Licorice Disease Prevention and Control Methods and Key Technical Points

(1) Rust disease: When infected, yellowish-brown scar-like lesions appear on the underside of the leaves. After the epidermis ruptures, brown powder is released; this is the uredinium of the pathogen. From August to September, dark brown telia form, causing the leaves to turn yellow and wither, and in severe cases to fall off. Control methods: Apply more phosphorus and potassium fertilizer to improve the plant's disease resistance. Remove diseased plant debris and burn it in a centralized manner. At the early stage of the disease, spray with 15% triadimefon at 1000 times dilution, or 97% diniconazole at 400 times dilution.

(2) Brown spot disease: It damages the leaves, and affected leaves develop round or irregular lesions. The lesion margins are brown and the centers are red, with grayish-black mold-like growth on both the upper and lower surfaces of the lesions. Control methods: Clear the garden in winter and dispose of diseased plant debris. At the early stage of the disease, spray with 65% mancozeb or 50% mancozeb at 500 times dilution, or 70% thiophanate-methyl wettable powder at 1500 times dilution, or 1:1:100 Bordeaux mixture.

(3) Powdery mildew: Affected leaves look as if they are dusted with a layer of white powder, and later the leaves turn yellow, causing poor plant growth. Control methods: Clear the garden and dispose of diseased plant debris; spray with 70% thiophanate-methyl wettable powder at 1500 times dilution, or 15% triadimefon at 800-1000 times dilution.