Xuan papaya is a famous Chinese medicinal herb that attracts many farmers to grow it. However, in the process of xuan papaya planting, xuan papaya aphids eroded the healthy growth of xuan papaya, which damaged the interests of farmers' uncles. So, what are the reasons for the serious harm of xuan papaya aphids? How to control papaya aphids?
<h1 class = "pgc-h-arrow-right" >1, aphid harmful symptoms and life habits</h1>
1.1 Peach aphids
Peach aphid, also known as peach aphid, smoke aphid, this insect is widely distributed, occurs on papaya trees throughout the year, and also endangers peach, plum, pear, plum blossom, cherry blossom, moon season, oleander, caryophyllus, snapdragon, dahlia, chrysanthemum, cyclamen, poinsettia, melon leaf chrysanthemum, etc. and a variety of cruciferous plants. Adults and nymphs mostly gather on new shoots and young leaves to suck plant sap, causing longitudinal curling and shrinking of new shoots and young leaves, and secreting a large amount of aphid dew, causing the occurrence of coal pollution disease.
The wingless female aphids of the peach aphid are green, sometimes yellow to reddish brown, compound-eyed, with a long, cylindrical tube. Winged females have a black head , a black thorax , and a dark brown belly. The eggs are oblong and oval, pale green at first and later pitch black. If the aphid is similar to the wingless female, it is small.
Aphid la occurs for more than 20 generations, with eggs or wingless fetuses born female aphids in the papaya winter aphids and autumn germination of young shoots and vegetables, crops on the back of the leaves of the overwintering, early March of the following year overwintering eggs and overwintering females develop into "dry mothers" for asexual reproduction, and constantly produce winged aphid spread hazards from the end of May to the beginning of June to fly to the forest and the surrounding summer host tobacco or other crops, vegetables for harm, September to November and then gradually moved back to papaya, peach, pear, plum and other fruit trees to produce sexual aphid mating, spawning, overwintering.
1.2 Peach aphid
Peach tumor aphid, also known as peach tumor aphid, the distribution range is similar to that of peach aphid, the host plant in addition to Xuan papaya, there are peach, plum, pear, cherry, plum, ai and other grass plants. Adult insects in the early leaf development stage of Xuan papaya began to harm, its hazards are basically similar to the former, the first young leaves longitudinally rewind, the young shoots curled and shrunk, and then the leaves appeared albino thorn suction point, and then the entire leaf withered and fell off, the new shoots could not grow, resulting in fruit fall, deformity and yield reduction.
The winged female aphid is 1.8 mm long, with a wingspan of 5.1 mm, light yellowish brown, the frontal tumor is pronounced, inclined inwards; the antennae are filamentous 6 segments, slightly equal to the body length, the third segment has more than 30 sensory circles, the 6th section is whip-like 3 times the basal length; the abdominal canal is cylindrical, slightly expanded in the middle, with black tile-like stripes; the caudal cone is conical, the middle is constricted; the wings are transparent, the veins are yellow; and the legs of the feet, the ends of the tibia, and the tarsal nodes are darker in color. Wingless females are about 2 mm long, with a black head and russet eyes; small nodular protrusions on both sides of the middle thorax; black markings on the back of the abdomen; dark green, yellow-green, or yellow-brown body; frontal tumors, abdominal tubes, and tail patches are the same as those of winged female aphids. Oval, black. If the aphid is similar to the wingless female, the body is small, pale yellow or light green, the head and abdominal tube are dark green, and the compound eyes are vermilion; the winged aphid has a well-developed thorax and winged buds.
The pest can occur in southern Anhui 1a for more than 20 generations, with eggs and female aphid nymphs overwintering at the cracks in the base bud axils of papayas, overwintering eggs hatching into "dry mothers" in early March for asexual reproduction, when the new shoots of Xuan papaya germinate, branches and leaves begin to endanger, from the end of April to mid-May, winged aphids are produced, most of them migrate to the forest and surrounding crops, and from September to October, they return to Xuan papaya or other fruit trees to harm and lay eggs for overwintering.
<h1 class="pgc-h-arrow-right" > the cause of aphid damage</h1>
The occurrence of this insect is not only related to the adjustment of the planting industry in recent years, but also related to cultivation and horticulture. Among them, excessive application of nitrogen fertilizer is one of the main reasons for the serious harm of aphids. Excessive nitrogen fertilizer and partial nitrogen fertilizer induce a large number of papaya pumping: sub-tender shoots, newly colonized papaya seedlings and new shoots have a prolonged growth period, and the tenderness index in the field of papaya gardens has increased, making papaya trees an important summer host for aphids, and the harm of aphids has shown an upward trend.
<h1 class= "pgc-h-arrow-right" > control of two aphids</h1>
3.1 Improve cultivation techniques
(1) Reasonable fertilization. Increase the application of organic fertilizer, rational application of ammonia, phosphorus, potassium fertilizer, to prevent the application of nitrogen fertilizer caused by 2 times of shoots and tree growth. (2) Improve fertilization methods to promote the growth of strong spring shoots. The base fertilizer was completed in advance to November, the amount of use accounted for 80% of the total, mainly organic fertilizer, combined with ternary compound fertilizer application; germination fertilizer was applied early to mid-February, mainly nitrogen fertilizer, attacking spring shoots, promoting early onset and early maturation.
3.2 Forestry measures
(1) In view of the wide range of aphid hosts, especially for a variety of fruit trees and crops, we should try to avoid mixing with other fruit trees in afforestation design to reduce their transponder; (2) avoid planting cruciferous crops such as melons, beans, tobacco leaves, rapeseed, radishes and other cruciferous crops in the forest; (3) In the winter management of papaya forests, combined with pruning to cut off autumn shoots and young leaves, scrape off disease spots, warped skins, coarse skins, remove dead branches, fallen leaves, weeds, root necks, root tillers, remove insect eggs and female aphids wintering sites. (4) Remove dead branches and leaves from the ground and burn them intensively and deeply overturn the tree tray, destroy the dead branches and leaves, so as to reduce the source of overwintering diseases and insects.
3.3 Protection and utilization of natural enemies in the forest
Tian Fangxin et al. (2005) surveyed the arthropod community of Xuan Papaya Garden and found that there are more than 20 kinds of predatory predators in the papaya forest, such as ladybugs, grass worms, ants, aphids and wasps. Give full play to the control role of natural enemies, can effectively control the harm of aphids. Therefore, when carrying out chemical control, we should pay attention to protecting natural enemies, and try to choose to use low-toxicity pesticides for prevention and control in winter and early spring after the beneficial insects are stung and dormant.
3.4 Chemical control
For the selection of prevention and control agents, protective agents and chemical agents with low toxicity and low residue should be selected as much as possible in the principle of prevention.
(1) In combination with the prevention and control of papaya diseases in winter, stone sulfur compound 3 to 5 degrees spray control is used, and the main trunk is painted with white coating agent protection.
(2) During the growing season of papaya, biological pesticides such as bitter tobacco emulsion oil and sodium thirrhilate can be used for spray control, and chemical pesticides should be used with caution. When the density of the insect mouth is indeed large and difficult to control, the insect mouth can be lowered by spraying imidacloprid, aphid net or anti-aphid detergent 1 month before the papaya is ripe for picking.
(3) The use of fungal insecticides can be considered. At present, the application of fungal insecticides is of great significance in the pollution-free control of pests.
Xuan papaya, a specialty of Xuanzhou District, Xuancheng City, Anhui Province, is a national geographical indication for agricultural products. Has a high market value and economic value. Therefore, improving the planting of Xuan papaya with quality and quantity can greatly enhance the economic benefits of growers. The harm of Xuan papaya aphid is a common pest in xuan papaya planting, scientific and effective control, can achieve better control effect, provide farmers with benefits.