Symptoms: The leaves are damaged. At the beginning of the leaves, there are water-immersed, pale green spots, which gradually expand into yellow or yellow-brown polygons or irregular shaped lesions. The edges are not obvious, and white frost on the back. mold. This is a typical Chinese cabbage downy mildew. After the package of heart disease, appropriate environmental conditions, exacerbated the disease, lesion contiguous the leaves turn yellow, dry, wrinkled volume, from the outer to the inner leaf development, dry layers, the last remaining central bag ball. Scotias,PVC Flooring Accessories T-moulding,Floor WPC End Cap,Wpc Stair Nose For Stair JIANGSU PERFECT NEW MATERIAL TECHNOLOGY CO., LTD. , https://www.bffloor.com
Prevention and cure of Chinese cabbage downy mildew
Disease cycle: pathogens mainly use oospores to overwinter in the soil with diseased residues. They can also attach oospore to the surface of seeds or mix them with seeds in the winter. The next year, they infect spring vegetables and produce a large number of oospores, as long as the conditions are suitable. The oospore can germinate after a short period of 1-2 months of inactivity, infecting the Chinese cabbage in the fall.
Route of transmission: In the field, the downy mildew of Chinese cabbage is mainly spread by air current and rainwater. It can be reinfected many times during a growing season, which is the spread of disease. There are usually three stages in downy mildew: 1) the initial period. Prior to emergence from 5 true leaves, field seedling emergence few disease, thus forming a development center, spread to the surrounding. 2) The Pfeiffer Period. More than 10 days after the initial period, about 9-10 pieces of true leaves in the seedlings, the diseased plants rose rapidly and generally occurred, but the condition was not serious. 3) The epidemic period. After Pfeiffer period, the condition quickly worsened, then enter the epidemic.
Onset conditions: cabbage downy mildew occurs mainly popular with its climatic conditions, cultivation conditions. 8 to 12 degrees spore germination, invade suitable temperature 16 degrees. Weather conditions mainly affect the temperature and humidity of the most important. Temperature determines the morning and evening and the speed of development of the disease, and the amount of rainfall determines the severity of the disease. The growth and prevalence of spore sacs are lower than the temperature at which the germination and germination are lower, the temperature is lower than 18 degrees, the temperature is warm and the night is cold, the temperature difference is large, and the rainy, high humidity or fog is heavy. In addition, the impact of the microclimate in the field is also great. The field is dense and humid, and condensation often occurs at night. Even without rain, the condition will develop.
Chemical control: After the occurrence of the central diseased plant in the field, timely drug control: use 66.8% propyl carbendazim 600 times; 80% enoylmorpholine water dispersion granules 2000 times; 60% propyl sensitis ; 58% nail cream · manganese zinc wettable powder 500 times; 52.5%% ketone · frost urea cyanide water dispersion granules 1800 times; 25% pyraclostrobin emulsion 1500 ~ 2000 times; depending on the disease interval 7 ~ 10d Once, use 2~3 times in a row.
Total 1 | <First <Prev 1 Next> Last> |
share to: