What are the main pests of apple trees? A detailed guide to control methods
Apple is one of the fruits commonly eaten in daily life, with a great many varieties, and the varieties grown differ from region to region. During apple cultivation, it is very easily attacked by insect pests, so what are the several main pests of apple? What control methods are there?
1. What are the several main pests of apple?
1. Fruit-boring moths
Also known as fruit-boring pests, these are the most damaging group of pests on apple and occur commonly in every apple-producing region of our country. All fruit-boring moths damage the fruit by having their larvae bore inside to feed; the flesh is often eaten hollow or causes early fruit drop and rotten fruit, which not only directly reduces the yield and quality of the fruit but also deprives the damaged fruit of its proper commercial value, seriously affecting the grower's economic returns. Because these pests live concealed lives, with the larvae feeding inside the fruit, chemicals have difficulty reaching the insects, making control difficult.
The fruit-boring moths commonly found on apple trees mainly include the peach fruit moth (Carposina sasakii), the oriental fruit moth (Grapholita molesta), the apple fruit borer (Grapholita inopinata), the peach pyralid moth (Dichocrocis punctiferalis), the codling moth (Cydia pomonella) and the cotton bollworm (Helicoverpa armigera), among which the oriental fruit moth is widely distributed and commonly occurring, the peach fruit moth and the codling moth occur severely in localized areas, and the remaining species mostly occur only sporadically.
2. Red spider mites
In July, when more than 2 active red spider mites are observed per leaf in the orchard, immediately carry out chemical control, choosing 20% clofentezine suspension concentrate or 15% pyridaben emulsifiable concentrate at 1500-2000 times dilution for spraying, or alternatively 5% fenpyroximate suspension concentrate or 11% etoxazole suspension concentrate, which have good ovicidal effects, at 4000-5000 times dilution.
3. Spider mites
Spider mites are the most important group of pests on apple and occur over a relatively wide range. At present the most common is the hawthorn spider mite (Tetranychus viennensis); next is the apple spider mite (Panonychus ulmi, also called apple leaf mite or cotton red spider), which occurs mainly in northern fruit regions; and also the two-spotted spider mite (Tetranychus urticae), which is harmful throughout the country.
The apple spider mite damages on the underside of leaves, causing the leaves to lose their green color and drop early, seriously affecting the plant's nutrient synthesis and weakening the tree. Once the pest population density increases, white webs form on the underside of the leaves; the webbing forms very quickly and can cause serious damage within a short period, with the leaves scorching and dropping off.
2. What control methods are there for the several main pests of apple?
1. Agricultural control. In early spring, scrape off the loose bark on the trunk and around pruning and saw cuts to eliminate overwintering larvae. During the fruit tree's growing season, in combination with flower and fruit thinning and summer pruning, crush the larvae in rolled leaves by hand to reduce their damage.
2. Biological control. During the peak egg-laying period of the overwintering generation adults, release the pine caterpillar egg parasitoid wasp (Trichogramma dendrolimi) for control; the method is: based on the number of moths caught by sex pheromone traps for the apple leaf roller, start releasing wasps on the 3rd day after the adult emergence peak, then release wasps once every 5 days, for a total of 4 releases. The number released per tree each time is: 500 for the first release, 1000 for the second, and 500 each for the third and fourth. In addition, microbial pesticides such as Bacillus thuringiensis, Bacillus moritali and Beauveria bassiana can be sprayed to control the larvae. Other natural enemy insects include: Trichogramma confusum, the leaf roller braconid wasp Apanteles, the microgaster wasp Apanteles, and various predatory spiders.
3. Chemical control. In severely affected orchards, spray the whole orchard once at the early bud stage with 3-5 degrees Baumé lime sulfur mixture or 45% lime sulfur crystal at 60-80 times dilution to kill overwintering pests. Under conventional management, after petal fall is the key period for controlling the overwintering generation larvae, mid-June is the key period for controlling the first generation larvae, and August is the key period for controlling the second generation larvae. According to field observations, the period when overwintering larvae emerge from dormancy and the hatching period of each generation of larvae are the key periods for chemical control. On fruit-bearing trees, the control threshold is 2-3 insects per hundred leaf clusters, which can serve as a reference. Commonly used chemicals include: 35% chlorantraniliprole water-dispersible granules at 10000-12000 times dilution, 1% emamectin benzoate emulsifiable concentrate at 3000-4000 times dilution, 25% diflubenzuron suspension concentrate at 2000-3000 times dilution, 20% diflubenzuron suspension concentrate at 2000-3000 times dilution, 20% tebufenozide suspension concentrate at 1000-1500 times dilution, 24% methoxyfenozide suspension concentrate at 2000-3000 times dilution; in addition, chlorpyrifos, beta-cypermethrin, lambda-cyhalothrin and deltamethrin also have control effects on the pests.