A Complete Guide to Identifying and Treating Common Pests and Diseases of Peach Trees

Peaches, due to their broad market sales, good economic returns, and ease of cultivation and management, are favored by many farmer friends and are grown very widely in China. Taking this group member's question as an opportunity, today I will give everyone a popular overview of common peach tree diseases and their treatment methods.

Common diseases

Peach gummosis, peach bacterial shot hole, peach scab, peach anthracnose, bacterial crown gall, etc.

① Peach gummosis

It is an important disease of branches and trunks, causing tree decline, reduced yield or tree death, and has two types: non-infectious and fungal-infectious. In spring and summer, on the current year's new shoots, with lenticels as the center, variously sized protruding lesions appear, after which colorless translucent soft gum flows out

At wounds on other branches and trunks or near the bud scars of 1-2 year old wood, translucent gum also flows out, after which the gum turns into tea-brown crystals; after absorbing water it swells, becoming a jelly-like colloid. In severe cases the bark cracks, branches and trunks die, and the tree declines.

Treatment method:

First remove the gum, dilute Kuifujing 50-100 times, and use a brush to evenly apply it to the diseased area; after 1-2 applications it can be prevented and eliminated. For newly occurring large-area gummosis, dilute Kuifujing 100-200 times and spray evenly directly on the diseased parts.

② Peach bacterial shot hole

This disease is caused by bacteria and mainly harms leaves, fruit and new shoots. When leaves first become diseased, water-soaked yellowish-white to white small spots appear, later forming round, polygonal or irregular purplish-brown to dark brown lesions about 2-4 mm in diameter, surrounded by a yellow-green water-soaked halo, after which the lesions dry up and fall off to form shot holes. When fruit becomes diseased, dark purple round lesions with depressed centers appear on the fruit surface with lenticels as the center, the edges are water-soaked, and in the later stage the epidermis in the center of the lesion cracks. The pathogenic bacteria overwinter in the tissues of the branches; the following year, as temperatures rise, the latent bacteria begin to activity and form lesions. Before and after peach trees bloom, the pathogen oozes from the diseased tissues and spreads via wind and rain or insects

Leaves generally become diseased in May; high temperature and humidity favor infection by the pathogen, and the disease worsens. Orchards with weak tree vigor, poor drainage or excessive nitrogen fertilizer have more severe disease, and differences in disease resistance among varieties are closely related to the severity of the disease

Treatment method:

Spray Yebingling at 1000-1500 times dilution to quickly kill the pathogen and block the spread of the disease; when the disease is severe it can be increased to 800-1000 times dilution. It is recommended to apply once every 7-10 days, and 2-3 consecutive applications are sufficient.

③ Peach scab

Also called black spot, it mainly harms fruit and also attacks new shoots and leaves. Fruit is mostly affected at the shoulders. The lesions on the fruit are initially green and water-soaked, and after expanding become black-green and nearly round. When the fruit ripens, the lesions turn purple or dark brown; the lesions are limited to the fruit skin and do not penetrate into the flesh; in the later stage the lesions become suberized and crack.

The time when the pathogen invades the fruit is 6 weeks after petal fall, about from mid-to-late May to one month before ripening. After shoots are damaged, the lesions are oblong and light brown, later turning grayish-brown to brown, with dark brown to purplish-brown surroundings, raised, and gummosis often occurs.

Treatment method:

Bacterial shot hole, scab and anthracnose are treated the same way

④ Peach anthracnose

When young fruit become diseased before pit hardening, brown-green water-soaked lesions appear on the fruit surface, after which the lesions expand and become depressed and produce pink sticky spore masses. The lesions on the young fruit enlarge along the fruit surface and reach the fruit stalk, then penetrate deep into the fruit branch, causing the leaves on the new shoots to curl upward longitudinally, which is one of the characteristics of this disease.

Most affected fruit drop in May. When the disease occurs near fruit ripening, the symptoms on the fruit surface are the same as before, and there is also obvious concentric ring-shaped shrinkage, and finally the fruit soft-rots and drops. In early spring, when peach trees bloom and during the young fruit stage, low temperature and abundant rain favor the disease; during fruit ripening, warm, cloudy and foggy, high-humidity environments lead to severe disease.

Treatment method:

Bacterial shot hole, scab and anthracnose are treated the same way

⑤ Crown gall

It occurs on peach roots, the root crown and stems. The affected parts first form gray-white tumor-like growths, tender in texture; the tumors continuously grow larger, turn brown, become lignified, dry and hard in texture, with an irregular surface, rough and cracked.

Treatment method: dig out the root system near the main trunk, scrape off the root tumors and disinfect with Genfusuxiao at 600 times dilution, apply wound healing agent to the wounds for protection, replace the surrounding soil, apply more organic fertilizer, and irrigate with rooting powder to promote root sprouting and enhance tree vigor.

Common pests

Green peach aphid, peach fruit borer, peach leafminer, small green leafhopper, hawthorn spider mite, white peach scale, peach globular scale, brown marmorated stink bug, red-necked longhorn beetle, etc.

① Green peach aphid

Adults and nymphs cluster on the underside of leaves; damaged leaves curl longitudinally from the leaf margin toward the underside, tissues become thickened and chlorotic, and the aphids excrete sticky honeydew that contaminates branches and leaves, inhibiting new shoot growth and causing leaf drop.

Generally more than 20 generations occur per year; they overwinter as eggs on peach trees, and wingless viviparous females can also overwinter on spinach in windbreaks or, with cruciferous vegetables, in vegetable cellars. For those overwintering as eggs on peach trees, the following year from peach bud break to the flowering stage the eggs begin to hatch and cluster on tender buds to suck sap. From late March to April, they reproduce and cause damage by parthenogenesis.

② Hawthorn spider mite

It occurs 5-9 generations per year, overwintering as female adults in cracks in the rough bark of trees and in the soil near the trunk, in dead leaves and weeds. In early April, at the end of peach blooming, they emerge from dormancy and harm newly grown tender tissues. They lay eggs after the full bloom stage, and the eggs finish hatching after petal fall.

One month after petal fall is the peak hatching period for the second generation of eggs. After June, with high temperatures, reproduction is fast, generations overlap, damage is severe, and it often causes large amounts of leaf drop. Overwintering females continue to appear successively until September and lie dormant to overwinter.

③ Brown marmorated stink bug

Adults and nymphs suck the sap of tender fruit, tender leaves and tender shoots. After fruit is damaged, it becomes uneven and deformed, and the flesh at the damaged site becomes hollow and suberized. After peach fruit is damaged, gum flows from the puncture site, the flesh sinks, forming hard dead spots, and young fruit often drop when damaged, greatly affecting yield and quality.

Adults overwinter under eaves of village houses and in cracks in walls and stone crevices; the following year they begin to emerge and become active in late April and fly to peach orchards to cause damage. In June they lay eggs on the underside of leaves; the egg stage is about 10 days; hatching begins in late July, and they cluster near the egg masses to cause damage, then gradually disperse. In July and August adults begin to emerge, causing damage until September, when they seek suitable places to overwinter.

④ Scale insects

Scale insects attach themselves and suck the host's sap with nymphs and adults. Their numbers are especially large; some completely cover the bark, overlapping in layers, forming an uneven gray-white waxy substance and excreting sticky liquid that contaminates the tree, making it look oily. Damaged branches develop poorly, and in severe cases the entire branch or whole tree dies. Branches 2-3 years old are damaged most severely.

The following year, egg laying begins in late April, with eggs laid under the scale; after laying, the female shrivels and dies. Nymphs begin hatching in early May; after crawling out from under the mother's scale, they crawl everywhere on the branches and trunks. After a few days they become immobile and begin to secrete waxy filaments; after molting they form a scale and insert their mouthparts under the bark to suck sap. After the second molt, females become adults and remain immobile under the scale feeding; after the second molt, males become pupae, densely packed in patches on the branches and trunks. In mid-June the first generation of adults begins to emerge. In late June egg laying begins.

⑤ Red-necked longhorn beetle

It overwinters as larvae in tunnels in the trunk; the following year from March to April it resumes activity, boring irregular tunnels under the cortex and in the xylem, and expelling large amounts of reddish-brown frass fragments outside the bore holes, piling up outside the holes and on the ground at the base of the trunk. Damage is most severe in May and June; in severe cases the trunk is completely hollowed out and the tree dies. After the larvae mature, they open a frass-expelling hole to the outside, use secretions to bind frass and wood chips, and make a cocoon in the tunnel to pupate. In June and July, adults emerge, bite their way out, mate and lay eggs in the rough bark crevices at the base of the tree and at the branch forks of main branches. After hatching, the larvae first bore and feed under the bark, then go through diapause to overwinter. The following spring they continue to bore and feed on the cortex, and from July to August they bore upward into the xylem to form winding tunnels; after another winter, in May and June of the third year they mature and pupate, emerging as adults.

Treatment methods for various pests:

Before peach trees bud, evenly broadcast the medicinal fertilizer “Sachong'an” at the roots, then water thoroughly. This effectively controls many pests such as green peach aphid, hawthorn spider mite, brown marmorated stink bug, scale insects and red-necked longhorn beetle. One application provides highly effective control of all kinds of pests occurring on peach trees for more than half a year, with no need for multiple agents and no need for frequent spraying, truly achieving highly efficient pest control, saving labor, time and effort, and being safe for the fruit.

When pests occur, irrigate the roots with the medicinal fertilizer “Sachong'an”; 5 days after application, the agent reaches all parts of the tree to carry out insecticidal work and durably controls the pests so they no longer occur.