First, root rot
1. The condition. Astragalus root rot mainly damages the roots. Branch roots and fibrous roots in the early stages of disease begin to turn brown and rot, and then gradually spread to the entire roots, rot, and the whole plant dies.
2. The law of occurrence. The disease is a fungal disease. The pathogen is the fungus Fusarium solani, a fungus which is a kind of soil habituating bacteria. The mycelia, chlamydospore, and sclerotium adhere to the sick tissue in the soil in winter. When conditions are favorable, conidiospores or zoospores are produced to reproduce, invade the host's wound to form a primary infection, and spread through the water stream or soil to cause re-infestation. When the weather is fine, rain, high temperature and high humidity, poor plant growth, frequent underground pest activity, soil viscosity, poor drainage, and application of unrefined manure can aggravate the disease.
3. Control measures. (1) Agricultural control. Increase phosphorus and potassium fertilizers; timely drainage and flood control in the rainy season; timely removal of diseased plants. The crops with recurrence of root rot and oil sunflower, beans and other crops will be rotated for more than three years. (2) Chemical control. At the beginning of the disease, spray with 50% carbendazim WP 1000 times, spray once every 7-10 days, use 2-3 times; spray 80% Guanlong-21 WP 1500 times, or use 50% thiophanate-methyl 1000-fold watered diseased plants.
Second, stem rot
1. The condition. Scutellaria baicalensis stem rot mainly damages the stem base and the main root of large seedlings or adult plants. The diseased department was dark brown at the beginning and spread around the base or root of the stem. As a result, the cortex rotted and the leaves of the shoot turned yellow, causing the plant to die. In the later stages of the disease, dark brown sclerotia of different sizes can be formed on the surface.
2. The law of occurrence. The disease is a kind of fungal disease. The pathogen is R. solani sclerotiorum, which is a soil habitation bacterium, and has a strong saprophytic ability. The sclerotia mainly live in the soil in winter. When the spring conditions are appropriate in the second year, the sclerotia will invade the silk and cause the disease from the wound or tender skin to invade the base of the stem or stem. The disease can spread through mycelium propagation, weeding, and weeding in close quarters. It can be transmitted through long-distance soil and unfermented manure with mycelium and sclerotia. The bacteria can infect at 13-42°C, and it is conducive to infection at a high humidity of around 24°C. Lack of fertilizer and water, weak plant growth, and more wounds are also conducive to disease.
3. Control measures. (1) Agricultural control. Serious diseased fields should be rotated for more than 3 years, and it should be the best for rice rotation; after the autumn, the diseased bodies should be promptly removed; the formula fertilization should be applied, and weeding should be avoided when weeding; the underground pests and root nematodes should be controlled in time to prevent the transmission of diseases. (2) Chemical control. In the initial stage of illness, spray 50% wettable powder 1000 times, or 50% acetaminophen 1000 times spray the base of the stem, and then spray again 10 days later.
Third, leaf blight
1. The condition. Jaundice leaf blight mainly damages the leaves. Symptoms are irregular black-brown lesions that extend inward from the tips of the leaves or leaves, spreading rapidly from top to bottom, causing the leaves to die.
2. The law of occurrence. The pathogen is a fungus in fungi. The fungus overwintered on diseased leaves, and when the temperature was appropriate in the following year, the spores of the pathogen spread to the host plants through the wind and rain, and the disease of the lower leaves of the plants was heavy. Severe onset in high temperatures and rainy seasons, the incidence of weak plant growth is more serious.
3. Control measures. (1) Agricultural control. In winter, the diseased plants are treated and the diseased plants infected with the diseased bacteria are uprooted and burned to eliminate the overwintering germs. (2) Chemical control. At the beginning of the disease, use 50% carbendazim WP, 1000 times liquid 1:1 12020 Bordeaux spray, spray once every 7-10 days, 2-3 times in succession.
Fourth, powdery mildew
1. Symptoms. Astragalus membranaceus mainly damages the leaves and pods. White spots appear on both sides of the leaves. It seems to be sprinkled with a layer of white powder. The lesions converge and cover the entire leaf. Finally, black spots are scattered on the lesions. When the humidity in the field is large, it is easy. Onset, leading to early dryness or poorly solid or even not strong.
2. The law of occurrence. The pathogen of this disease is Erysiphe graminicola. The pathogenic bacteria overwintered the mycelia and the closed capsule on the residue of jaundice and became the initial infection source in the following year. When the environmental conditions are appropriate in late May, conidiospores are generated on the wintering hyphae and the ascospores are released from the closed capsular shell. The infection is transmitted along with airflow, rain, etc., causing the disease. Subsequently, conidia were infested several times, and in late September, the closed cyst shells developed over winter with the diseased body.
3. Control measures. (1) Agricultural control. Strengthen field management, timely removal of diseased bodies in autumn and winter can reduce the winter fungus, pay attention to the air ventilation. (2) Chemical control. In the early stage of the disease, spray 40% fluorosiliconazole suspension 10,000 times and 12.5% ​​Shixingxing WP 500 times, 2-3 times.
Fifth, gray mold
1. Symptoms. Symptoms of Botrytis cinerea are classified into two types: common type and stalk-based rot type, with stalk-based rot being the most dangerous. The common type mainly damages the young leaves, tender stems, flowers and tender pods of Astragalus membranaceus, and forms near-circular or unplanned, brown or dark brown lesions. The lesions on the leaves easily start from the tips of the leaves and leaves, and gradually expand inwards. Lesions usually have obvious ring patterns. When the humidity is high, each diseased part has a gray mold layer, and later lesions expand, which can cause dry leaves of the whole leaf and fruit can not be necrotic. Stem-based rot mainly occurs on 2-3-year-old jaundice and can occur on a single scale; this type of disease is early onset and usually occurs after 2-3 years of growth and development of Astragalus membranaceus, which mainly affects the roots of the scutellaria about 10 cm above and below the stem base. Due to the low incidence of disease sites and sheltered by the stems and leaves on the ground, the locally high microclimate humidity is very conducive to the infection of pathogens. After a week of ring disease, the diseased part produces a large number of gray mold layers, and the stems and leaves immediately Withered; a cluster of astragalus has one or several stem bases that have been infected, and often quickly spread to other stem bases, resulting in the majority of a cluster of jaundice that die of disease.
2. The law of occurrence. The pathogen of Botrytis cinerea was Botrytis cinerea. The pathogenic bacteria used mycelia or conidia to overwinter on the residue of Jaundice or sclerotium in the soil and became the initial infestation source in the following year. Afterwards, conidiospores were re-infected several times with air flow, rain, etc.
3. Control measures. (1) Agricultural control. The timely removal of diseased bodies in winter and autumn can reduce overwintering bacteria. (2) Chemical control. In the early stage of disease, spray 70% of Botrytis cinerea wet powder 60 g/mu, 50% of chloramphenicol WP 100 g/mu, spraying 2-3 times.
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