Key Technical Points for Early-Spring Pest and Disease Control in Peach Trees
As the early-spring weather gradually turns warm, various peach tree pests and diseases begin to revive, breed and multiply. Early-spring control of peach tree pests and diseases can effectively curb the occurrence and spread of many peach tree diseases and reduce the base population of insect pests. The occurrence, damage situation and early-spring control recommendations for the main peach tree pests and diseases are briefly introduced as follows:
1. Peach anthracnose
Occurrence and damage: This is the main fungal disease of peach trees in this region. The mycelium overwinters on diseased dead branches and diseased mummified fruit; in early spring of the following year it produces spores that infect fruiting branches, then successively spread to flowers and fruit, worsening the damage. In severe cases, a large number of fruiting branches die and large amounts of fruit rot. In the Shanghai area there are 3 disease processes in a year, found respectively on fruiting branches from mid-March to early April; on young fruit in early to mid-May; and on fruit during the ripening stage in June and July. The young fruit stage suffers the heaviest damage of the whole year.
Early-spring control methods: (1) Prune off dead branches, mummified fruit and stubby remnants on the tree, or the first diseased branches at the initial onset of disease around bud break to flowering, to eliminate the overwintering source of disease and prevent re-infection; (2) strengthen drainage, apply more phosphorus and potassium fertilizer, strengthen tree vigor, and avoid leaving branches too dense or too long; (3) at peach bud break, spray 1-2 times with 1:1:100 Bordeaux mixture (do not use after leaf expansion).
2. Peach bacterial shot hole
Occurrence and damage: This is a bacterial disease that overwinters on diseased shoots; in spring of the following year bacterial ooze exudes from the diseased parts and is spread by rain, wind and insects. It invades through stomata, lenticels and other openings. It generally appears after leaf expansion in mid-April; the plum rain season in May-June and the typhoon season in August-September are the peak periods of disease throughout the year. It mainly damages peach leaves and fruit, causing leaf shot hole and leaf drop and fruit cracking.
Early-spring control methods are the same as for peach anthracnose.
3. Peach crown gall
Occurrence and damage: This is a bacterial disease that mainly damages the roots and root crown, forming tumors, causing severely poor growth of the peach tree, stunted plants, few fruit of poor quality, and death of the whole plant in severe cases. The pathogenic bacteria survive in the tumor tissue or in the soil and can be spread by rainwater runoff or irrigation water, and by diseased nursery stock, invading through wounds.
Early-spring control methods: (1) Strengthen soil management, fertilize rationally, improve the soil, and strengthen tree vigor; (2) strengthen orchard inspection; for suspicious diseased plants, dig away the surface soil, and once disease is found, scrape it off with a knife or scrape it off thoroughly and drench the roots with KG84 for disinfection; for severely affected plants, dig them out and burn them.
4. Peach gummosis
Occurrence and damage: This is a physiological disorder of peach trees, occurring mainly on branches and trunks, though gumming can also occur on new shoots, leaves and fruit, causing the bark of affected branches and trunks to become rough, cracked and slow to heal. When gumming is severe, tree vigor declines, and the tree easily becomes an egg-laying site for the peach red-necked longhorn beetle, which accelerates the death of the peach tree. Gumming can occur throughout the entire growth period of the peach tree, but occurs most in rainy seasons such as the plum rain and typhoon periods, and is more severe in old and weak trees.
Early-spring control methods: Strengthen integrated management, promote normal growth and development of the tree, and enhance tree vigor.
5. Mulberry white scale
Occurrence and damage: Also known as the mulberry shield scale and peach white scale, it is an important pest of peach trees. Mated adult females overwinter on branches and trunks; in the Shanghai area there are three generations a year. Overwintering females begin laying eggs in mid-April; the occurrence periods of the three generations of nymphs are respectively early to mid-May, early to mid-July and early to mid-September each year. Female adults and nymphs damage peach new shoots, branches and trunks and fruit, causing severe decline in tree vigor and a sharp reduction in fruit yield and quality, and even death of the whole tree.
Early-spring control methods: Before bud break, spray 1-2 times with 5 degrees Baume lime sulfur mixture, or 100 times machine oil emulsion, to kill the overwintering adult females. When the insects are densely massed in patches, before spraying they can be brushed off with a stiff-bristled brush and then sprayed, to facilitate penetration of the spray liquid.
6. Peach red-necked longhorn beetle
Occurrence and damage: Commonly known as the tree-sawing fellow, it is an important pest of peach trees. Larvae overwinter in the damaged parts of branches and trunks, and generally complete one generation in 3 years. Mature larvae pupate in May; adults appear in mid-to-late June; eggs are laid from late June to early July; larvae begin overwintering in late October. The larvae bore into and feed on the cortex and xylem of peach branches and trunks, weakening tree vigor and shortening lifespan. In severe cases, peach trees die in patches.
Early-spring control methods: After locating the damaged parts based on boring dust and insect frass on the branches and on the ground, pierce the larvae to death with a wire.