MySheen

Downy mildew of Impatiens

Published: 2024-11-05 Author: mysheen
Last Updated: 2024/11/05, Plasmopara obducens (Schrtiter)Schroter is harmful all over the world. It mainly damages leaves and reduces ornamental value. Symptoms The primary chlorotic spots on the affected leaves are irregular and turn yellow or brown necrotic spots in the later stage; there are white moldy things on the back of the leaves, thick and dense, and the whole leaves can be covered when serious, causing the leaves to be scorched and affecting the viewing. The pathogen is called Peronospora balsamina, which belongs to oomycetes. 2 - 5 branched-cyst peduncles, protruding from stomata,

Impatiens downy mildew, known as Plasmoparaobducens (Schrtiter) Schroter, is harmful all over the world. It mainly harms the leaves and reduces the ornamental value.

The primary chlorotic plaques on the affected leaves were irregular and became yellowish brown or brown necrotic spots in the later stage; there was a white mildew on the back of the leaves, which was thick and dense, and the whole leaf could be covered when it occurred seriously, resulting in scorched leaves and affected ornamental.

The pathogen is called impatiens axis downy mildew, which belongs to oomycetes. 2Mel 5 branches cyst peduncle, protruding from stomata, upper uniaxial branch 4 Mel 7 times, terminal branch straight, conical, apex obtusely flat; sporangium size 10-27 × 10 Mel 18 (um), nearly round.

The disease has an annual cycle and there is no obvious overwintering period. In the north, the pathogen overwinters in the soil with oospores. In the following year, the oospores were transmitted by current or Rain Water sputtering in a suitable environment. In the south, the pathogen carried out primary infection and re-infection with sporangia. After sporangium germinated, the sporangia produced by the disease were transmitted by airflow and re-infected, so that the disease spread. Temperature 15 ℃, high humidity or large temperature difference between day and night, heavy fog, heavy soil viscosity, low-lying terrain are easy to occur; summer and autumn continuous rain, rainy days, heavy rainfall serious disease or pandemic.

Prevention and cure method

The main results are as follows: (1) strengthen cultivation management, fertilize and irrigate reasonably, adjust ventilation and light transmission, and improve plant resistance. Select high-lying land for planting, timely drainage after rain, maintain appropriate temperature and humidity, clean up the disease residue, and reduce the source of disease.

(2) select disease-resistant varieties.

(3) at the initial stage of chemical prevention and treatment, 70% ethylphosphine manganese zinc wettable powder 500 times solution or 64% germicidal alum wettable powder 400% 500 times solution, 72% Kelu wettable powder 600 times solution, once every 10 days, prevention and treatment 2 Mel 3 times.

Commonly used agents ethyl phosphine manganese zinc wettable powder, disinfectant alum wettable powder, Kelu wettable powder.

 
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