Prevention and treatment of bacterial perforation in peach

Peach bacterial perforation is a disease with wide distribution and high incidence. Bacterial perforation occurs in peach producing areas all over the country, especially in coastal areas, lakeside areas, orchards with poor drainage and rainy years, which often occurs seriously. if it is not controlled in time, it is easy to cause a large number of fallen leaves and reduce the accumulation of nutrition. affect the formation of flower buds. It not only weakens the tree potential and reduces production in the same year, but also affects the results of the second year, resulting in a poor harvest. In addition to harming peach trees, the disease can also damage a variety of drupe fruit trees such as plums, apricots and cherries.

I. harmful symptoms

It mainly harms the leaves and can also damage the branches. At the beginning of the disease, the leaves are water-stained green dots, enlarged into round or irregular spots, purple-brown to black-brown, the sizes of the spots are generally about 2 to 3 mm, and there is a yellowish-green halo ring around the spot. After the spot has dried up, a circle of cracks are formed at the junction of the disease and healthy parts, and perforation is formed after falling off, or part of it is connected with the leaf.

After the branches are damaged, there are two different disease spots, one is called spring ulcer, the other is summer ulcer. Spring ulcers occurred on branches that grew in the summer of the previous year (the germs had invaded the previous year). When the first batch of new leaves appear in spring, dark brown herpes are formed on the branches, about 2 mm in diameter, and then expand as long as 1 to 10 cm, with a width of no more than half of the branch diameter, sometimes causing branch blight. At the end of spring (before and after flowering), the epidermis of the disease spot ruptured, the bacteria exudated and began to spread. Ulcers occurred more frequently in summer than at the end of summer, and lenticels were the center of the shoots in the same year, forming water-stained dark purple spots. After that, the lesion turned brown to dark brown, round or oval, slightly sunken, and the edge was waterlogged. The disease spot of summer ulcer is not easy to expand, and will soon dry up, so the spread effect is not big.

2. Infection cycle and disease conditions

The pathogen of the disease overwintered in the branch disease tissue, mainly in the spring canker spot. In the next spring, with the rise of temperature, the bacteria latent in the tissue began to move. Before and after flowering, the bacteria exudated from the diseased tissue, spread by wind, rain or insects, and invaded through the stomata of leaves and lenticels of branches. In the northern region, the disease occurred in May and was more serious in early June. The disease progressed slowly in summer drought and became serious in the rainy season. The incubation period of the pathogen varied with air temperature and tree strength. The incubation period was four or five days when the temperature was between 25 ℃ and 26 ℃, 9 days at 20 ℃ and 16 days at 19 ℃. When the tree was strong, the incubation period could be as long as 40 days. Warm, Rain Water frequent or foggy seasons were suitable for the disease, and the orchards with weak tree potential or poor drainage, poor ventilation and partial application of nitrogen fertilizer were more serious, and the disease degree was different with different varieties.

III. Prevention and control methods

To advocate the policy of "giving priority to prevention and comprehensive prevention", in accordance with the principle of "early treatment, small treatment, and cure", we must do the following:

1. Strengthen orchard management: in winter, combined with pruning to remove diseased branches, thoroughly clean withered branches, fallen leaves, fallen fruit and withered grass, and concentrate on burning to eliminate the source of overwintering disease. Pay attention to orchard drainage, reasonable pruning, so that orchard ventilation and light transmission is good, reduce orchard humidity. Increase the application of organic fertilizer, avoid partial application of nitrogen fertilizer, make the fruit trees grow healthily and improve the ability of disease resistance.

2. Chemical control: peach trees are sprayed with Baume 3 to 5 degrees stone sulfur mixture before germination. Spray 65% wettable Dyson zinc 300 to 500 times from the end of May to the end of June once or twice. Spraying zinc sulfate lime solution also has a good control effect, the formula is zinc sulfate 1 kg, lime 3 to 4 kg, water 150 to 200 kg.

3. Avoid mixed planting with stone fruit trees: in the construction of peach orchards, not only pure tree species and disease-resistant varieties should be selected, but also other stone fruit trees such as plums, apricots and cherries should not be planted nearby.