Why bagged pears are harmful to yellow flies

With the promotion of fruit bagging technology, pear bagging has increased year by year. All those who operated according to the bagging procedures received the effect of reducing pests and diseases, enhancing fruit coloring, and improving the smoothness and appearance quality of fruit peels. At the same time, it was found that bagged pears were more severe than those that were not bagged, especially if they were not bagged. Pay attention to the prevention and treatment of pear orchards, resulting in the most infestation and the greatest loss.
The reason why bagged pears are prone to yellowflies is that the yellowflies tend to hide in a dark and sheltered environment and have a mild and dry climate. Pear fruit bagging, just in the bag to create a shade to protect the light from the environment, so there will be more; and the temperature inside the bag is higher than the outside of the bag, it will spread out to inhabit and feed, so many harmed , rotten fruit, heavy losses.
It has been observed that in early spring drought, the temperature rises quickly and stably, winter eggs hatch early, there is little rain, and the population density increases rapidly; otherwise, it delays and increases slowly. Temperature 17.5 °C ~ 24.7 °C, relative humidity in 50% ~ 71%, the population increased sharply, the temperature dropped to 13 °C ~ 16 °C, relative humidity of 78% ~ 82%, the amount of insects dropped. Yunnan has a long period of drought in the late spring and early summer this year. The weather is sunny, the air is dry, the temperature is high, and the humidity is low. It is the most suitable climate for the occurrence of the yellowfly, so we must pay attention to prevention and control.
First, the distribution and harm Pyralidae, alias Tenebrio, Homoptera insects. Located in the pear-producing areas of Liao, Yi, Hui, Su, Yu, Shan and Chuan provinces, Yunnan has also occurred in the past more than a decade. Single food, only harm pears. The piercing and sucking mouthparts of nymphs and adults are used to pierce the branch tender skin and pulp to suck the sap. They are often clustered around the pods of the fruit and harmed. The victim is turned into a brown or black plaque, commonly known as the “top plaster” and “black plaster”. "" Black Ditch." The heavy fruit of the victim, the pulp tissue gradually decayed and fell off; the lighter damage to the quality and the value of the commodity was one of the pests that caused a large economic loss to the plow.
Second, the morphological characteristics of the whitefly have dry mother, sex mother, common type and sexual type four, the first three are female, is parthenogenetic. The morphology of the adults was similar. The body was slightly ovoid, with a thin layer of wax powder, 0.8 mm long, bright yellow, shiny, abdomen without abdomen, no wings, no tail pieces, and well-developed. Sexual type, oval body length, smaller than the first three, female adults 0.47 mm long, male adult 0.35 mm, body color is bright yellow, mouthparts degradation. Overwintering eggs and nymphs are light yellow, and the nymphs resemble adults. They are only slightly smaller.
Third, the occurrence of law occurred in 6 to 10 generations a year, nymphs 4 instar, the eggs in the fruit within the Taiwan marks and branch skin overwintering. The wintering eggs begin to hatch in mid-March. The sap is sucked on the tender skin under the fruit pedicles and the branches of the branches. After a suitable temperature and rich foodstuffs in May, it gradually spreads to the leaves, branches, fruits and stems. Hazard, from June to August is the peak of the 4th to 8th generation, the density of larvae is the highest, and it is highly concentrated on sucking fruit juice and breeding in the pupa, and the larva density decreases after August.
At first, the fruit was damaged. At the beginning, there were piles of yellow powder on the fruit surface. When you looked at the eggs and the newly hatched nymphs, you wiped off the yellow, slightly depressed patches on the surface. This is the nymph damage. When the fruit is nearing maturity, it is often clustered around the loquat to suck fruit juice, and the victim is black and rot, resulting in a lot of falling fruit. The mature varieties in the mid-maturity, late-maturing varieties and white pear systems that matured from late August are the most affected.
Fourth, control methods
(a) In the middle of December in winter, the Qingyuan sterilizing machine was used to scrape the trunk and the large branches of the rough skin and burn them centrally. And carefully spray a 3 ~ 5 degrees lime sulfur mixture, coated white trunk, culling in the winter fruit and fruit branches and branches of the overwintering eggs in order to reduce the source of insects the following year, which is the key to prevention and control every year.
(b) Dangerous bagging pears, yellow-yellow bugs, mostly from the top of the fruit bag and the bottom of the drainage hole to climb into, so when the top bag into the fruit bag to be tightly sealed, the bag to bulge straight, the lower drainage hole To face down, to reduce the yellow fly into the bag.
(3) In the month of the overwintering eggs hatching in March, the nymphs began to migrate in May, and each sprayed a pesticide to cull the early stage nymphs; in the peak period of July to August, every 10 to 15 days, combined with the control of other pest sprays The drug once, even spray 4 to 5 times. The pharmaceutical composition may be 80% powdered mancozeb 800 to 1000 times + 25% fenpropathrin 2000 to 3000 times, or 40% cream Dupont Star 800 to 1000 times + 2.5% deltamethrin 2500 to 3000 Dilution, or 70% powder thiophanate-methyl 1000-1200 times +5% cream pyrimidine 2500-3000 times. The medicine should be used for rotation. Do not spray a combination or a pesticide the next time, so as not to increase the resistance of the insects. After bagging, do not use the solution bag to spray the medicine. Spray only the outside of the fruit bag until it drops without drip. When the medicine effect penetrates into the bag, the insect can be extinguished.

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