Scallion soft rot is a common disease in scallion production. In recent years, high temperatures, high humidity, and rainy weather have occurred throughout the country, which is conducive to the occurrence and spread of large areas of the disease.
First, the harm symptoms. Scallion soft rot generally occurs during the expansion of bulbs, which mainly damages bulbs. At the early stage of disease, the bulbs became watery, and the base of the leaf sheath began to soften and spoil. This eventually led to lateral folds of the outer leaves, and the lesions spread downwards. The interior of the soft rot disease began to rot within the late period of onset, and a foul odor was emitted. Scallion soft rot is a kind of bacterial disease. Diseases and residues in fields of leeks, unfertilized soil and harmful insects are all sources of soft rot.
Second, prevention and treatment methods. One is after the rain row out. After the onset of heavy rainfall in the lush green field, we must promptly drain the water from the fields and prevent the roots from being exposed to rain for a long time. The second is ploughing. After heavy rain, the soil tends to show consolidation and the degree of soil salinization increases, and the metabolic activity of welsh onion roots weakens.
Third, pest control. At present, it is the high incidence period of pests such as onion thrips, leaf miners, and root cockroaches, which often damage the leaves or roots and cause the rapid spread of the disease. The control of onion thrips can be controlled with 2.5% high efficiency cypermethrin 2000 times spray and the control of leaf miner can be controlled with 10% imidacloprid 1000 times spray. The control root can be treated with 50% phoxim diluted 800 times before rooting.
Fourth, chemical control. In the early stage of onion rot, 72% agricultural streptomycin sulfate 4000-fold wettable powder or 77% copper hydroxide wettable powder 500-fold spray can be used. For plots with severe rot on green onions, the diseased plants should be taken out of the field for burning or deep-buried treatment. Laminated lime should be sprayed around the diseased holes to prevent the spread of the disease.
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