Detailed Explanation of Apple Valsa Canker Prevention and Control Methods and Techniques

Apple Valsa canker is one of the more serious diseases affecting apple-producing areas in China. In the northern apple-producing regions of China, Valsa canker occurs very severely, with tree trunks covered in disease scars and branches and trunks incomplete, often causing tree death and orchard destruction, with a trend of worsening in recent years. Let's take a look below at the detailed explanation of apple Valsa canker prevention and control techniques!

I. Conditions for the onset of apple Valsa canker

Extensive cultivation management and freeze damage are the main triggers for Valsa canker epidemics. Orchards with low soil organic matter, compacted soil or poor water and fertilizer retention, poor root growth, insufficient compound fertilizer, excessive nitrogen fertilizer application, excessive fruiting, severe alternate bearing, and early defoliation that cause weakened tree vigor all have more severe disease incidence, while the opposite conditions result in milder disease. Orchards in low-lying areas with prolonged water accumulation in later stages, as well as those prone to late-season excessive vegetative growth, delayed dormancy, and thus susceptible to freeze damage, also have severe disease incidence. Periodic freeze damage in the north, causing large areas of bark freeze injury on tree trunks, is an important cause of widespread Valsa canker epidemics.

II. Apple Valsa canker prevention and control techniques

1. Strengthen cultivation management

Strong trees resist disease. Reasonable pruning, adjusting tree vigor, regulating tree load capacity, overcoming alternate bearing, increasing organic fertilizer application, rationally combining nitrogen, phosphorus, potassium fertilizers and medium and trace elements, doing a good job of cold protection for fruit trees, reducing freeze wounds. Bearing trees should be whitewashed. Common whitewash formula: lime:salt:water:animal oil (10:1:30-35:0.2). Generally carried out after fruit trees lose their leaves, with trunk coating height of 2 m.

2. Timely orchard sanitation

Timely orchard sanitation can reduce pathogens. When disease spots are found, scrape them off promptly. During pruning, pay attention to removing diseased branches, residual stubs, and diseased fruit spurs. Pruned diseased branches and dead diseased trees should be promptly removed and burned. Pruning and saw cuts and other wounds should be sealed with fungicides or paint to reduce pathogen infection pathways.

3. Use chemical prevention

Spray fungicides in early spring before tree buds break. Fungicides include Gerun or Shinaning aqueous solution at 500 times dilution, 3-5 degree lime sulfur mixture, 5% Jun Du Qing aqueous solution at 500 times dilution, etc. From June to July, the above fungicides can be used to brush large branches and trunks. Continuous prevention over several years has significant effects.

4. Use disease scar treatment

Scraping method: Cut a protective ring 0.5 cm beyond the edge of the disease scar with a knife, reaching deep into the xylem. Then thoroughly scrape off the diseased bark and healthy bark within the ring. Collect the diseased tissue scraped onto a plastic sheet and burn it. For the exposed xylem, use a knife to deeply cut 1-1.5 cm and then apply medication. Gerun at 5 times dilution, 5% Jun Du Qing aqueous solution at 5 times dilution, etc. can be used for smearing. Apply once more 20 days after treatment.

Mud compress method: Mix water and mud into mud cakes, apply to the disease scar and a 5-8 cm surrounding area, with a thickness of 3-4 cm. Then tie tightly with plastic sheeting or kraft paper. This method should be carried out in spring. Remove the wrapping in the following spring, clear the diseased residual tissue, and apply fungicide for disinfection and protection.

Foot grafting method: Using foot grafting (or bridge grafting) can improve the tree's ability to transport nutrients and water, which is beneficial for restoring tree vigor and can extend the fruiting years. This method is widely used in old fruit-producing areas and can be actively promoted in new fruit-producing areas.

The above is the introduction by Tuliu.com on apple Valsa canker prevention and control techniques. The occurrence of apple Valsa canker is closely related to tree vigor, number of wounds, wound-healing ability, etc. Extensive management and periodic freeze damage are the main epidemic factors.