Symptom Identification and Control Techniques for Sweet Cherry Gummosis (Dried Rot Disease)

Sweet cherry is a fruit with relatively high nutritional value, and even at a high price it is deeply loved by consumers. Many people purchase sweet cherries by the box. There are many key points in sweet cherry planting and management, and it is also prone to attacks by pests and diseases, so what are the symptoms of sweet cherry suffering from dried rot disease? Attached control techniques.

I. What are the symptoms of sweet cherry suffering from dried rot disease?

Dried rot disease is mainly caused by the fungus Valsa leucostoma (the black rot shell fungus of stone fruits), damaging the trunk and main branches, causing the bark to rot (not the outer skin), leading to withered branches and dead trees. It occurs from early spring to late autumn, with the most severe incidence from April to June, especially in the early fruiting stage. In the early stage, the cortex of the diseased part swells slightly and takes on a purplish-red tinge, with some parts showing slight gumming, and finally turns brown and dies, giving off a smell of distiller's grains, with small black raised granules appearing on the surface.

The pathogen overwinters in the trunk tissues as mycelium, perithecia and conidia, and spreads the following year from March to April via wind, rain and insects, invading through wounds and lenticels. April to June is the peak period, it is suppressed in the hot July to August period, and stops occurring after November. Improper fertilization (such as continuous application of undecomposed farmyard manure, chicken manure and pig urine) and rainy autumns, along with low cold resistance of the tree, can cause the disease. This is also why there are more withered branches and dead forks during the fruiting period and the phenomenon gradually eases after the fruit is harvested.

II. Control techniques for sweet cherry suffering from dried rot disease

1. Cultivate strong seedlings. In the nursery it is not advisable to use excessive water and fertilizer, and especially not to force seedlings with quick-acting nitrogen fertilizer, to prevent the seedlings from growing too vigorously and being prone to frost damage and then disease.

2. When planting, select robust seedlings and apply sufficient base fertilizer. The planting depth should be such that the graft union is level with the ground. After planting, irrigate promptly and strengthen management to shorten the seedling recovery period as much as possible. When transporting young trees, try to avoid causing wounds and dehydration. If wounds appear, disinfect with 1% copper sulfate solution or protect with lead oil to reduce the chance of pathogen infection.

3. Strengthen soil, fertilizer and water management. Apply more organic fertilizer and deep-plow to improve the soil; improve drainage and irrigation conditions so that irrigation is possible in drought and drainage is possible in rain; protect the tree body well to prevent frost damage; in addition, during field management operations, try to avoid various mechanical wounds to prevent inducing disease.

4. In the dormant period of the fruiting orchard, in combination with pruning and orchard cleaning, cut off and destroy all kinds of diseased, pest-infested or withered branches.

5. Scrape and treat disease spots as early and thoroughly as possible. Try to scrape and treat them in the early stage of the disease. March each year and the period around it is the best time to find and scrape and treat branch and trunk diseases. When abnormal parts or obvious diseased parts are found on branches or trunks, cut them off with a sharp knife, then disinfect with chemicals and protect with chemicals several times. For disinfection or protection chemicals, any of the following can be used for brushing: 3 times Fubiqing, Shukang stock solution, 10 degrees Baume lime sulfur mixture, 1% copper sulfate solution, or 70% thiophanate-methyl wettable powder 100 times solution, 40% asomate wettable powder 50 times solution, etc. This disease is inherently stubborn; some disease spots cannot be completely cured by scraping once and applying medicine several times, and sometimes re-scraping is needed, and severely diseased branches should be cut off when necessary. During the growing season, scraping of spots is generally not advisable; the above chemicals can first be applied to the spots to suppress the disease, and thorough scraping and treatment can be done in the dormant period. For old disease spots, scraping and treatment can generally be carried out after the beginning of winter.