Apple brown spot disease, also known as green-margined brown spot disease, mainly damages leaves, and can also infect fruits and petioles, leading to early leaf deciduousness. Among apple varieties, Hongyu, Fuji, Jinshuai, Wojin, Banana, Marshal, Guoguang and so on are susceptible to diseases.

The occurrence and prevalence of the disease are closely related to climate, cultivation, and varieties. In the years of continuous rainy summer, the onset is often early and severe, and rain is the main condition for the epidemic. In July and August, frequent rainfall and relatively high humidity, especially old orchard trees are closed, poor ventilation and light conditions, insufficient attention by farmers after bagging, and prolonged application intervals can aggravate the occurrence of apple brown spots. .

The brown spot pathogen overwinters on diseased leaves with mycelium and conidia discs, and produces conidia in the second spring, which is spread by wind and rain and infects directly or from stomata. The field can be reinfested many times. Generally, the onset begins in early and mid-June, and the peak period is from July to September. In severe cases, it can cause a large number of leaves to fall.

The disease first occurs in the middle and lower leaves of the tree, and gradually spreads outward. The prevention and control of brown spot disease should start with improving environmental conditions, strengthening field management, improving the ecological environment, insisting on focusing on prevention, supplemented by treatment, and comprehensive prevention and control to reduce harm.

1. Optimize the orchard environment and reduce disease conditions

In autumn and winter, completely remove the fallen leaves in the orchard, cut off the diseased branches and leaves on the tree, remove the dead fruits, and bury them in a concentrated manner or burn them; remove the diseased leaves, diseased fruits, and diseased tips during the growth period, eradicate the source of overwintering and oversummer bacteria, and reduce Base of incidence. The brown spot disease spreads directly 50 cm away. Prune the branches that are 50 or 60 cm above the ground. Reasonably dense planting, timely pruning and removing dense branches and leaves, improve ventilation and light conditions, and reduce orchard humidity.

2. Strengthen soil, fertilizer and water management

Reapply organic fertilizer, biological bacteria fertilizer, and increase phosphorus and potassium fertilizer to strengthen tree vigor and improve disease resistance. Avoid simply applying too much nitrogen fertilizer. Orchards with poor soil physical properties should be improved, and drainage facilities should be repaired in time to remove stagnant water and prevent the orchards from being too wet.

3. Chemical control

In the choice of medicaments, protective fungicides should be used before the onset and rain, and protective and therapeutic fungicides should be used after the onset and after the rain. For the prevention and treatment of brown spots, the interval between medications should be mastered, usually every 10-15 days. It is especially emphasized that if you encounter continuous rainfall, regardless of whether you have been sprayed before the rain, after the rain stops and the weather is clear, spray a fungicide in time.