What to Do When Grapes Get Pests? A Detailed Guide to Practical Control Methods
Grapes are a common fruit in daily life, and they hit the market in large quantities every summer, making them very popular. So what should you do when grapes get pests?
1. Grape phylloxera
Grape phylloxera is a destructive pest and also an important quarantine target. Grape phylloxera overwinters as nymphs on the main roots and lateral roots of grapes; it becomes active in spring the following year, and after feeding it reproduces by parthenogenesis, meaning it lays eggs without mating, producing 5-6 generations. After the grape root system is damaged, tumor-like growths appear, initially bright yellow, later turning brown and rotting.
Control methods:
(1) Strengthen quarantine of nursery stock and prohibit the purchase of nursery stock from epidemic areas.
(2) Disinfect nursery stock and soil. First soak the nursery stock or cuttings in 30-40°C water for 5-7 minutes, then soak them in 50-52°C hot water for 7 minutes, which can kill most pests. Injecting 36-72 grams of carbon disulfide per square meter of soil can kill most phylloxera.
(3) Chemical root drenching. In affected areas, pyrethroid-type pesticides such as 2000-3000 times diluted fenvalerate, cypermethrin, and deltamethrin can be used for root drenching in spring and autumn.
2. Grape tiger longhorn beetle
The grape tiger longhorn beetle mainly damages one-year-old fruiting canes as larvae, and perennial branches are sometimes also damaged. In August, adults lay eggs on the branches and vines, and the larvae bore into and feed on new shoots. Sometimes a single fruiting cane contains several larvae, which tunnel and feed in sections. The areas near the nodes of damaged canes turn black, break easily, and may even die.
Control methods:
(1) During winter pruning, remove damaged canes and burn them in a centralized manner.
(2) In August, during the adult egg-laying period, continuously spray 80% dichlorvos emulsifiable concentrate at 1000 times dilution 2-3 times, ovicide-insecticide quick-kill at 1500 times dilution, or insecticide star at 1000-1500 times dilution, which can kill some adults and reduce egg production.
3. Grape brevipalpus mite
The red spider mite occurring on grapes is mainly the brevipalpus mite, which damages grape leaves, fruit stalks, and fruit clusters. When leaves are damaged, many dark brown spots appear, and in severe cases they scorch and fall off. When fruit clusters are damaged, the fruit stalks and rachis turn black, the tissue becomes brittle, and they break very easily. When berries are damaged, the surface takes on a rust color, the skin becomes rough, and sometimes cracks. The grape brevipalpus mite has 6-7 generations per year, overwintering as female adults in cracks of old bark, leaf axils, and loose bud scale hairs, and begins to emerge and cause damage in mid-to-late April the following year.
Control methods:
(1) After grapes are taken out of the soil and placed on the trellis and before bud break, spray 3°Be (Baume degree) lime sulfur mixture plus 0.3% laundry detergent for control.
(2) During the growing season, spray several times continuously according to the occurrence and damage situation. You can use white mite kill net at 2000 times dilution, red-white total kill at 2000 times dilution, or saomiejing at 2000 times dilution. Various pesticides should be used alternately to delay resistance.
4. Grape two-spotted leafhopper
The two-spotted leafhopper, also called the two-dot leafhopper or small fierce insect, mainly damages leaves, and in severe cases causes early defoliation of grapes, resulting in reduced yield. Adults are pale yellow overall, have 2 generations per year, and overwinter as adults in stone crevices and weeds near the vineyard. In May of the following year, as grape leaves unfold, they lay eggs on the plants and cause damage.
Control methods:
(1) In autumn, thoroughly clear fallen leaves and weeds in the vineyard to reduce the overwintering insect population base.
(2) During the growing season, timely tip pruning, tying vines, and handling secondary shoots can improve ventilation and light conditions on the trellis surface and reduce damage. During the adult egg-laying period and the concentrated nymph damage period, spray 40% dimethoate emulsifier at 2000 times dilution, or 75% phoxim emulsifier at 1500 times dilution, imidacloprid at 3000-4000 times dilution, or 4.5% beta-cypermethrin at 1500-2000 times dilution.
5. Grape clearwing moth
The grape clearwing moth has 1 generation per year. Larvae overwinter inside grape vines, and after hatching the larvae bore into the tender stems from the base of the leaf stalk of new shoots to cause damage. A large amount of frass often accumulates near the boring hole, and the damaged part often swells like a tumor, causing leaves to turn yellow and fruit to drop. Larvae begin damaging in July and overwinter in thick vines by October.
Control methods
(1) During winter pruning, damaged swollen branches should be cut off and burned.
(2) In June and July during the emergence period, frequently inspect tender branches. If wilting, boring holes, or frass are found, inject 50% phoxim emulsifier at 1000 times dilution through the hole, then seal the insect hole with clay. You can also spray yishaniao at 2000 times dilution or chlorpyrifos at 1000-1500 times dilution.