Symptom Identification and Control Methods for Ginger Leaf Blight

[Pathogen scientific name] Septoria zingiberis

[Host crop] Ginger.

[Disease diagnosis] It affects the leaves. When the leaves become diseased, small water-soaked spots appear at first, and after gradually expanding, the lesions become nearly fusiform, light brown, with a grayish-white center; later the lesions extend upward and downward into long streaks. Many small black dots are scattered on the lesions. In severe cases, the lesions may split longitudinally, and the leaves die. The pathogenic fungus is Septoria zingiberis. The pycnidia are superficial or borne on both sides of the leaf, spherical or subspherical, dark brown, and contain many conidia. The conidia are filiform, nearly straight or curved, colorless, with 2 to 6 septa, mostly with 3 to 4 septa.

[Disease development pattern] The pathogen overwinters in the soil with diseased residues as mycelium and pycnidia. The following year, the overwintering fungus produces conidia that infect and cause disease in the field. After the disease occurs, conidia produced in the diseased parts are spread by wind and rain for secondary infection, causing the disease to spread rapidly and worsen. Hot and humid weather with continuous rain favors the occurrence and development of the disease. In addition, continuous cropping, low-lying planting sites, poor soil, insufficient fertilizer, or excessive nitrogen fertilizer all favor disease occurrence.

[Control measures] (1) Choose plots with higher, drier terrain and fertile soil for planting. For low-lying flat land, use high ridges or high beds for cultivation, and make deep furrows for drainage. (2) Apply sufficient decomposed manure and topdress in a timely and appropriate amount. Do not apply too much nitrogen fertilizer, and pay attention to increasing phosphorus and potassium fertilizer, especially potassium fertilizer. (3) Irrigate scientifically, drain water after rain, and reduce field humidity. (4) Avoid field operations after rain or when dew has not yet dried, so as to reduce opportunities for disease transmission and lessen disease occurrence. (5) Spray chemical agents promptly for control at the early stage of disease onset. Optional agents include 30% Ludebao suspension concentrate at 300 times dilution, or 30% copper succinate-glutarate wettable powder at 400 times dilution, or 64% Sandofan wettable powder at 500 times dilution, or 80% Wanlusheng wettable powder at 800 times dilution, or 68% Beideli wettable powder at 800 times dilution, or 80% difolatan wettable powder at 500 times dilution.