What are the rules of the occurrence of Lagerstroemia indica brown spot?

Occurrence regularity of Lagerstroemia indica brown spot: the disease is a fungal disease, and the pathogen is Pseudocercospora litchi. The pathogen overwinters with fallen leaves in the soil with hyphae and spores. Conidia were produced in the spring of the following year, and the initial infection was caused by wind and rain. After the onset of the disease, new conidia are produced in the affected area, which can cause repeated reinfection after transmission. High temperature, high humidity and rainy weather are conducive to the occurrence and prevalence of the disease.