How to prevent and control ornamental peach rot disease in winter and spring?

Peach trees have important value and significance both in agricultural production and in garden ornamental use. The flowers are gorgeous, and every time the peach blossoms open in the third month of spring, they always attract a large number of people to come and admire them. So what are the winter and spring control measures for ornamental peach rot disease?

1. Symptoms and patterns of ornamental peach rot disease

Peach tree rot disease, also called dieback disease, mainly harms the main trunk and main branches, causing bark rot, branch death and tree death.

When the lesion first appears, the bark is slightly raised and feels soft when pressed with a finger. As it continues to develop, the diseased part becomes slightly sunken, the bark exudes gum, and gum spots the size of rice grains can be seen on the surface, initially yellowish-white, gradually turning brown, then brown to black. The diseased bark tissue under the gum spots rots, is slightly swollen and moist, yellowish-brown, and has an alcoholic smell. The lesion expands longitudinally and soon can reach the xylem. In the later stage, the diseased part shrinks and sinks, with densely packed small black dots, and when the air is humid, yellowish-brown thread-like spore tendrils ooze out from them.

Peach tree rot disease mainly invades through wounds and lenticels, and cracks formed by frost injury are an important route for pathogen invasion. Orchards with poor soil, low-lying terrain, poor drainage, and poor management have severe disease; autumn with excessive rain, excessive nitrogen fertilizer causing excessive vegetative growth, and poor cold resistance lead to severe disease.

2. Control measures for ornamental peach rot disease

1. Strengthen the tree to prevent disease

(1) Reasonable load: thin flowers and set fruit according to the tree's growth condition and fertilization level.

(2) Increase fertilizer and water: apply more organic fertilizer, increase phosphate fertilizer, potassium fertilizer and trace element fertilizers, and do not apply too much nitrogen fertilizer.

(3) Protect leaves and promote roots: promptly control diseases and insect pests that cause early defoliation of peach trees.

2. Pay attention to protecting the tree body

(1) Avoid frost injury and sunscald: one effective measure to prevent frost injury to peach branches and trunks is whitewashing the trunk to reduce the temperature difference between day and night; the second is tying straw around the trunk to prevent freezing.

(2) Protect wounds: larger saw cuts should be smoothed flat, then coated with varnish or thiophanate ointment, S-921 antibacterial agent, etc. for protection. After larger lesions are cured, bridge grafting should be carried out promptly and protected.

3. Treat lesions promptly

(1) Scrape the bark: peach tree rot disease generally damages the shallow layer of the bark, so scrape off the lesions before the peach tree buds. After scraping away the diseased tissue, mix 70% thiophanate-methyl wettable powder and vegetable oil at a ratio of 1:2.5, and apply it to the diseased part; this has a good effect on curing lesions. You can also apply 843 rehabilitation agent stock solution, etc., to prevent recurrence of the disease scars.

(2) Mud dressing control: take fresh soil and mix it evenly with clean water; the moisture level should be such that a mud ball squeezed by hand can stick to the bark. Then apply it to the diseased scars of the fruit tree, with a thickness of 3-5 cm, extending 5 cm beyond the diseased scar around it, then wrap it tightly with plastic film and tie it firmly to prevent water evaporation and mud falling off. After 1 year, remove the plastic film and mud. The cure rate of this method is above 85%.

3. Pay attention to distinguishing peach tree gummosis

Peach tree gummosis mostly occurs on the main trunk and main branches of older peach trees. In the early stage of the disease, the lesion bulges centered on the stomata, is dark brown, and the surface is moist. Under the cortex of the lesion there is yellow viscous gum liquid.

The lesions are elongated or irregular, generally confined to the cortex, but on aging trees they can extend deep into the xylem. Later, the diseased parts gradually dry out and sink, become dark brown, and larger cracks appear.

In the late stage of the disease, a large number of small black dots (stromata) that are spindle-shaped or nearly round grow on the surface of the lesions. Sometimes several small black dots are densely clustered together and exposed from cracks in the bark, generally 1 to 8 mm in size. Old trees affected for many years become extremely weak, and in severe cases the entire lateral branch or the whole tree dies.