Soon after the new shoots of the pear orchard are pumped in the spring, the phenomenon of young shoots being bitten off the tip is more common, and some farmers come to consult what is the pest hazard and how to prevent it? In general, the young shoots of pear trees are truncated, and it can be basically judged that it is caused by the pest of pear stems and bees. Pear stem bees in Jiangxi pear tree cultivation area common occurrence, is the main pest of pear tree new shoots, some parks have been affected year after year, the occurrence of serious new shoots damage rate of up to 80%, full of broken shoots, affecting the formation of young tree crowns, adult number of fruit branches can not be formed, the tree potential and yield has a great impact. The following author will talk to you about the harmful symptoms, occurrence rules and prevention methods of pear stem bees for reference.
<h1>1. What are the symptoms of pear stem bees harming pear trees? </h1>
Pear stem bees, also known as folded beetles and pruners, belong to the order Hymenoptera and the stem bees. The pear stem bee uses a saw-shaped egg laying device to cut off the young shoots of the pear tree with adult insects, and the newly broken shoots die, and there are 2-3 cm short piles in the lower part of the young shoots, which is convenient for the pear stem bees to spawn and reproduce.
Gently tear open the stem, you will find 1 egg in the shape of a rice grain Photo: Zheng Xiaoliang
The pear stem bee will only lay 1 egg for each new shoot sawn off, and 1 female adult can harm 20-30 new shoots, and after the eggs hatch, the larvae moth in the marrow of the short pile of new shoots, causing the victim to die, seriously affecting the normal growth of the tree.
Pear stem bee larvae feed
After eating, the moth will moth into the marrow of the upper annual branch, twist the worm body 1 cm from the fork, and form a cocoon with its head facing upwards, entering a state of summer into winter.
Linger bee old ripe larva dormant
<h1>Second, the occurrence of pear stem bees</h1>
Pear stem bees occur annually in the south, overwintering in the infested branches as larvae or pupae, pupating in mid-to-late February of the following year, and adults feathering during the flowering period of pear trees in late March. After 3-5 days after feathering, adults fly out of the infested branches, then mate and lay eggs, the eggs hatch after 7-10 days to moth young shoots, and in June-July, the larvae mature and overwinter in cocoons in the infested branches.
It has been observed that the adult stem bee branching time lasts for 6-8 days, and the same day after the emergence of the stem can cause harm to the pear shoots; with the increase of the number of adult branches, the degree of harm is aggravated.
Pear stem bees
The emergence stage of adult pear stem bees is closely related to the early spring climate and the length of pear tree shoots. From the end of March to the beginning of mid-April, if the weather is clear and the maximum temperature of the day rises sharply above 20 °C, the adult insects will emerge in large numbers and harm new shoots. When the pear tree is 5 cm long, the adults begin to lay eggs; as the new shoots grow, the harm increases; when the new shoots grow to 8-12 cm, the harm peaks; when the shoots exceed 15 cm, the harm decreases sharply.
<h1>3. What are the methods for controlling pear stem bees? </h1>
Because the larvae of the pear stem bee are hidden in the pear branches, and the new leaves are tender and weak, the pear is in the flowering stage, and it is easy to produce drug damage with medication, which brings great difficulties to the prevention and control. The following measures are often used in the production of pear trees:
Pear trees are infested with pear stem bees during the flowering period
1. Pharmaceutical prevention and control
Grasp the pear stem bee branching stage, immediately administer the drug after feathering and before spawning, and the control agent can choose permethrin (high-efficiency cypermethrin, cypermethrin), avermectin, etc.; when the new shoots grow to 8-12 cm, special attention should be paid to prevention and control. When spraying, pay attention to evenly spraying the inside and outside of the canopy, the front and back of the leaves. Spray as much as possible to avoid the peak of flowering, generally earlier than before flowering or extended to fall flowers.
2. Kill adult insects
In the spring of the pear tree, taking advantage of the habit of adult insects to stop the leaf back, the branches are shaken in the morning and evening and on cloudy days, and the adults are shaken to shake the adults and artificially catch the adults.
Yellow plate sticky kill
3. Hang the armyworm board
In the initial flowering stage of pear trees, 12 yellow double-sided sticky insect plates of 20 cm * 30 cm per acre are suspended, and the hanging height is 1.5-2 meters from the ground. The effect of the armyworm is good, each sticky worm board can stick to kill 1000 adult insects, if due to the high density of pear stem bees, the armyworm board should be replaced in time after the sticky board is full.
4, cut the worms for many years
In winter, the dead branches formed by the hazards of the year are pruned, and the new shoots that are killed are pruned in the spring and summer, and destroyed to reduce the source base of the second year.
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