(1) Symptoms and symptoms The height of the seedlings starts at 10 to 15 cm, and it is most detrimental at the later stage of childbirth. The onset began at the tip of the leaf and spread to the lower part a few days later. It initially appeared slightly white with small spots. The center was slightly purple, and after expansion it was yellow-brown spindle-shaped or oval lesions. When the humidity was high, the diseased part produced black moldy appearance. Objects, lesions with multiple concentric ring pattern, easy to break from the disease department. Spread by air or rain. The onset temperature is 25°C～27°C, and the incidence is lower than 12°C. Generally, the onset is warm, rainy, or humid in the summer. It can be crushed on the onion garlic crop to spread the hazard.
(2) Prevention and cure method 1 Apply base fertilizer, strengthen field management, prevent waterlogging, and increase the host disease resistance.
2 Implement rotation for more than 2 years.
3 Use disease-free garlic seeds or sterilize with warm water at 40°C～45°C for 1.5 hours.
4 At the beginning of the disease, spray 75% chlorothalonil wettable powder 500-600 times, or 64% antivirus WP 500 times, 58% metalaxyl MnZn wettable powder 500 times, 50% acetaminophen Wettable powder 1500 times, every 7 to 10 days in a round of medication, continuous control of 3 to 4 times, have better results. In addition, spraying 0.003% of 2% polymycin wettable powder is effective.
5 timely harvest, reduce temperature and moisture, low temperature storage can prevent the disease continues to spread. Note that spraying should be stopped 7 to 10 days before harvesting.