【Author:Lao Dao Network Zhang Yanan】
Speaking of astragalus, watermelon growers should have a deep feeling, in recent years, the astragalus is becoming more and more difficult to control, especially in the high temperature season of the year, the astragalus breeding speed is fast, the resistance of conventional drugs is large, the prevention and control effect is not good, some melon farmers even spray a drug once in 2-3 days, but they still can't prevent it, they can only watch the astragalus wantonly harm but helpless.
On August 27, Zhang Pengyu, a farmer's housekeeper user from Zhoushan City, Zhejiang Province, sent a picture to consult the experts of the farmer's housekeeper app: "What are the bugs on the watermelon leaves, and how to cure them?" Let's take a look at how the experts answered the questions.
Aphids on watermelon leaves
Zhao Peiyu (Liaocheng City, Shandong Province - specializing in plant protection technology and cultivation technology)
Use methylvidine salt plus flufenacilamide nitrile spray to control aphids, green worms harmful.
Lv Shumin (Master of Crop Physiology, Henan Agricultural University, Pingdingshan City, Henan)
Key points in the control of astragalus: The spray is meticulous and thoughtful, which can reduce the base number of wintering aphids, and it will be much easier to control the number of aphids in the future. Once the leaf roll occurs, it is necessary to increase the water consumption and the sprinkler head with strong impact. Guarantee two points: penetrate and beat well.
Lv Lanhua (Liaocheng City, Shandong Province - good at watermelon, melon, cucumber and other crops)
Aphid damage, can choose 50% flufenacilnitrile water dispersion 10,000 times liquid, 75% spirant pyrithopridone water dispersion 4000 times liquid and other spray control. Cooperate with indigovirus to control the harm of vegetable green insects.
Feng Tao (Lu'an City, Anhui Province- specializing in plant protection technology and soil management)
Aphid harm, it is recommended to use 22% flufenacil nitrile 4500-6000 times liquid spray; 25% thiazide 1000-2000 times liquid spray; 80% enidyl pyridone 1500 times liquid spray; spironium ethyl ester, thiamethoxazine and other sprays; can be used alternately with the above agents for prevention and control.
Guo Xinhua (Liaocheng City, Shandong Province - good at watermelon, melon, zucchini and other crops)
Aphid hazards can be controlled by alternate sprays such as pyrithoprid furazine, bifenthrin plus imidacloprid, bifenerate plus acetamidine, acryliazine, thiamethoxazine, ethyl polycycline, etc.
Farmer butler knowledge small class - watermelon aphid
Yellow aphid is one of the highly harmful insects that has appeared in the greenhouse watermelon planting area in the past two years. Compared with ordinary pests, astragalus has the characteristics of strong explosiveness, high resistance to ordinary insecticides, greater harm, etc., when the damage is serious, the whole leaf is curled, the growth point is dead, the growth of melon seedlings is stagnant, and when it is serious, the whole plant can die in the melon seedling stage. Please be vigilant with friends who grow watermelons.
1. Harmful symptoms
Watermelon aphids use adults and nymphs to suck up sap on the back of the young leaves and on the young stems of watermelons. After the young leaves and growth points of melon seedlings are damaged, the leaves shrink, the melon seedlings wilt, and when the damage is serious, the entire leaves are curled, the growth point is dead, the growth of melon seedlings is stagnant, and when it is serious, the whole plant can be killed during the melon seedling period.
Aphids cluster on watermelon leaves
Old leaves are affected, withered in advance, shortening the melon formation period, causing the "honeydew" excreted by the reduced production of melon aphids to pollute the leaf surface, affecting photosynthesis, and can also cause soot disease, so that the quality of watermelon declines. More importantly, viral diseases can be transmitted, which can cause symptoms such as flowering, malformation, dwarfing and other symptoms in plants, and the victim plants have premature aging.
Second, the law of pathogenesis
Watermelon field aphid control is difficult, mainly occurs in the watermelon melon stage and fruit expansion stage, its reproductive ability is extremely strong, as a rampant, catastrophic pest. Melon aphids are multi-type pests that often occur in different seasons, with the hazards of aphids being particularly severe.
Watermelon aphids can occur for more than 20 generations per year, mainly overwintering with eggs. Under suitable temperature and humidity conditions, watermelon aphids can complete a generation every 5-6 days. Each female aphid can reproduce more than 50 aphids in a lifetime, and the reproductive rate is very fast. More than 10 generations occur annually in North China, 20-30 generations in the Yangtze River Basin, no diapause phenomenon, eggs on the overwintering host or in adult aphids, aphids in greenhouses overwinter or continue to breed. Spring temperatures above 6 °C began to be active, after breeding 2-3 generations on the wintering host, at the end of April, the winged female aphids were produced, from the winter host plant to the summer host plant, turning to melons, vegetables or other summer hosts to harm.
Aphids reproduce rapidly, and can reproduce a generation in 3 to 5 days, so it is necessary to control it in the early stage of harm and when the insect population base is not large. And watermelon aphid mutation coefficient is very high, very easy to appear resistance, so the same mechanism of action of the agent should not be reused, therefore, melon aphid to control the attention period, medicine, medication.
Third, prevention and control methods
Agricultural control
(1) Combine the seedlings to clean the countryside.
(2) Working next to the wheat field, so that the natural enemies such as the seven-star ladybird on the wheat field move into the melon field to hunt for aphids, which can reduce the melon
Aphid population density.
(3) In production, farmers often use tobacco water [smoke: water = 1: (30 ~ 40)] spraying, which is also very effective against aphids.
Physical control
(1) Yellow plate insect traps. For aphids with a strong tendency to yellow, they are booby-trapped by inserting yellow plates in watermelon fields. Specific method: homemade wood or cardboard, the size is (50-70) cm * 30 cm. First paint the wooden board yellow, and then use the oil with a little butter to stir evenly, apply to the wooden board, about 20 pieces per acre, inserted between the melon field plants, the cutting board should be 10-15 cm higher than the plant, when the yellow board is sticky with pests, use the above method to apply again, can be used repeatedly. It is also suitable for pests such as whitefly and American spotted diving flies.
(2) Silver gray film avoids aphids. Using the silver gray repellency of aphids, covered with silver gray film hangs silver gray plastic film around the melon field to achieve the purpose of aphid prevention.
Biocontrol
Protect and exploit predators. According to reports, the daily aphids of small black spiders, star leopard spiders and trolls are 70, 190 and 84, respectively; the number of aphids caught by larvae such as seven-star ladybugs, turtle ladybirds and black-haired ladybirds is 200-300 heads. There are also aphid flies, aphid cocoon bees, etc., which can prey on or parasitize aphids. In addition, it is also possible to artificially raise and release aphid cocoon bees for biological control of insects.
chemical control
At present, the control of melon aphids is mainly based on pharmaceutical control, but in the selection of agents, we must pay attention to the selection of pollution-free pesticides with low efficacy and high selectivity of biological agents.
1. Before or just after the occurrence of astragalus aphid, you can choose 10% imidacloprid 750 to 1500 times liquid, or 70% imidacloprid 4000 times, or 40% acetamiprid 2500 times liquid foliar spray, and the effect of adding silicone additives to the agent is better when preventing and controlling.
Alternate medications should be used to reduce the incidence of insect resistance. It is not advisable to choose anti-aphid threat, which is not good for melon aphids.
2. When astragalus outbreak, 30% imidacloprid microemulsion 600 times liquid spray can be selected, 10% flufenacilamide 1300 times, 50% pyrazinone + thiazide and isopropylvir 1000 times liquid spray can be selected.
3. Since the occurrence of aphids will cause the spread of viral diseases, please do a good job in the prevention and control of viral diseases while preventing and controlling aphids. The control agent can be selected from 2% chlormycin 750 times liquid or 5% morpholine guanidine hydrochloride 750 times.
Precautions
(1) Watermelon aphids, strong repetitiveness, easy to form resistance, should be rotated to use agents or mixed with different mechanisms of action to enhance the prevention and control effect.
(2) Grasp the medication time, should be used in the initial stage of aphids, when the aphid resistance is low, with a small amount of agent can control the occurrence of aphids, conducive to watermelon growth, is conducive to improving the quality of watermelon.
(3) When spraying the agent, even if the aphid drug can play a positive and anti-death role, it should also be done that the watermelon leaf is sprayed evenly on both sides, so that the effect will be better.