sowing and before planting. At the time of planting or after planting and before the expected disease occurrence period, the product was diluted with 600 times solution and irrigated with roots, and the drug was used once every 7 days, depending on the disease.