How is the gourd seedling turning brown?

This is a gourd infected with early blight.

The leaves, fruits, stems and vines of cucurbits can all suffer, but the leaves suffer the most. At the beginning of the disease, the lesion is waterlogged brown, gradually expanding, slightly concave, dark brown, gray-white in the center, with micro-wheel lines, and in severe cases, the leaves are scorched. The gourd fruit is damaged, and the round diseased spot often has cracks.

Pathogens mainly overwinter in dormant mycelium and conidia of seeds, diseased residues or other hosts. The conidia on the lesion were repeatedly infected by airflow, wind, rain and insects. The temperature is high, the environmental humidity is high, and the disease is serious during the fruit-setting period of gourd.

Control method: 500-600 times of pesticide 72% Tobankelu wettable powder, 75% chlorothalonil, 70% mancozeb, 58% metalaxyl manganese zinc and 25% rifamycin wettable powder can be sprayed; 200-300 times of 40% ethyl phosphate wettable powder; Bordeaux solution 1: 1: 200 times solution; 800 times solution of 64% antiviral alum M8 wettable powder was used for prevention and treatment.