What types of aphids attack peach trees in early spring? How can they be controlled?
In March, the leaf buds of peach trees begin to swell; after late March, most varieties enter the flowering stage, and root growth accelerates. At this time, peach tree aphids easily appear, and if not actively treated, they will directly affect yield. So what types of aphids attack peach trees in early spring? How can they be controlled?
I. What types of aphids attack peach trees?
1. Green peach aphid
It produces 10-30 generations per year, overwintering as eggs in the shoot tips, bud axils, small branch crotches and bark crevices of peach trees. The following year, from the peach tree's bud break to the flowering stage, the eggs begin to hatch, cluster on the tender buds and suck the sap. From late March, they begin to reproduce and cluster on the undersides of leaves to cause damage. In May, their numbers increase sharply and the damage is most severe, and they begin to produce winged aphids that fly to vegetables to continue reproducing and causing damage.
2. Mealy plum aphid
It produces more than 20 generations per year, overwintering as eggs in the branches and bud crevices of peach trees, and begins to hatch and cause damage from March to April of the following year. From May to June, it reproduces fastest and the damage is most severe.
3. Peach leaf-curling aphid
It produces more than 10 generations per year, overwintering as eggs on peach trees. The following year, after the peach trees sprout in mid-to-late March, it begins to hatch and cause damage, with the most severe damage in May and June.
II. How can aphids on peach trees be controlled in early spring?
1. Strengthen orchard management
Together with spring pruning, cut off the damaged shoots and burn them in a centralised way.
2. Reasonable companion cultivation
Tobacco, Chinese cabbage and other crops should not be planted between the rows of the peach orchard or nearby, so as to reduce summer breeding sites for aphids.
3. Medicinal smearing
Use a bristle brush to apply a 6 cm wide ring of insecticide around the trunk, then wrap it well with paper or plastic sheeting; the effective period is about 15 days.
4. Protect natural enemies
Ladybirds, hoverflies, green lacewings and parasitic wasps are the natural enemies of aphids; broad-spectrum pesticides should be sprayed as little as possible, and spraying should be avoided when natural enemies are abundant.
5. Yellow trapping and killing
The green peach aphid is attracted to yellow, so yellow boards can be hung or the branches and trunk coated with yellow grease or machine oil to attract and trap them.
6. Spraying pesticides
In spring, after the eggs hatch, when the peach tree shows red and after the flowers fall, spray beta-cypermethrin, imidacloprid, acetamiprid or spirotetramat alone or in combination, alternating between them. For the mealy plum aphid, washing powder solution can be added to the spray liquid to increase adhesion and remove the waxy powder from the insect bodies.
III. How can peach weevils be prevented?
1. Capture adults
Taking advantage of the adults' feigning death, in the early morning before the dew has dried, spread a cloth sheet under the tree and shake the branches; the adults fall down when startled, and are then gathered and dealt with. The effect is best after rain, when the most adults appear.
2. Spraying for control
During the peak emergence period of adults in April, spraying 90% trichlorfon at 1000 times dilution is effective, or 40% dimethoate emulsion at 1000 times dilution, or 80% dichlorvos at 1000 times dilution.
3. Remove infested fruit
Frequently pick up fallen fruit and remove bored fruit from the trees, then compost them or soak them in water, which can kill larvae that have not yet left the fruit.
4. Spread pesticide on the ground
In spring, before the adults emerge from the soil, spread 50% carbaryl powder under the trees in the orchard, or during the peak emergence period of adults, spray 25% phoxim capsule formulation at 100 times dilution on the ground beneath the tree canopy.