What are the control methods for insects on grape leaves?
Grape is one of the oldest fruit tree species in the world. Grape fossils have been found in strata from the Tertiary period, which shows that grapes were already widely distributed in Europe, Asia, Greenland and other regions at that time. Grapes taste very delicious, and under modern artificial cultivation, grapes can be bought in all four seasons. Although grapes are delicious to eat, growing grapes is not an easy task, so what should be done when insects appear on grape leaves?
I. Control of insects on grape leaves
At every stage of grape growth and development, the plants can suffer damage from many kinds of pests, causing a decline in quality and yield. There are more than 300 kinds of pests that harm grapes, and generally more than 10 kinds occur commonly and severely. The piercing-sucking pests that damage buds and leaves mainly include the grape leafhopper, green plant bug, and onion thrips, among others. Among chewing mouthpart leaf-eating pests, the most common include the grape hornworm and scarab beetles, all of which cause grape tender shoots to wilt and leaves to scorch and fall early. When insects appear on grape leaves, the pest species should be identified as early as possible and the right treatment should be applied.
The grape leafhopper generally uses nymphs and adults to pierce and suck the sap of new shoots and tender leaves. When the insect population density is high, small white spots on the leaf surface often join together, causing leaves to wither and fall early, which greatly affects both appearance and fruit production. The main control methods are clearing weeds and fallen leaves in winter and turning the soil to eliminate overwintering insects. In summer, strengthen cultivation management by timely pinching, pruning, intertillage, hoeing weeds, and managing secondary shoots well to maintain good light and ventilation conditions. Commonly used pesticides include 80% dichlorvos emulsifiable concentrate, 50% phoxim emulsifiable concentrate, 50% malathion emulsifiable concentrate, and 50% fenitrothion emulsifiable concentrate, sprayed at 2000-fold dilution.
The adults and nymphs of the green plant bug damage the terminal buds, side growing points, and tender leaves of the plant, affecting normal growth and causing leaves to become tattered. The control method is to clear mugwort-type weeds and miscanthus and other miscellaneous trees around the vineyard. In the vineyard, avoid intercropping with leafy vegetables, taproot vegetables, and similar crops. In rainy seasons, pay attention to ditching and drainage, intertillage and weed control, and reducing humidity in the vineyard. Commonly used pesticides include 35% saidan emulsifiable concentrate, 10% imidacloprid wettable powder, 10% chlorfenapyr emulsifiable concentrate, and 20% methomyl emulsifiable concentrate at 2000-fold dilution, among others.
Adult onion thrips mostly move, feed, and lay eggs on the underside of tender upper leaves of the host. Nymphs mostly feed on both sides of the leaf veins, causing silver-gray markings. The main control methods are clearing weeds and dead tree leaves in the orchard in winter and spring, and concentrating efforts in September to October and early spring to eliminate thrips damaging the plants, so as to reduce the insect source. For chemical control, in early spring at the initial stage of damage, promptly spray 10% imidacloprid wettable powder at 2000-fold dilution, or 1.8% abamectin emulsifiable concentrate at 3000-fold dilution, or 0.12% Tianli II (miechongding) wettable powder at 1500-fold dilution, among others.
After hatching, the grape hornworm does not eat the eggshell, and mostly rests on the main vein on the underside of leaves or on leaf stalks. When the damage is relatively severe, it often eats the leaves bare. The control method is to dig out overwintering pupae in combination with winter soil mounding and spring soil removal in the vineyard. In combination with summer pruning and other management work, look for damage symptoms and ground frass to catch larvae. For chemical control, mix and spray trichlorfon, dichlorvos, parathion, and other pesticides, using the usual concentration.
Scarab beetles mainly damage the plant's tender buds, young leaves, and flower buds. The damaged areas appear notched or incomplete, and in severe cases they can be eaten bare. The control method is to investigate and grasp the peak occurrence period of adults, take measures, and control them in time. Generally, use 50% phoxim emulsifiable concentrate at 200-250 grams per mu, add water at 10 times and spray it onto 25-30 kg of fine soil, mix well to make poisoned soil, or use 50% phoxim, 50% parathion, or 20% isofenphos-methyl pesticide with water and seeds at a ratio of 1:30:400-500 for seed dressing. For chemical control, use 3.5% fluoroacetonitrile · bromine emulsifiable concentrate at 90-120 ml/mu, 40% chlorine · phoxim emulsifiable concentrate at 250 ml/mu, and other agents for root irrigation, pouring 150-250 ml per plant.
The above are the main pests that harm grape leaves and their control methods. When carrying out control, prevention must be the priority and timely treatment must be carried out.