Vegetable aphid damage
There are a variety of vegetable aphids, including turnip aphid and cabbage aphid, Myzus persicae, Myzus persicae, bean aphid, Aphis gossypii, the turnip aphid, cabbage aphid, tobacco vegetables. Diaeretiella 1 years about 20 generations, often clustered in dense leaves were back, taking vegetable juice, causing serious plant dehydration and malnutrition, the slow growth, victims of serious stagnation of growth. Leaves after the murder, showed curled, yellowing, deformation; deformation stems, pedicel and other victims, strong influence. In addition to the direct damage of vegetable aphid, a large number of insect honeydew excretion, both yield and reduce the quality of vegetables. In addition, aphids are mainly spread virus disease, which can be in a short period of time will be infectious virus from infected vegetables to healthy plants, the disease caused by the virus transmission loss is not lower than the damage of aphid.
The winter in protected areas and continue to harm vegetable greenhouses in the area; in the open field vegetables (Chinese cabbage) to overwintering eggs or parthenogenetic aphids, and part of the winter in overwintering spinach. The following year 3~4 months of egg hatching, breeding several generations after overwintering parasitic aphids, and then moved to cruciferous vegetables, and then gradually spread to Solanaceous Vegetables or other vegetables, the formation of the damage peak in spring. The summer due to rain, high temperature, natural enemies, not conducive to the occurrence of aphid, harm is relatively light; in late August with the temperature gradually decreased, the rain reduced, suitable for aphid reproduction, autumn peak formation damage. Therefore, the fall is an important period for aphids control. In October the number of alate moved over the winter host damage and produce sexual reproduction, mating and oviposition of overwintering aphid.
2005~2008, to investigate the occurrence of vegetable aphids, found that the occurrence and damage of aphid increased population density also increased year by year, especially in the autumn of 2008 Qiucai seedling damage, Sada rate of 100%, the average aphid strain rate above 60%, the average number of aphid 500~800 per hundred plants, up to 10 thousand head per hundred. The occurrence of vegetable virus disease was more serious, which had a great influence on the growth and development of Chinese cabbage and radish, and the yield loss reached 20%~30%.
Causes of vegetable aphid reproduction
1, extended host range, long duration of harm
In recent years, with the increase of vegetable varieties, the area of protected land expanded, from 0.5hm2 in 2000 to 2hm2 in 2008. Vegetable varieties increased from 10 to more than 30, to provide adequate food source and overwintering sites to aphid, aphid in overwintering stage before the winter months, but with the development of protected areas, were no longer winter but continue to damage, and the occurrence of a large number of. Occurred in spring and autumn, all varieties of vegetables spared; in addition, excessive application of nitrogen fertilizer, vegetable too shade, also caused serious occurrence of aphids.
2, large appetite, fast reproduction rate
The aphid and aphid nymphs are sucking the sap feeding on host plants. According to the survey, 1 headed aphid 24h weighed 8 times its weight. Aphid fecundity per female aphid is very strong, life can be litter aphid around 70, when the food is plentiful, wingless aphid amount is larger, and the cluster damage; when the lack of food or environmental conditions are not timely, there will be a large number of aphids, and spread out damage, resulting in large losses.
3, strong resistance, difficult to control, put a large investment
According to the survey, Aphids Control and dosage, investing investment accounted for more than 50% of the whole vegetable pest control. Because of large dosage and frequent prevention and cure, human and livestock poisoning accidents also happen frequently.
4, natural enemy control is poor
Influence of aphids from their natural enemies, such as the number of Aphidiidae, ladybirds, lacewings, syrphids and other large predators field, have a certain inhibitory effect on aphid. But because the farmers blind application, see the insect spray on aphid enemies damage, the loss of natural aphid control.
5, the influence of temperature and humidity on the occurrence
From the observation in recent years, the temperature and rainfall have a great influence on the occurrence of aphids. The temperature at 20~25 C is good for the occurrence and damage of aphids, and the temperature over 30 DEG C inhibits the occurrence of aphids. If winter drought, high temperature, then the next spring heavy, summer high temperature, high humidity weather on aphid adverse. If autumn is dry, it will cause serious damage in autumn.
Method for controlling vegetable aphid
1. agricultural control. In the farming system, crop rotation is practiced and continuous cropping is avoided. In the previous crop harvested vegetables, timely plowing, drying ridges, clearing the field debris, in order to reduce the source of aphids. Aphid eating carbohydrates, in vegetable cultivation process, to make more use of rotten farmyard manure, to minimize the use of chemical fertilizer, especially can't avoid too much fertilizer, vegetable leaves too green and leggy. If the plant has a rapid increase in carbohydrates, the aphid will develop in a short period of time.
2. natural enemy aphid control. Many aphid species of natural enemies, mainly ladybugs, Harmonia axyridis, grass clams, syrphids and aphid fungi, pay attention to the protection of these beneficial natural enemies and be used to eliminate a large number of aphids, the aphid population control in large area within the number is not enough to cause damage. When there are not many aphids and natural enemies in the field, do not use pesticides, so as to avoid harming natural enemies and destroying the ecological balance. When the aphid damage reaches the control index, it is necessary to use the medicine in the injured part of the plant, such as the growth point, the young leaf, the young stem and the dorsal lobe of the plant, so as to achieve a definite aim and fully protect the natural enemy.
3. yellow aphid. Alate aphids have a strong response to yellow or orange color, can be made of 15 cm x 20 cm in size in the production of yellow cardboard, cardboard and coated with a layer of No. 10 oil or cure aphid commonly used pesticides, yellow cardboard inserted or hanging flat in vegetables and vegetables at the top row. Oil yellow aphid induced full time after the replacement, the drug can make the medicine that yellow aphid touch dead.
4. silver gray film to avoid aphid. Aphids have a strong aversion to silver grey. They may hang some silver gray plastic strips in the field or cover vegetables with silver grey film.
5. urine washing mixture to eliminate aphids. The urea, washing powder and water according to the ratio of 4: 1: 400. Urinary wash mixture, evenly and carefully sprayed on the leaves of the pros and cons, spraying liquid 60 kg per mu, even 2 to 3 times. Spraying urine washing mixture not only has better control effect on vegetable aphids, but also has the effect of leaf fertilizer promoting growth. But the urine washing mixture should be used now, so as to prevent the volatilization of urea.
6. aphid elimination by plants. (1) tobacco ground into fine powder, add a small amount of lime powder spreading; (2) pepper or wild Artemisia soaked in water for a day, after filtering spray; (3) castor leaves after crushing the applicator, or with water at a ratio of 1 to 2 after soaking for 10 minutes, filtering spray; (4) leaves soaked in water for a day, adding a small amount of lime, filtering after spraying.
7. plant aphids. For example, the volatile smell of leek has a repellent effect on aphids, so planting leek with other vegetables can reduce the density of aphids and reduce the damage degree of aphids to vegetables.
8., the pig bile fluid to destroy aphids. Adding baking soda or washing powder in pig bile liquid 10%, directly sprayed on by aphids, Pieris rapae harm on the vegetable plants, can effectively kill pests. The diluted liquid can remain unchanged for 10~12 days.
9. lime powder to kill aphids. The lime powder sprinkled on aphids on leaves, aphids will soon be killed.
