What are the control methods for yam leaf spot?
How should yam leaf spot be controlled? Seeking advice 〔Pathogen scientific name〕Septoria diocoreae J.K. Bai & Lu 〔Host crop〕Yam. 〔Disease diagnosis〕It mainly affects the leaves. When the leaves become diseased, small brown spots first appear on the leaf surface, then gradually expand into angular lesions 6-10 mm in size...
How should yam leaf spot be controlled? Seeking advice
〔Pathogen scientific name〕Septoria diocoreae J.K. Bai & Lu
〔Host crop〕Yam.
〔Disease diagnosis〕It mainly affects the leaves. When the leaves become diseased, small brown spots first appear on the leaf surface, then gradually expand into angular lesions 6-10 mm in size. The lesion edges are dark brown, the centers brown, with numerous tiny black dots on them. When the disease is severe, the leaves are covered with lesions or the lesions merge together, causing the diseased leaves to dry up and die. The pathogen is Septoria diocoreae. The pathogen's pycnidia are mainly epiphyllous, scattered or clustered, initially immersed then breaking through the epidermis, spherical to nearly spherical, dark brown; the conidia are obclavate, nearly cylindrical, with a bluntly rounded base and a rather blunt apex, straight or slightly curved, with 2-14 septa.
〔Disease development pattern〕The pathogen overwinters as pycnidia on diseased plant debris. The following year, the overwintered pycnidia release conidia for primary infection and secondary infection, and the conidia spread in the field by wind and rain. The pathogen prefers warm, humid conditions, and high temperature and frequent rain favor disease development; rain in particular is crucial for spore dispersal and germination and infection.
〔Control measures〕 (1) Select plots with higher terrain and loose, fertile soil for planting. (2) Avoid continuous cropping in frequently affected and severely diseased fields, and rotate with grain crops for more than 2 years. (3) Apply sufficient decomposed manure. Increase the application of phosphorus and potassium fertilizers, and avoid one-sided or excessive application of nitrogen fertilizer. Irrigate reasonably and drain after rain. (4) Spray chemicals in a timely manner for control at the early stage of disease onset. The chemicals can be 40% sulfur-multi suspension concentrate at 500 times dilution, or 60% Fangmeibao ultra-micron wettable powder at 800 times dilution, or 30% copper oxychloride suspension concentrate at 600 times dilution, or 30% Luyedan wettable powder at 600 times dilution, or 80% Wanlusheng wettable powder at 800 times dilution, or 50% Lide wettable powder at 800 times dilution.
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