Occurrence and prevention of pear scab

Pear scab is the main disease of pear trees, which occurs in the pear area of ​​our province. Especially in recent years, the pear area in the northern Hebei Plateau area is more seriously damaged. The pear area is generally susceptible, and the fruit disease is more than 80% . Declining and inferior quality have brought serious economic losses to fruit farmers. Some fruit farmers have lost their enthusiasm for fruitfulness and relaxed the management of existing pear orchards.

 

　　 1. Symptoms: This disease mainly affects leaves, fruits, buds, inflorescences, new shoots, petioles and fruit stems. After leaf sensation, there are round or unplanned pale yellow spots between the main veins of the leaf back and the branches, and the boundary is not obvious. After a few days, black mold powder appears. After the lesions are fused, the black mold layer is spread and the leaves gradually After the yellow detachment, the petiole and veins are damaged, black oval lesions appear and dents, resulting in black mold layer. After the fruit is damaged, the fruit surface produces light brown, round lesions, which gradually enlarge, and a large amount of black mold powder appears. In the depression, the cork is cracked. In severe cases, the fruit is deformed, the surface of the fruit is uneven, the flesh of the diseased part is soft, the bitterness is bitter, the fruit is easy to fall early, the fruit is damaged in the later stage, the fruit surface is dry and rough, but the mold layer is few. There is no deformity, the disease is mature, the surface of the fruit appears pale yellow lesions, the edges are not neat, most of them are awn-like, no mold layer, under the condition of high temperature and high humidity, the lesions expand rapidly. A large number of black mold layers appear, and the late stage of tree growth, the mildew layer is easily washed away by rain, the scale fluff is more, the mildew layer appears in the later stage, and the bud scale is cracked or even dead in severe cases. Every spring, the new shoots grow out at the base. Yellow, irregular lesions appear, and are quickly covered with black mold, called mold or mildew.

 

　　 2 , the infection cycle: the bacteria overwinter on the shoots, buds, leaves. When the pear tree sprout in spring, it rains or the temperature is slightly higher, the bacteria began to germinate infection, the incubation period of 20 days, to spend behind - when a layer of leaves (May) symptoms, infested leaves Young fruit has become a source of disease. In the case of rain and low temperature, spores spread a lot with the wind and rain. Due to the continuous germination of spores, multiple infections are formed. 7 - In August , when the average temperature exceeds 28c , the drought will be slow and the disease will slowly weaken or basically stop spreading. After the temperature is lowered, in case of rain or rainy weather, high temperature and high humidity occur, especially in harsh weather conditions, and the bacteria are repeatedly infested until October .

 

　　 3 , prevention and treatment:

 

Planting new disease-resistant varieties: In terms of long-term development, the promotion of planting new disease-resistant varieties is the most effective measure to comprehensively control pear black spot disease and reduce pesticide pollution.

 

Clean up the orchard: combine with winter pruning after defoliation, timely remove leaves, diseased fruit, weeds, dead buds, etc., deeply buried or taken out of the garden to burn, clearing the source of overwintering bacteria. On this basis, winter ploughing and winter irrigation are carried out at the same time to reduce the damage degree of pear black spot disease and ensure a good harvest in the coming year. Year 4 - May timely pruning diseased buds, shoot disease, diseased leaves, diseased fruits, centralized burned or buried to prevent the spread of germs to expand.

 

Strengthen cultivation. Management: To maintain the ventilation and light conditions of the pear garden and the strong tree, it can reduce the incidence. (1) Moderate close planting, planning tree shape. Practice has proved that the use of inverted human figures is happy, the plant spacing is 1 . 5 — 2mx4m ratio. It is more suitable to retain only 2 backbone branches , and evenly distributed the result branches on the backbone branches, the height of the tree is no more than 2m . Reasonable pruning to prevent the result part from moving outward, the tree is strong and weak, the external strength is weak, and the fruit quality is improved and the damage of the bacteria is reduced. (2) Reasonable load. According to the ratio of fruit to fruit, the ratio of leaf to fruit determines the amount of fruit left in the pear. For example, the ratio of fruit to fruit is 3 - 5 : l , and the ratio of leaf to fruit is 25 - 30 : 1 . The output of Shengguo dense plantation should be controlled at 2500--3000kg .

 

Pear fruit bagging: The selection of pear fruit quality special bag is one of the effective measures to isolate the infection and protect the fruit.

 

　　 4 , chemical control:

 

1 10 % Shigao 1500 times +0 . 6 % insect light 2000 times + odd core amino acid 500 times. 2 10 % Shigao +85 % Ethylene Phosphate 1200 times +1 % worm light 3000 times + Poly Candy 600 times. 3 10 % Shigao 1500 times +5 % Anfu 1500 times +1 . 8 % of the insects are 6000 times light . 4 10 % Shigao 1500 times +68 . 75 % DuPont Yi Bao 1500 times + 20 % fenpropathrin 1500 times + rare earth fertilizer king 500 times. 5 10 % Shigao 1500 times +40 % DuPont Fuxing 8000 times +24 . 5% + CA2000 1500 times the force Wick fruit UMBO 600 times. â‘¥ 10% Difenoconazole 1500 times 4000 times +43% +30% LECTRA good moth pyridaben 1500 times 0 + potassium dihydrogen phosphate. 3 % to 0 . 5 %. 7 green is guaranteed 400 times. The above agents are used interchangeably. The effect is better.

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