Environment
Peronosclerospora sorghi requires warm temperatures and high humidity for it to prosper. Oospores are usually the primary inoculum, and they are found in the soil. The soil must be moist to ensure proper germination of the oospores. Soils that have had little tillage will often stay damp longer than highly tilled soils and harbor oospores in the rooting zone of the host plant, which leads to an increased chance of infection. If the same host is grown in the same area year after year, the oospores may continue to build up in the soil, providing more primary inoculum for every following year.
There may be production of conidia if the environment is suitable. Conidia are produced when there has been rain, because moisture is a key factor in their production. Rain or high humidity causes leaf wetness, which is the optimal environment for the pathogen to produce the conidia. A normal temperature range for production is 55-75 degrees Fahrenheit. If these conditions are present, there will be innumerable conidia disseminated by the wind. The conidia is a source of secondary inoculum. If susceptible plants are being grown in the same area as these infected plants, the disease can spread rapidly as the conidia infect the surrounding susceptible plants.
Read more about this topic: Peronosclerospora Sorghi
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