Grasp the prevention and control of scallion blight in summer

In the hot, humid and rainy seasons of spring and summer, epidemic scallion blight is prone to breaking out, causing scallion leaves to droop and wilt, or even rot, resulting in serious losses, so related prevention and control work must be done well.

In the hot, humid and rainy seasons of summer, epidemic scallion blight is prone to breaking out, which can turn originally green scallions covered with yellow spots within a few days, then turning white, with leaves drooping and wilting, or even rotting, causing serious losses. Scallion blight mainly damages scallion leaves and flower stalks. In the early stage of infection, scallion leaves show indistinct pale greenish-white lesions, which after expansion become grayish-white spots, spreading longitudinally along the scallion leaves and quickly becoming long white spots whose width exceeds half the circumference of the scallion tube, or even larger; this causes the scallion leaves to droop and wither; during rainy periods or when humidity is high, white cottony mold grows on the diseased parts; when the weather is dry, the white mold disappears, but tearing open the diseased leaves still reveals cottony white mycelium on the inner side of the scallion tube leaves. In summer, the prevention and control work for this disease must be done well:

1. Cultivate on high beds with deep furrows, dig ditches for drainage, reduce humidity, and drain water promptly on rainy days to lower field humidity.

2. Spray foliar fertilizer appropriately and timely, increase phosphorus and potassium fertilizer and trace element fertilizer, avoid over-application of nitrogen fertilizer; applying plant ash is also helpful for improving disease resistance;

3. According to weather changes, spray pesticide promptly for control. Use 25% Ribang Kejun at 1000 times dilution or 25% metalaxyl mancozeb at 600 times dilution, spraying 2 to 3 times, once every 7 to 10 days. Spraying must be comprehensive and thorough, wetting and soaking the plants.

4. Severely diseased plants in the field must be thoroughly removed and destroyed to prevent the spread of the disease.