Integrated control of garlic leaf blight

Allium sativum L. (Garlic) belongs to the genus Allium of Liliaceae, which is used as medicine in bulbs. Harvesting in spring and summer, tying, hanging in ventilated place, drying in the shade for later use. In June, when the leaves are dry, dig, remove sediment, ventilate and dry or bake until the outer skin is dry. Garlic is flat spherical or short conical, with gray or light brown membranous scales outside, stripped of scales, 6~10 garlic petals inside, born around the flower stem, disk-shaped at the base of the stem, with many fibrous roots. Each garlic cloves wrapped in thin film, stripped of thin film, that is, white, plump and juicy scales. It has a strong garlic smell and a spicy taste.

Plant form of garlic

Herbs perennial, with a strong garlic odor. Bulbs large, 6 - 10-merous, surrounded by gray-white or lilac membranous scales. Leaves basal, solid, flat, linear-lanceolate, ca. 2.5 cm wide, base sheath-like. Floral stems erect, ca. 60 cm high; spathes long beaked, 7 - 10 cm long; umbels small and dense, with 1 - 3 bracts, 8 - 10 cm long, membranous, light green; flowers small, intermingled with reddish bulbils, 4 mm long, or completely absent; pedicels thin, longer than flowers; perianth 6, pink, elliptic-lanceolate; stamens 6, white, anthers prominent; Pistil 1, style prominent, white, ovary superior, oblong ovate, apex concave, 3-loculed. Capsule, 1-loculed. The seeds are black. Summer flowering.

Integrated control of garlic leaf blight

Garlic leaf blight is one of the common diseases on garlic. It occurs in different vegetable areas and mainly damages garlic cultivated in open field. Garlic growth period precipitation times more, rainfall years heavy disease. Serious disease often causes disease leaves to die, plant premature aging, garlic yield reduction, garlic moss mildew, directly affect the yield.

Characteristics of garlic leaf blight

White dots at first, irregular or oval gray or brown spots after expansion, black mold on the head, many black particles scattered on the head. When the damage is serious, the whole plant will not sprout.

Pathogenesis of garlic leaf blight

This disease is caused by Pleospora herbarum (Pers.ex Fr.) Rabenk infection. In spring sowing garlic cultivation area, the pathogen overwintered mainly in the form of mycelium or ascocarp left behind by the diseased body, produced ascospores in the next year to cause initial infection, and produced conidia in the later diseased part to re-infect with airflow and raindrop splash. After emergence of autumn sowing garlic, conidia produced on the diseased body spread with airflow and raindrop splash and landed on garlic leaves, causing infection and disease. The fungus is a weak parasitic fungus, often accompanied by downy mildew or purple spot mixed occurrence. Pathogens are more adaptable to temperature, but they need higher humidity. Rainfall and high humidity in the field are necessary conditions for disease epidemic. The peak period of garlic leaf blight in Zhejiang and the middle and lower reaches of Yangtze River was in plum rain season. The susceptible growth period of garlic is in the mature stage. Generally, the disease is serious in low-lying fields, poor drainage, partial application of nitrogen fertilizer, mixed cultivation of onion and garlic vegetables, plant injury, thin plant growth and continuous cropping. The incidence is heavy in rainy season or foggy and rainy year in autumn.

Comprehensive control methods of garlic leaf blight:

1. Seed disinfection. Soak seeds in warm water at 50℃ for 30 minutes before sowing or dress seeds with 0.5% ammonium bromide and thiram to disinfect seeds. 2. Soil treatment: soil disinfection can be carried out by mixing thiram and pentachloronitrobenzene 1:1, 500-750 grams per mu, mixing with 400 times dry soil, and spreading soil surface before ploughing.

2. Trenching to remove moisture. The sowing period of early-maturing garlic is from September to October, which is in the late rainy season. The soil is wet, easy to rot and die seedlings and induce the occurrence of garlic leaf blight. Especially in rice stubble fields, ditch drainage should be carried out to reduce soil moisture, which is conducive to seedling emergence and reduce pests and weeds.

3. Increase fertilizer application. Garlic fibrous root less, absorption is weak, it needs loose soil and rich organic matter. Advocate to give priority to with farmyard manure, increase apply phosphor, potash fertilizer. Through fertility, improve plant disease resistance.

4. Chemical control. At the initial stage of disease, 70% mancozeb can be sprayed at 200g per mu, and then prevented once every 7-10 days; at the peak of disease, 50% iprohydantoin wettable powder 1500 times solution or 50g per mu can be used for prevention and control, or chlorothalonil, manganese zinc and other broad-spectrum pesticides can be used for prevention and control.