Shed leeks are an important seasonal food for urban and rural residents. However, they are vulnerable to gray mold, diseases, and sclerotinia in the cultivation process. Lighter production and severe harvesting are the biggest obstacles to the cultivation of leeks in greenhouses. First, gray mold 1. Symptoms: The main damage leaves, divided into white point type, dry tip type and wet rot type. (1) White spots and dry tips form white or light gray brown on the front or back of the leaves, resulting in scorching of whole or half leaves. (2) The wet rot occurs when the humidity is high. The surface of the dead leaves is densely gray to green and hairy, with a turbid smell of soil and no white spots on the leaves. (3) The dry tip type rots from the cut edge of the cutting blade and becomes light green after the initial water stain, with brown ring patterns. After the lesion spreads, it is semi-circular and forms a “V†shape. And can be extended down 2 ~ 3cm, yellow-brown, high humidity, the surface of gray brown or gray green hairy mildew. 2. The pathogenic bacteria of the onset of disease overwintered with the diseased body in the soil and on the diseased plants, and was initially infested and re-inflicted with airflow, irrigation, and rainwater. The disease has a close relationship with temperature and humidity. The temperature range for the growth of the bacteria is 25-30°C, and the optimum temperature for mycelia growth is 15-21°C. Spore germination requires water droplets or more than 95% relative humidity. Generally, the relative humidity is more than 85%, and the incidence is heavy. If less than 60%, the incidence is low or not. Therefore, under conditions of high temperature and high humidity, on the one hand, it is beneficial to the growth, reproduction and infestation of pathogenic bacteria. On the other hand, as chives grow fast, the disease resistance is poor, and the incidence becomes worse. 3. Control methods (1) Agricultural control: plant disease-resistant varieties; apply sufficient organic fertilizer; according to weather conditions, open a certain amount of greenhouse film ventilation at noon, reduce the humidity, so that the relative humidity within the shed is kept below 75%, but it is strictly prohibited Bottom wind. After the leek is harvested, the sick body shall be promptly removed, and the diseased leaves and diseased plants shall be buried deep outside the shed or burned to prevent the spread of germs. (2) Chemical control: spray 1% of agricultural anti-120 melon vegetable tobacco or 70% carbendazim or 70% thiophanate-methyl wettable powder before spraying each soil, spray 2 or 3 times, and the effect is very good. it is good. Focus on spraying the surface of the soil around the newborn leaves. Second, the disease 1. Symptoms: Roots, stems, leaves, flowers and mosses can be affected, especially in pseudostems and bulbs. Leaf disease mostly begins in the middle and lower parts. It appears as dark green water stains. It is 5-20 mm long and sometimes expands to half of the leaves. After the disease department loses water, it shrinks obviously, causing leaf and flower moss to droop and rot. When the humidity is high, The disease department sparse white mold. After the pseudo-stem was victimized, it was a water-stained, light-brown, soft rot, and the leaf sheath was easy to fall off. When humidity is high, white sparse mold layer grows on it. Bulb damage, the roots were water-stained, light brown to dark brown rot, longitudinal bulb light brown tissue, growth inhibition, new leaves thin. Root lesions brown rot, root hair reduction. 2. Incidence of disease: The pathogens overwinter with the diseased body in the soil. When the conditions are appropriate, sporocysts are released to release zoospores and infect the parasites. They are transmitted through wind and rain and water, and are repeatedly infested. High temperature (25 ~ 30 °C) high humidity (relative humidity above 95%) is an important condition for the disease. 3. Prevention (1) Agricultural control: crop rotation and continuous cropping; increasing organic manure, phosphorus and potassium fertilizers to improve plant immunity against disease. (2) Chemical control: Before or at the beginning of the disease, spray 4% agricultural anti-120 melon vegetable tobacco type 500-600 times or 50% amafrost copper wettable powder 600 times solution, spray 2 or 3 times. Third, Sclerotinia disease 1. Symptoms: The main damage to the leaves, leaf sheaths or stems. The damaged leaves, leaf sheaths, or bases of stems turn brown or grayish brown and rot and decay. In the diseased part, the cotton-wool hyphae were entangled and yellow-white to yellow-brown rapeseed sclerotia formed by the hyphae. 2. Incidence regularity: Rainy seasons or seasons are prone to onset. In addition, the terrain is low, drainage is poor, the density is too high, and partial application of nitrogenous fertilizers is prone to disease. 3. Control methods (1) Agricultural control: Prevent water accumulation; properly plant dense plants; avoid partial application of nitrogen fertilizer and increase application of phosphorus and potassium fertilizers. (2) Chemical control: Spray 500 to 600 times of 4% agricultural anti-120 melon vegetable tobacco solution in time after each harvest, spray once every 10 to 15 days, and spray 2 to 3 times, which can effectively prevent sclerotia The occurrence of the disease.
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