How to prevent and control gummosis in cherry trees? Growers need to master these methods

Symptoms

Gummosis is an important disease of cherry trees, and its symptoms fall into two types: dry rot type and canker type gummosis. The dry rot type mostly occurs on the trunk and main branches. In the early stage, the lesions are irregular, dark brown, and hard on the surface, often causing gumming. In the later stage, the lesions become elongated, dry-shrunken and sunken, sometimes with cracking around them, and densely covered with small black dots on the surface. In canker type gummosis, resin is produced in the diseased part of the tree, but it does not flow out immediately; instead, it remains between the xylem and phloem. The diseased part bulges slightly, and as the sap flows, it exudes from the lenticels or wounds in the diseased part. The diseased part is initially colorless and slightly transparent or dark brown, and hard.

Causes

Dry rot type gummosis is caused by Botryosphaeria dothidea (Phyllosticta? Camellia? Botryosphaeria) in the Ascomycota, and its conidia and ascospores are spread by wind and rain. It can infect from April to October, mostly invading through wounds, and is more severe in the early stage. This fungus is a weak parasite and can only infect weakened trees and weak branches. The weaker the tree vigor, the more severe the disease.

Canker type gummosis is caused by Botryosphaeria dothidea in the Ascomycota. This fungus is a weak parasite and has the characteristic of latent infection. After infection by the pathogen, resin is produced in the diseased part of the tree, but it does not flow out immediately; instead, it remains between the xylem and phloem. The diseased part bulges slightly, and as the sap flows, it exudes from the lenticels or wounds in the diseased part. The diseased part is initially colorless and slightly transparent or dark brown, and later becomes black-brown and hard. Wounds on branches and trunks caused by insect pests, freezing injury, sunscald and other mechanical damage are important entry points for the pathogen. Conidia are spread by rainwater. Gumming begins at the diseased part when sap flows in spring, and the disease gradually worsens after early June, being most severe in the rainy season.

Prevention and Control

1. In autumn and winter, apply more fully decomposed organic fertilizer to strengthen tree vigor, improve disease resistance, and prevent pathogen invasion.

2. Collect dead and diseased branches and trunks and burn them in a centralized manner or bury them deeply, and control trunk-boring pests to reduce sources of infection and wounds.

3. Scrape and treat lesions. The lesions are limited to the surface layer. In winter or after rain and snow in early spring, when the gum is relatively soft, scrape them off promptly with a sickle. At the same time, apply 402 disease-resistant agent at 50 times dilution or asomate at 50 times dilution to the wounds, then apply Bordeaux mixture paste for protection; or directly apply 5-degree lime sulfur mixture for control.

4. In severely affected orchards, before bud break, spray 40% asomate wettable powder at 100 times dilution, and during the growing season, combine with the control of other diseases and spray the branches and trunks for protection.