What is sorghum purple leaf spot? A disease you need to know about when growing sorghum
What is sorghum purple leaf spot? How can it be controlled well? Please give an introduction. Sorghum purple leaf spot mainly occurs in the middle and late stages of sorghum growth and damages leaves and leaf sheaths. The lesions are purplish red, oval or oblong, mostly confined between parallel leaf veins, sometimes with a light purple halo, and on the underside of leaf lesions a gray mold layer develops; on leaf sheaths...
What is sorghum purple leaf spot? How can it be controlled well? Please give an introductionSorghum purple leaf spot mainly occurs in the middle and late stages of sorghum growth and damages leaves and leaf sheaths. The lesions are purplish red, oval or oblong, mostly confined between parallel leaf veins, sometimes with a light purple halo, and on the underside of leaf lesions a gray mold layer develops; lesions on leaf sheaths rarely produce a mold layer. The sorghum purple leaf spot pathogen overwinters as mycelium or conidia in diseased plant residues and is the primary infection source for the following year. After disease occurs in the field, conidia produced on the lesions spread through airflow and cause repeated secondary infections. The development of the disease is closely related to climate; generally, in years with high temperatures and abundant rain, the disease is severe.
Control methods for sorghum purple leaf spot:
1. Agricultural measures: After autumn, plow deeply in time and bury diseased residues deep in the soil. In the late stage of sorghum growth, topdress in time and apply more phosphorus fertilizer to enhance the plant's disease resistance.
II. Manual control: Sorghum purple leaf spot first appears on the lower leaves and gradually develops upward, so remove the lower 1-2 old leaves of the plant as early as possible; this not only helps ventilation and light penetration but also reduces transmission of the pathogen.
III. Chemical control: At the early stage of disease occurrence, choose 65% zineb wettable powder at 600 times leaf solution, or 50% thiophanate-methyl wettable powder at 1000 times solution, and spray 50-75 kg per 666.7 sq m.
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