During the cultivation of onions, improper field management can lead to various diseases and pests, greatly affecting the yield and quality of onions. Let's learn about the symptoms and control measures of leaf rot disease in onions.
Symptoms of Leaf Rot Disease in Onions
At the onset of the disease, the tips of the leaves turn yellow, and water-soaked lesions appear at the base of the stem. These lesions then become dry and rotten, turning grayish-black. The rot extends upward along the base of the stem, causing black decay in the underground parts. Dense white fuzzy mold appears on the surface or within the tissues of the leaf sheath, gradually turning grayish-black and rapidly forming numerous sclerotia.
Control Measures for Leaf Rot Disease in Onions
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Rotate crops in severely affected areas, with a rotation cycle of 3 to 5 years. Planting should be done in disease-free areas or fields without pathogens to avoid the transmission of viruses through seeds. When transplanting seedlings, remove diseased seedlings to prevent the spread of pathogens in the field.
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Field Management: Immediately remove diseased plants found in the field and disinfect with lime powder or chemicals. Proper irrigation should be maintained, with timely drainage during the rainy season to reduce field humidity and prevent disease occurrence. After harvesting, promptly burn or bury the remains of diseased plants in the field, deeply plow the soil, and bury the pathogens in the deep layers to reduce the disease source in the field.
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Soil Disinfection: Before planting onions, soil disinfection can be carried out. Apply 46-47kg of 50-fold diluted formalin per acre sprayed on the soil surface, or mix with 20% methyl isopropyl phosphoramide emulsion. In the early stages of the disease, spray with a 500-fold dilution of 50% mancozeb wettable powder, 1000-1500-fold dilution of 40% carbendazim, or 1000-fold dilution of 50% iprodione wettable powder.
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Root Irrigation: During the growth period of onions, root irrigation with fungicides such as metalaxyl, azoxystrobin, propiconazole, or carbendazim can be selected.
Above are the introduction and control measures for leaf rot disease in onions. This disease poses a significant threat to onions, so it is essential to implement effective control measures.
