Identification and Prevention of Common Maize Diseases

Maize big spot disease damage symptoms: corn leaf spot mainly damage the leaves, but also seriously damage the leaf sheath and temporal lobe. The disease begins with the lower leaves of the plant and expands upward. The lesions are long spindle-shaped, gray-brown or tan-colored, 5-10 cm long and 1 cm wide. Some lesions are larger, or several lesions are connected to a large, irregular spot, and the leaves are in a state of severe coking. Rainy and wet weather, dense gray mold layer can be densely stained. In addition, there is a lesion that occurs on disease-resistant varieties, spreading along the veins, showing a brown necrotic streak, surrounded by yellow or light brown chlorotic circles, with no spores or very few spores. Control methods: selection of anti-resistant varieties, intensify cultivation and management, re-application of pesticides and Other comprehensive measures. 1. Selection of resistant varieties and maize hybrids resistant to spot disease. 2. Implement the rotation system and the collapse system. Avoid continuous cropping of corn, deep-fall soil in autumn, deep-fall diseased plants, eliminate sterilization sources, use corn stalks as fuel, treat them as soon as possible after the beginning of spring, and simultaneously treat corn borer; fully compost the diseased body as compost, most of straw fertilizer Do not apply in corn fields. 3. Improve cultivation techniques and enhance corn disease resistance. Early sowing of summer maize can reduce the incidence; interplanting with wheat, peanut, sweet potato, and wide and narrow row planting; rational irrigation, pay attention to field drainage. 4. Spray control. Before and after corn tasseling, the disease rate in the field reached more than 70%. When the diseased leaf rate was 20%, spraying was started. Anti-effective agents are: 50% carbendazim WP, 50% amifenzin WP, 90% mancozeb, all 500 times more water, or 40% EKS 800 times spray. 50-75 kilograms of liquid per acre, sprayed once every 7-10 days, total control 2-3 times. Commonly used pharmaceuticals: carbendazim, diazepam, mancozebite, and potassium oxime. Symptoms of corn borer damage: corn borer clustered in the heart of the corn seedlings, sucking damage. As the plant growth is concentrated on the newly born leaves, it is harmed. Most of the booting stage is concentrated in the flag leaves and leaf sheaths. While sucking the corn sap, it excretes a lot of honeydew, covering the foliage of the honeydew on the leaf surface affects the photosynthesis, easily causing mold parasites, the victim plants grow weak, stunting, yield decline . Control methods: 1. Agricultural control (1) Eradication of weeds in the field to reduce the source of insects; (2) Pull out the tassels of the central buds to reduce the amount of insects; 2. Chemical control application of granules. Use 40% dimethoate 50 ml, dilute 0.5 kg, mix 15 kg of sand, and sprinkle 1 g per mu. With 50% anti-inferiority WP, 6-10 grams per acre, watered 60-75 kg spray, or 40% omethoate EC 50 ml, add water 50-75 kg. Use 75 kg per mu. Commonly used pharmaceuticals: Dimethoate, Omethoate, Anti-Kaiwei, 10% Dagong Chen WP. Symptoms of corn borer damage: Corn borer is larvae. The instar larvae feed on young leaves to form rows of holes. After 3rd instar larvae invaded the stalks, it injure the scapes, tassels and ears. The nutrition and moisture transmission of the damaged corn are obstructed, the growth is weak, the stalks are easy to fold, the ear development is poor, and the effects are strong. The larvae infested the cotton into the tender stems, causing the upper part to die, and eating bolls caused ringing, rot and deadlock. Control methods: 1. Agricultural control treatment of wintering host stalks is completed before spring larvae larvae and eclosion. 2. Chemical control (1) In the late spring period of the heart of the corn, the general rule is to apply the 10% of the mosaic. The leaf mosaic rate in the middle of the heart exceeds 20%, or 100 eggs and 30 eggs or more are accumulated, and it needs to be prevented again. (2) Summer corn is controlled once at the end of the heart. When the panicle rate at the ear stage is 10% or 100%, there are 50 insects in the ear, and it is necessary to prevent and treat it immediately. (3) Gutian needs prevention and treatment when there are more than 5 eggs per 1000 grain seedlings. The granules can be used as granules, with 50% parathion EC 500 ml plus appropriate amount of water, and 25 kg sieved (25-60 mesh) of cinder or sand granules. Corn locules applied 1-2 grams of granules per plant at the end of the season, and insecticidal double or hydrogen bromide, or monocrotophos could be used. 3. Biological Control (1) The release of Trichogramma, from the beginning of spawning to the end of spawning, releases Trichogramma 2–3, releasing 1–20000 heads per acre. (2) Using Bt emulsion, use 200 ml per gram of emulsion containing more than 100 spores per acre, mix it with granules or mix spray with agent. (3) Use Beauveria bassiana to seal the alfalfa, and use 100 grams of germ powder per cubic meter of straw (with 50-100 million spores per gram) to spray on the alfalfa before the corn pupa. Common agents: parathion, dimehypo, bromide, 4000 IU/μl suspension of Bacillus thuringiensis, 8000 IU/μl suspension of Bacillus thuringiensis. Source: Modern Rural News

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