1. Field diagnosis: Garlic leaf spot disease only harms the leaves. In the early stages of diseased leaves, the needle-like yellowish-white dots gradually developed into immersed chlorotic spots. Afterwards, they expanded into oval-shaped or spindle-shaped depressions parallel to the veins. The center was yellow with reddish-brown edges and peripheral yellow. In a pandemic, lesions quickly spread to the ends of the leaves or several lesions healed contiguously, causing the leaves to wilted and yellow, and the garlic plant to die. When a single lesion expands to the leaf margin, the leaf breaks from the diseased part. When the humidity is high, the diseased part produces dark green moldy matter, and the severe disease field shows a dark green color withering. The pathogenic bacteria like cold and high humidity, spring high humidity, continuous cropping, too dense planting and partial application of nitrogen fertilizer in garlic fields are heavy.
2. The key to prevention and control:
1 Rational rotation for crop rotation, and rotation of crops other than onions.
2 selection of disease-resistant varieties.
3 timely sowing, reasonable close planting.
4 Do a good job of fertilizer and water management, apply basic fertilizer, timely top dressing, mainly organic fertilizer, increase phosphorus, potassium fertilizer and trace fertilizer. Groove system, drainage and drainage.
5 chemical control. In the early stage of disease, use 70% mancozeb WP 500 times, or 40% saponin WP 500 times, spray 7~10 days, depending on the condition, spray 2~3 times.
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