Apple ring rot disease is one of the significant diseases affecting the branches and fruits of apple trees, with considerable impact on the growth and quality of apples. It is crucial to implement effective prevention and control measures. Let's explore the methods for preventing and controlling apple ring rot disease.
Symptoms of Apple Ring Rot Disease
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Branch Symptoms: Dark brown, water-stained, or small ulcerated spots form around the pores on the branches. They gradually sink and become concave, with raised edges and cracks, accompanied by sparse black dots. Multiple lesions cluster, causing rough bark on the main branches, hence termed "rough bark disease."
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Fruit Symptoms: Circular spots appear around the fruit points, initially light brown and later turning brown, forming concentric circular lesions with alternating light and dark colors. There are noticeable light-colored water stain rings on the outer edges. As the lesions expand, the fruits may rot, emitting a sour odor, and sometimes oozing brownish fluid.
Prevention and Control Methods
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Clean Orchard: Conduct two cleanings in spring and autumn to remove residual branches and fallen leaves from the orchard, which should be centrally burned or deeply buried to eliminate overwintering sources of pathogens. Additionally, timely thinning of crowded branches and low-hanging shoots and opening up the canopy to improve tree ventilation are essential.
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Enhanced Fertilization and Irrigation: Strengthen fertilizer and water management, apply organic fertilizers, and ensure a balanced ratio of nitrogen (N), phosphorus (P), and potassium (K) to avoid excessive nitrogen application.
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Spraying on Branches: Change the practice of only spraying leaves and fruits but not branches. During spraying, both leaves and branches should be treated to block the source of infection and reduce the incidence.
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Early Disease Prevention: Apply Bordeaux mixture in spring, followed by Bordeaux mixture paste to young trees and Bordeaux mixture spray to main branches in late June. This treatment, continued for three consecutive years, can eliminate ring rot pathogens lurking in the seedling stage. For mature trees, spray a high-concentration Bordeaux mixture solution after pruning: copper sulfate: hydrated lime: water = 1:2:120.
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Rational Use of Pesticides: Prevention and control of ring rot disease should primarily use Bordeaux mixture, alternating with protective and systemic pesticides. In addition to Bordeaux mixture, other pesticides such as 70% methyl thiophanate, 40% propiconazole, 10% fenbuconazole, and 2% diniconazole can be used during the growing season.
Above are the methods for preventing and controlling apple ring rot disease. This disease has a significant impact on apple trees and requires diligent prevention and control measures.
