Pear black spot disease, the disease is mainly harmful leaves, fruits and new shoots. Young leaves develop, produce dark brown round spots, and then gradually enlarge, forming nearly round or irregular shaped lesions, the center is gray-brown, the edges are dark brown, the diseased leaves are scorched, deformed, and fall early. At the beginning of fruit damage, one to several black spots appeared on the fruit surface, which gradually expanded to form a gray-brown round lesion, which was slightly sunken, deformed and cracked in the later stage, causing fruit drop. The incidence of new shoots, the formation of dark brown oval lesions, slightly depressed, easy to break.
How to prevent and cure pear black spot disease?
First, the law of occurrence
The pathogens overwinter with conidia and mycelium on the affected shoots, diseased leaves, diseased fruits and diseased bodies that land on the ground. In the second year, conidia were produced in the spring and spread by wind and rain, causing initial infection from stomata, lenticels and direct invasion of host tissues. After the initial infection, the pathogen can cause reinfection in the field. Generally, the onset of the disease begins in late April, and the young leaves are extremely vulnerable. If it is rainy from June to July, it is more popular. The low-lying terrain, partial application of chemical fertilizers or fertilizers, unreasonable pruning, debilitating tree and unfavorable factors such as pear net mites and mites mites can aggravate the epidemic.
Second, prevention and treatment methods
(1) Strengthen the cultivation management of orchards:
Rational fertilization, re-application of base fertilizer, application of high-quality decomposed organic fertilizer, application of phosphorus and potassium fertilizer, timely supplementation of medium and trace element fertilizers, enhance tree potential and improve disease resistance. The tree is reasonably loaded. The orchard drains in time during the rainy season.
(2) Clearing the source of overwintering bacteria:
In the winter, when the pruning is carried out, the diseased branches are cut off, and the fallen leaves and fallen fruits in the garden are removed, and the orchards are taken out together to burn and bury.
(3) Chemical control:
Implement the principle of “prevention first, comprehensive prevention†and rationally choose pharmaceuticals.
1 After the winter cut, spray the Bamei 3-5 degree stone sulfur mixture liquid in time to clear the garden.
2 long-term medication: from the beginning of May can start the first spray, interval 15-20 days, even spray 3-5 times. 50% chlorhexidine WP 1000-1500 times solution, 75% chlorothalonil WP 1000 times solution, 50% carbendazim WP 800-1000 times solution, 70% thiophanate-methyl WP 1000-1500 times liquid and other drugs are used interchangeably.
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