What are the control methods for grape leaf blight?

Symptoms: Brown spot disease is caused by infection with the fungus Pseudocercospora vitis, and mainly damages grape leaves. In the early stage of infection, the infection sites appear as light brown, irregular angular spots. The lesions gradually expand, reaching a diameter of up to 1 cm. The lesions change from light brown to brown, and then to reddish brown, with a yellow-green margin. In severe cases, several spots merge into large lesions with distinct edges, while the margins on the underside of the leaf are blurred. In the later stage, the diseased parts die, and grayish-brown mold growth appears during rainy periods or when humidity is high.

Control methods: (1) Thoroughly remove dead branches and fallen leaves to reduce the source of infection. Before bud break, spray 3-5 degree lime sulfur mixture; (2) Chemical control: in areas with severe disease, in combination with the control of other diseases, spray 1 application of equal-amount 200-fold Bordeaux mixture in June, and from July to September spray 500-fold 50% carbendazim, 600-800 fold chlorothalonil, or 800-1000 fold 70% thiophanate-methyl alternately, spraying once every 10-15 days. 65% mancozeb can cause phytotoxicity on some grape berries, more obviously in the north, so the concentration used should be 1000-1200 fold; (3) Fertilize rationally and prune scientifically. Apply more multi-element compound fertilizer. Strengthen tree vigor and improve disease resistance, keep branches scientifically, and promptly pinch and prune, ensuring ventilation and light penetration on all sides.