Text/Fu Chunchang
Although the pear small heartworm is a major pest of pear trees, it is not small to apple trees, peach trees, cherry trees, plum trees, etc., especially for the growth of new shoots of peach trees, cherry trees, plum trees, etc. It is extremely harmful, which seriously affects the normal growth of young trees and the crown expansion of young trees.
In the early stage, it mainly harms the fruit of the hanging fruit tree, and when the early and middle ripe fruits are harvested, it is transferred to the new shoots to harm the new shoots.
It is widely distributed in China's region, in China's northeast, northwest, north China, South China and other regions have different degrees of occurrence, the late growth of plum trees, peach trees, cherry trees in the later stage of the new shoots is extremely harmful, especially the management of the extensive garden is particularly prominent, the larvae drill into the new shoots hazard, so that the young trees at the top of the new shoots dry death, after about ten days and then re-shoots, the offspring it produces overlap in turn, and the generations of several times increase, seriously affect the growth of new shoots, making it difficult for young trees to form as soon as possible, but also affecting the normal differentiation of flower buds, delaying fruit hanging, It has a great impact on the early yield and benefit of young trees. So it is a pest that cannot be ignored.
<h1 class="pgc-h-arrow-right" data-track="25" > the occurrence of small heartworms in pears</h1>
Pear small heartworm (also called Li Xiao heartworm in some places), it occurs 4∽5 generations a year, the fifth generation of mature larvae in the bark seams, soil shallow soil layer, grass root cracks, under the stone cocoon overwintering. Overwintering larvae begin pupating from early April to mid-April of the following year, overwintering adults begin to appear in late April, and feathering peaks from late April to early May.
Due to the vast territory of China, the temperature difference between the north and the south is large, and the adult sting may be about 10 days to half a month earlier due to the high temperature in the southern region, which requires technicians to use sweet and sour solution to induce adult insects to observe and grasp the sting time of adults (because adults have phototropism and chemotaxis).
1 to 2 days after the feathering of the sting adult worms began to mate and lay eggs, the eggs were scattered, the average egg laying was 32.5 grains, and the spawning time was mostly concentrated between 16:00 and 20:00 p.m., the eggs were laid on the fruit surface, leaf back and stalk depression, the egg stage was about a week, the larvae began to hatch, looking for suitable parts to enter the fruit or the new shoots, began to harm the young fruit and individual new shoots, at this time the young fruit core has not yet hardened, the larvae directly into the kernel of the harm, so that the affected fruit falls off as soon as possible, the larvae can be matured and defruited after about 10 days. It then dives into the cortex seam or ground, forms a cocoon at the grass roots, shallow soil layers or stones, and then pupates into pupae after 3 to 4 days, pupal for about a week.
Around the beginning of June, the first generation of adult insects appeared, mating and laying eggs in the fruit, at this time the core has basically hardened, and the second generation of larvae cannot enter the core, and only eat the pulp under the skin. It takes about 20 days from egg hatching to larvae ripening and fruiting, and after the old ripe insects are defruited, they look for a suitable place to cocoon and pupate, and the pupal stage is about a week. In early to mid-July, the second generation of adults appeared, the second generation of adults began to mate and lay eggs, so when the cherries have been harvested, most of the early and middle ripe peaches and plums have also been picked, at this time the adults will lay their eggs on the surface of the late ripening fruit or the stalk concave and the leaf back at the top of the new shoots, after about a week of incubation, the larvae begin to look for suitable parts to moth into the fruit or new shoots, and begin to harm the fruit and new shoots.
<h1 class="pgc-h-arrow-right" data-track="25" > prediction method</h1>
The fruit that began to be harmed had no obvious symptoms, but it changed color earlier than the general fruit and was easy to fall off; the new shoots that were endangered began to wilt, and the damaged parts began to dry up. After the mature larvae burrow out of the tree, they look for a suitable place to cocoon and pupate. In early to mid-August, the third generation of adults began to feather and lay eggs, and the adults continued to lay their eggs on the late ripening fruit or on the upper leaves of the new shoots, and after about a week of hatching, the larvae entered the fruit or the upper part of the new shoots and began to harm. After another 10 days or so, the larvae begin to age and descend the tree, looking for a suitable place to continue cocooning and pupating. Around mid-September, the fourth generation of feathered adults mated and laid eggs, continuing to hatch to harm late fruits and new shoots. Each generation of small heartworms varies from generation to generation. Due to climatic differences, 5 to 4 generations can occur in the south and 3 to 4 generations in the north.
If the pear small heartworm is not prevented on time, when the new branches are re-issued to about 15 centimeters, they are harmed by the next generation of pear small heartworm larvae, and the new shoots cannot continue to prolong normal growth. Therefore, we must not ignore this small pear heartworm, which has a great impact on the normal crown expansion of young trees of plum, peach and cherry, flower bud formation and early yield.
According to their own local region and climate, timely and accurate prediction of pear small insectivorous adult feathering and egg laying time, the general egg stage prevention and control for the best time, only in this best time time time medication prevention, in order to play the best effect, can reduce the harm of pear small heartworm to the minimum, so that young trees as soon as possible into the full fruit period, to achieve the purpose of increasing production and income.
<h1 class="pgc-h-arrow-right" data-track="25" > prevention and control method</h1>
1. Soil cultivation prevention and control
Before the emergence of overwintering adult feathers, that is, before the beginning of April, soil was cultivated under the tree tray for control. It is to cultivate about 10 cm of soil within a week from the trunk of the tree, so that the overwintering adults are starved of oxygen and suffocate, and after the feathering period is over, the soil layer under the tree is removed in combination with medium tillage.
2. Trap and kill adult insects
That is, the use of pear small heartworm phototropism and acidification, the use of fluorescent lamps or sweet and sour liquid (sugar: vinegar: water ratio is: 0.5: 1: 10 or rotten fruit fermentation liquid 4 times the liquid) to trap the adult insects.
3. Ground spray prevention and control
Before the overwintering adults are feathered or before the first generation of larvae are defruited, spray 25% parathion microcapsules under the canopy, use about 1 liter of the original solution per acre, add 60 to 80 liters (kg) of water to spray in the vertical projection of the canopy, and then use a rake to rake to evenly mix the medicine and soil. Or sprinkle octyl thion wettable powder under the tree, and then use the same method above to rake evenly, using medicinal soil poisoning.
4. Timely medication prevention and treatment
The medicine is given on time (once every 15 days) from the bell flowering period after the budding of the tree to the time before the leaves fall, combined with the control of other pests and diseases. Commonly used insecticides are: chlorpyrifos, perchloromethyl salt, cypermethrin, cypermethrin, urea 3, insect mite light and so on. As long as you follow the instructions of the medicine on time, you can play a good prevention and control effect.