Comprehensive Control Measures for Non-pollution of Downy Mildew in Chinese Cabbage
I. Symptoms Cabbage downy mildew is commonly known as "baking disease", "running horse", "dry leaf", "white mold", "mist disease", etc. It is very harmful to Chinese cabbage, mainly harming the leaves, followed by stem, pedicel, and seedlings. pod. The incidence of cabbage seedling stage, at the beginning of the leaves on the back of the white layer of frost-like mold, the front of the leaf no obvious symptoms, severe seedlings and stems become yellow withered. Plants were killed, and white downy mildew was observed on the leaves. The leaves showed light green lesions on the front and gradually turned yellow to yellow-brown. Lesion enlargement is often limited by the veins to form a polygonal shape. After the Chinese cabbage enters the heart-filling period, if the environmental conditions are suitable, the disease develops rapidly and the lesion rapidly increases, causing the dead leaves to die, from the outer leaves of the plants to the inner leaves, the layers are dry, and only one leaf ball remains. When the wind blows leaves or pedestrians move around inside the cabbage field, they become "white smoke." The stems, peduncles, and seed pods of the plant were found to be infected with fungal pathogens, and the growth was too prosperous. Such as concurrent white rust, the stem and pedicel swollen bent deformity is more obvious, commonly known as the "agriculturist". The victims were twisted and twisted, and the surface was dark brown and brown and necrotic, resulting in unreal or semi-real fruits. When the humidity is high, the symptoms of the diseased fruit, stem, and pedicel are also white.
Second, the law of pathogenic bacteria with the disease in the soil, or leave the plant strains, or attached to the seeds on the winter, by wind and rain, repeated reinfection. The formation of sporangia requires water droplets or dew, and thus the disease is susceptible to epidemics even in rainy weather, high air humidity, or long duration of condensation. The average annual minimum temperature is heavy and the disease is heavy. Early onset of sowing, defertilization, or heavy virus disease, etc., are severe.
Third, control methods
1 It is very important to use disease-resistant varieties. Sometimes the two varieties are planted in the same vegetable field, and the susceptible varieties are messy, while the disease-resistant varieties are not serious. Xia Dongqing, Chongbai, Beijing No. 106, Zhongbai, Shuangguan, Qingqing, Yubai No. 1, Beijing No. 4, No. 26, No. 88, No. 100, Qingyan 169, Shuangqing 156, Chengyangqing, Tianjin Qingmaye, Kaiyuan Cabbage, Yuejin No. 1, and Qingmao Leaf Line 816-812 were resistant to downy mildew.
2 Proper sowing practice has proved that early sowing is more serious than late sowing, but late sowing often affects the heart and reduces the yield. Therefore, proper sowing should be done according to the local climate. For example, the suburbs in Beijing are suitable for planting from August 3rd to the 7th.
3 Reforming planting methods The southern region generally adopts deep ditch sorghum cultivation, while the north generally adopts belt-like and equal spacing planting. In the suburbs of Beijing, reforms have been carried out in a wide-narrow manner and have been used to fight drugs. They have received good results. It is also convenient for the company to keep the fight against drugs and prevent the disease and ventilation of the cabbage after ridge sealing. The "six-for-one" or "four-for-one" wide and narrow lines can be used, which not only has good disease prevention effect, but also avoids damage to cabbage caused by the spraying operation.
4 to strengthen water and fertilizer management to apply the base fertilizer, increase phosphorus, potassium fertilizer. Early seedlings, Dingmiao late, moderate seedlings. Small water ground irrigation, timely drainage after rain. During the rosette period, it is mainly to promote growth, timely watering, to meet the water required for its growth, before and during the middle period, it can be sprayed with phytoalexin 6000 to 9000 times liquid or sugar urine (Brown sugar: urea:water=1:4 :100, spray in the morning, spray on the back of the leaves, can increase plant resistance to disease. At the same time, the watering topdressing is strengthened to make the cabbage early in the morning and prevent premature aging.
5 The incidence of clean seedlings in the pastoral period should be eliminated when the seedlings and the seedlings are seedlings, and the diseased leaves and diseased plants should be cleared out or burned out of the fields after deep-rooting and deep-turning the soil to reduce the spread of germs in the fields.
6 In the early stage of disease prevention and cure, 72% of Ryokon WP can be used 800 times, or 65% of Po Omson WP 800 times, or 72.2% of Proplohydrate 600 times, or 78% of Cobo WP 500 Diluent, or 56% wet down wettable powder 700 times, or 69% ank manganese zinc wettable powder 600 times, or 50% methyl copper wettable powder 600 times, or 90% of the milk cream can be Wet powder 500 times, or 70% acetomanganese wettable powder 400 times, 72% kemycin wettable powder 500 times, or 72% gel wettable powder 700 times, 72% Keling wettable powder 60 times liquid, or 50% Anke wettable powder 1500 times, or 58% Methanomanganese WP wettable powder 500 times, 72.2% Proplohydrate, 600 times liquid, 52.5% fast water dispersion particles Agent 1500 times, 64% antiviral M 8 WP 600 times, or 90% ethoxyphosh WP 800 times potassium permanganate 1000 times, or 25% metalaxyl WP 800 times Liquid, or 58% metalaxyl MnZn wettable powder 500 times, or 72% cream urea manganese zinc wettable powder 1200 times, or 70% mancozeb WP wettable powder 500 times liquid spray, each 6 to 8 days spray 1, spray a total of 2 to 3 times.
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