Pest control is one of the main contents of garden plant cultivation and conservation. The common diseases of oxalis purpurea are leaf spot, root rot and gray mold, and the pests are tetranychus cinnabarinus, rock mite of oxalis purpurea, tobacco thrips, peach aphid, North China mole cricket, identical snail and wild slug. The causes, symptoms, characteristics and laws of the disease and its prevention and control measures are as follows.
leaf spot
1. Symptoms
Leaf spot damages the leaves of oxalis purpurea. At the time of onset, the leaves produce lavender water-stained irregular spots, some of which
Oxalis purpurea (4 sheets)
There are obvious edges and clear boundaries with healthy parts; The others are not clear. After the lesion turns yellowish brown, it gradually expands, the center turns gray and the edge turns brown. After several lesions merged, the tissues between the lesions turned yellow and died. When wet, black powdery mildew layer is produced at the diseased spot. Seriously damaged leaves will dry up and curl.
2. Relevance Law
In the growing season, Oxalis purpurea leaves grow intensively, and the lower part is poorly ventilated and light-permeable. Over-dense planting is prone to leaf spot disease. The diseased plants and plant residues in the soil are the wintering places for pathogenic bacteria. With the help of airflow and rain, conidia spread, and the high temperature and humid environment is conducive to the spread and spread of diseases. They invade oxalis purpurea from stomata or wounds. Diseases can occur from the beginning of May to the beginning of September, and can occur in the greenhouse all year round. When the temperature is 24-35℃ and the relative humidity is above 90%, the disease is the most serious, especially in rainy season. Soil continuous cropping is a serious disease.
3. Preventive and control measures
(1) agricultural control: strengthen field management, combine with shaping and pruning of oxalis purpurea, and promptly remove infectious sources such as diseased leaves, residual leaves and dead leaves in the nature reserve. Avoid continuous cropping as much as possible and take rotation for more than two years. Strengthen cultivation and maintenance, reasonably fertilize water, pay attention to ventilation and light transmission, and keep the soil humidity moderate.
② Chemical control: at the initial stage of the disease, 70% thiophanate methyl 1000 times solution and 500% carbendazim solution were alternately sprayed on the leaves of oxalis purpurea, once every 7- 10d, and continuously for 2-3 times. You can also mix 3kg of plant ash with quicklime powder 1kg and spread it, with 40-60g per pot, which has obvious control effect on leaf spot of oxalis purpurea.
root rot
1. Symptoms
Root rot damages the roots and bulbs of oxalis purpurea. Damaged plants wither in the daytime sun and arrive at night.
Oxalis purpurea (2 sheets)
Recover in the early morning. The initial symptom is that the leaves of Oxalis purpurea show a similar state of fertilizer deficiency and purple; The roots withered; Less fibrous roots, light yellow brown; The taproot has no obvious symptoms. With the aggravation of the disease, the plant grows worse and worse, the leaves begin to turn yellow and wither, the fibrous roots rot completely, and the main roots turn dark brown and rot gradually; After extrusion, the root cortex is easy to peel off; Black-brown mold layer and glue can sometimes be seen at the base of bulb. Finally, the water shortage of plants intensified, and all the leaves of Oxalis purpurea withered and the plants died. This disease is not easy to be found at an early stage.
2. Relevance Law
Pathogens overwinter in soil and on the remains of diseased plants. Pathogens invade oxalis purpurea from the root wound, and then produce conidia in the affected area. With the help of rain or irrigation water, it spreads, spreads and reinfects. High temperature and high humidity environment is conducive to its onset. The occurrence of diseases is closely related to cultivation management besides environmental conditions. The diseases are often more serious because of inadequate soil disinfection, local low-lying water accumulation, immature fertilizer use, underground pests or agricultural operations that damage the roots. Generally, it is more serious in high temperature season, and it is easy to happen when the soil water content is high.
3. Preventive and control measures
① Agricultural control: Clean up the cultivation site in time, apply fertilizer and water scientifically, prevent flooding and keep the soil moisture moderate. Before Oxalis purpurea was cultivated, several fungicides were alternately sprayed on the substrate for multiple disinfection. Pentachloronitrobenzene or formalin can be used for disinfection. Remove and destroy the diseased plants in time. Root rot fungi are anaerobic bacteria. It is an effective control measure to loosen soil 1 time within 3-5 days after Oxalis purpurea is planted to enhance soil permeability.
② Chemical control: 500-fold solution of 50% thiophanate-methyl and 500-fold solution of 50% carbendazim were sprayed at the initial stage of onset. After the onset of the disease, the roots can be irrigated or sprayed with 700 times solution of 50% deuterium alcohol, 50% thiophanate methyl/0/000 times solution, 65% dicisone 600-800 times solution and 75% chlorothalonil 600 times solution.
gray mold
1. Symptoms
Gray mold harms the leaves and bulbs of oxalis purpurea. Yellow-brown waterlogging spots (such as scalding by boiling water) appear on the leaf edge or leaf angle of the injured leaf, and continue to expand and sink inward, making the leaf dry; Brown patches appeared after the bulb was damaged. When the temperature and humidity are suitable, the diseased spots quickly spread around, and the diseased parts are easy to rot and break from the infected parts. When the air is humid, the surface of every diseased part is densely covered with a gray mold layer, which is the conidiophore and conidia of pathogenic bacteria. In the late stage of the disease, sclerotia can be seen in some parts of the disease. When the disease is serious, the whole Ye Quan strain dies.
2. Relevance Law
Botrytis cinerea adheres to diseased plant residues through mycelium, conidia and sclerotia, or stays in the soil for the winter. Not only in early spring,
Oxalis purpurea (3 sheets)
It appears in late autumn or winter and is popular in low temperature and high humidity. When the temperature is 18-25℃ and the relative humidity is above 90%, the disease can occur within 1-2 days. The development temperature of botrytis cinerea is 4-32℃, and the growth, development and reproduction of botrytis cinerea stop above 32℃. In humid summer, if it is cloudy for several days in a row, it is also prone to gray mold. The environment with excessive temperature difference between day and night and poor ventilation is suitable for the growth and reproduction of bacteria. Oxalis purpurea is planted too densely, and potted flowers are placed too densely, which leads to serious diseases when sprayed with water.
3. Preventive and control measures
① Agricultural control: strengthen field management, reasonably close planting, and ensure ventilation and light transmission among plants; Water scientifically, control watering after onset, and spray around leaves and bulbs when necessary. The greenhouse should be ventilated in time, and the humidity should be reduced below 80%, especially when the temperature rises in sunny days after cloudy days. When planting, apply sufficient base fertilizer, apply decomposed organic fertilizer as far as possible, increase phosphorus and potassium fertilizer, control the amount of nitrogen fertilizer, keep plants strong and improve disease resistance. Dead leaves should be removed in time, and high-temperature composting or deep burial should be concentrated. At the end of the growing season, plant residues should be cleaned up to reduce the places where germs live.
② Chemical control: spray powder in windless close planting plot or closed greenhouse, and use 5% chlorothalonil composite powder and 6.5% wanjunling 9- 10d 1 time, or use it alternately with other methods for 2-3 times. When spraying powder, aim at the top of oxalis purpurea, and the spraying effect is better in the evening or after rainy days. Before the rainy season or early onset, it can be controlled with 800 times of 50% mirex, 500-800 times of 50% carbendazim and 800- 1000 times of 70% thiophanate-methyl.
Tetranychus cinnabarinus
1. Morphological characteristics
Tetranychus cinnabarinus pest
Tetranychus cinnabarinus belongs to Acari Tetranychioidea, also known as red spider. The adult body color of Tetranychus cinnabarinus changed greatly, but most of them were rust red or crimson. Female mites are 0.4-0.5 mm long and pear-shaped; The male mite is about 0.3mm long and its abdomen is conical, wedge-shaped and brown. Oval, white, transparent; The larvae are round, yellow at first, and turn brown-green after feeding.
2. Occurrence regularity
Tetranychus cinnabarinus occurs every year 12- 15 generations. In autumn, female adults congregate in dead leaves, rhizosphere of weeds, clods or cracks in bark, and leave the wintering place to feed and lay eggs after recovery in early June of the following year. Oxalis purpurea can also be harmful in greenhouse in winter, with more generations. Temperature and humidity have great influence on the density of Tetranychus cinnabarinus. When the temperature is 25-30℃ and the humidity is 35-55%, the pests are the most serious. The peak period of this mite is from mid-June to mid-August, and it is from March to June and from September to June in greenhouse+0165438+1October. Therefore, the high temperature and dry environment is the main factor for the rampant tetranychus cinnabarinus. Low temperature rainstorm in early spring and heavy rainstorm in summer and autumn can obviously inhibit its growth, development and reproduction, and reduce its population density.
3. Hazard characteristics
Tetranychus cinnabarinus mainly harms the leaves of oxalis purpurea, followed by sepals and flowers. Tetranychus cinnabarinus likes to live on the back of leaves.
Oxalis purpurea (3 sheets)
Sucking the juice of oxalis purpurea with a stinging mouthpiece, yellow-white or yellow-green spots appeared on the front of the leaves at the early stage of the injury. Check the back of the leaves, you can find insects, eggs, silk screens and secretions. In severe cases, the whole leaf is brown and burnt, and there is a screen on the back of the leaf. Later, it gradually spread to the whole leaf, causing the leaves to turn yellow and wilt. When a large number of netting hazards occur, the growth of plants will stagnate, leaves will fade, wither and turn yellow, and even plants will die.
4. Preventive and control measures
(1) Agricultural control: Oxalis purpurea has many leaves, so it should be pruned in time to thoroughly remove the dead flowers, leaves and surrounding weeds, reduce insect sources, increase humidity and worsen the living conditions of Tetranychus cinnabarinus. Strengthen daily maintenance management, and when yellow-white or yellow-green spots appear on leaves, remove them and destroy them centrally.
② chemical control: when the temperature rises in April, 40% dicofol EC 1000- 1500 times and 20% triadimefon 500-800 times should be sprayed, and it is impossible to control tetranychus cinnabarinus in a large area. Oxalis purpurea grown at home can be used as a homemade insecticide. Boil 50 grams of tobacco leaves and 500 grams of clear water for 30-40 minutes, remove residues, take clear liquid and spray. You can also use garlic extract or red pepper to boil and filter, and spray with 1∶500 times solution, which has a good control effect on tetranychus cinnabarinus, especially on tetranychus cinnabarinus and other small mites.
③ Biological control: protect the natural enemies of Tetranychus cinnabarinus, such as Chrysopa sinica, Chrysopa magna, Chrysopa maculata, stinkbug maculata and Tomicus Gao Qiao. And control cinnabar.
Peter robbia Hattie
1. Morphological characteristics [1]
Oxalis purpurea (2 sheets)
Rock mite of oxalis oxalis
Rock mites of Oxalis belong to Acari Tetranychioidea, also known as Oxalis such as Tetranychidae. The female mite is 0.7 1mm long and 0.49mm wide. Oval body, crimson; Feet are slender, about twice as long. Male mites are 0.35 mm and 0.22 mm in length; Wide. The body color is orange and yellow, and there are obvious black spots on both sides of the back; The length of the foot is almost three times the length of the body.
2. Occurrence regularity
Rock mites of oxalis occur for many generations every year, and females overwinter in the gaps in the soil near the rhizosphere of oxalis purpurea. There are two insect population peaks in early summer and Mid-Autumn Festival. Most eggs are laid on the back of Oxalis purpurea leaves, and a few are laid on the front and petiole of leaves. There is a habit of crossing the summer. When it is rainy and cold in autumn, it is harmful to return to plants to feed. Young and adult mites suck leaf juice in leaf backstab. The damaged leaves are yellow-white or yellow-green, with small spots. In severe cases, the leaves will turn yellow, wither and even wither. Rock mites in oxalis do not form a network, but they are harmful to the front and back of leaves. In the same pest period, eggs, young mites, nymphs and adults coexist.
3. Hazard characteristics
Rock mites of oxalis mainly harm the leaves of oxalis purpurea. This kind of mites gather on oxalis purpurea, which often leads to the yellowing of oxalis purpurea, even burning or leaving only a few petioles, which seriously affects the normal growth of oxalis purpurea. Plants with high population density and early occurrence will zoom in late May, and most of oxalis purpurea will turn yellow from early June to late July. Oxalis purpurea is yellow and leafless in summer because of the harm of this mite and the high temperature and dry environment. In the same oxalis purpurea plant, the rock mite of oxalis first damaged at the edge and then spread to the middle of the plant.
4. Preventive and control measures
Chemical control should be adopted for the rock mite of oxalis oxalis, and the control effect is better with 50% monocrotophos EC and 40% dimethoate EC 1500 times solution. The general contact acaricide is basically ineffective, because Oxalis purpurea plants are low, it is difficult to spray pesticides on the back of leaves, and Oxalis purpurea, a rock mite, cannot contact pesticides. Monocrotophos is highly toxic, so pay attention to safety when using it. In order to reduce the pollution to the environment, it is suggested that the prevention and control of rock mites in oxalis oxalis should seize the spot occurrence stage, that is, before the harm of rock mites in oxalis oxalis spread, drugs should be sprayed in and around the center. Because the generations of this mite overlap and there are many eggs in the population, it should be sprayed several times in succession, with an interval of about 7 days each time. In addition, we should pay attention not to use a single variety of pesticides for a long time, so as not to induce the resistance of mites.
Tobacco thrips
1. Morphological characteristics
Harm of tobacco thrips
Tobacco thrips belong to Thysanoptera (Thrips), also known as onion thrips. Tobacco thrips are tiny, with a body length of 1. 1- 1.3 mm; The body color changes greatly, mainly black, brown or yellow; File suction device; Linear 6-9 node antenna; The wings are long and narrow, and the hair on the edge is long and neat; Claw degeneration.
2. Occurrence regularity
In greenhouse, thrips tabaci has more than 12 generations per year, and scattered eggs are laid under the epidermis and veins of leaves, which has strong reproductive ability. Adults and nymphs lurk in soil crevices, clods, litter, field bulbs and leaf sheaths of some plants, or overwinter in the soil in a "pupa" state, but adults overwinter mainly. Activities will start in March-April of the following year. Dry and rainy environment is beneficial to the growth, development and reproduction of thrips tabaci, while high temperature, high humidity or heavy rain will inhibit its activities. Because of the fear of light, thrips often climb to the surface of leaves in the morning and evening when it is cloudy and humid, and feed on the back and veins of leaves in sunny days. Adults are active, can fly, jump and spread.
Spread quickly.
3. Hazard characteristics
Tobacco thrips do harm to the leaves and flowers of oxalis purpurea, and the harm is more serious. Tobacco thrips file through the epidermis of plants with a file suction mouth and suck their juice. Adults and nymphs mainly harm petioles and veins. After the young leaves are injured, the leaves are twisted, deformed and stunted; After the leaf is injured, faded purple, yellow or brown stripes will appear on the front and back, with micro-spots, and the leaf tissue will become thick and brittle, resulting in leaf withering; When the flowers are damaged, discoloration spots will appear. In severe cases, the growth of plants will stagnate, decline and die.
4. Preventive and control measures
(1) Agricultural control: irrigate and spray water in time, thoroughly remove plant residues and weeds in the field and surrounding areas, dig deep into the soil to break pupae before winter, and reduce the base number of tobacco thrips.
② Physical control: Trapping and killing thrips tabaci with blue water tray or blue sticky buckle plate.
③ Chemical control: 50g of 10% imidacloprid and 250g of water were selected and sprayed on the back or center of the leaf twice in the morning and evening. Spraying 40% omethoate, 50% chlorpyrifos and other internal absorbents 1000 times, omethoate affects the color, so use it with caution. The control effect of using thrips whitefly net EC is also good.
④ Biological control: Protecting and utilizing the natural enemies of tobacco thrips, such as stinkbug, stinkbug, striped rice borer, etc., plays a significant role in inhibiting the population growth and decline.
Myzus persicae
1. Morphological characteristics
Myzus persicae belongs to Homoptera Aphidoidea, also known as Aphidoidea. Myzus persicae is small, with black head and chest, six antennae, green, brown, yellow-green or reddish brown abdomen and light black stripes on its back. The autumn migration of male aphids is similar to that of female aphids, and the black spots on the abdomen are bigger. Eggs are oval, yellow-green, black and shiny.
2. Occurrence regularity
In northern China, Myzus persicae can produce more than 10 generations a year, and its life history is complicated. Some are semi-periodic (staying behind) and some are full-periodic (moving). The semi-periodic peach aphid overwinters in vegetable pits or greenhouses with eggs or viviparous females in the north. Myzus persicae overwinters in branches, bud axils and cracks of Rosaceae fruit trees in winter, and overwintering eggs hatch and feed in the middle and late April of the following year, which harms oxalis purpurea. Temperature higher than 28℃ or lower than 6℃ and relative humidity higher than 80% or lower than 40% are unfavorable to the development and reproduction of Myzus persicae, and the number of Myzus persicae decreases. High temperature and heavy rain in summer can inhibit Myzus persicae. The winged peach aphid tends to be yellow, followed by green, and negatively tends to be silver-gray.
3. Hazard characteristics
Myzus persicae gathers on the tender leaves and buds of oxalis purpurea, which harms flowers and leaves in turn with the opening of buds and the unfolding of tender leaves. Myzus persicae pierces plant tissues with sucking mouthparts to absorb juice, causing yellow spots or black spots on the damaged parts, wrinkling of damaged leaves, abnormal growth, atrophy of flower buds, and even death of plants in severe cases. Myzus persicae will secrete honey dew, which will lead to bacterial growth and other diseases. In addition, it can also form galls.
4. Preventive and control measures
(1) Agricultural prevention and control: combined with garden tending and maintenance management, clean the protected land, eradicate weeds, cut off residual flowers and leaves, pay special attention to cutting off insect leaves, and occasionally pull out insect seedlings to prevent the spread and spread of pests.
② Physical control: yellow dishes or yellow plastic sheets can be used to trap and kill winged peach aphids; Placing aluminum foil strips or covering them with silver-gray plastic film in the border or greenhouse has obvious effect of avoiding aphids.
③ Chemical control: 40% dimethoate EC 50ml and 50% malathion EC 50ml and 40kg can be selected for spraying at the initial stage of peach aphid damage. You can also choose 50g of 10% imidacloprid and spray it with 150g of water, and the control effect is remarkable.
④ Biological control: Protect and utilize the natural enemies of Myzus persicae, such as Harmonia axyridis and Harmonia japonica.
mole cricket
1. Morphological characteristics
Harm of north China mole cricket
North China Gryllotaidea belongs to Orthoptera, also known as Lara Bee. Adults are 36-55 mm long and yellowish brown. The wings are short, the front foot is flat and powerful, there is a thorn on the inner edge of the tibiofibular joint of the hind foot, and there are two tail whiskers at the tail of the body. Oval, milky white and shiny at first delivery, then yellowish brown.
2. Occurrence regularity
North China mole cricket occurs about 3 years 1 generation, overwinters in soil with adults and nymphs over 8 years old, sometimes as deep as 150cm. In April-May of the following year, they began to feed. North China mole cricket is large in size, poor in flying ability, fond of sweet and rancid organic matter, horse manure and moist soil. North China mole cricket lurks during the day and comes out at night, and the peak of active feeding is 2 1-22. Soil texture is also related to insect population density. In saline-alkali land, insect population density is high, followed by loam and clay.
3. Hazard characteristics
The feeding habits of North China Gryllotalpa are very diverse. Both adults and nymphs move in the soil, feeding on the bulbs and young leaves of oxalis purpurea or biting off the seedlings, and the roots of the damaged plants are messy. Because the North China mole cricket passes through the surface, many tunnels are formed to separate the seedlings from the soil, and the seedlings often dry up and die due to water loss.
4. Preventive and control measures
① Agricultural control: North China Gryllotalpa is not resistant to flooding, and irrigation will force adults to emerge from the soil, making it easy to kill. Avoid applying immature organic fertilizer. Find the insect nest of North China Gryllotalpa and kill the eggs and females together.
② Physical control: Using the phototaxis of North China Gryllotalpa, a black light lamp was set to trap and kill the adults when they emerged.
③ Chemical control: First stir-fry 5 kg of chaff, wheat bran, bean cake, cottonseed cake or corn crumbs, then use 0. 15 kg of 30-fold solution of 90% trichlorfon, add appropriate amount of water, and mix well to a certain extent, and the effect will be better in the windless and sultry evening. You can also use 40% dimethoate EC 10 times solution or other pesticides mixed bait.
Similar to snail
1. Morphological characteristics
Homologous snails belong to the order Gramineae, also known as buffalo. The snail shell is oblate, solid and thick, with a yellowish brown or reddish brown shell surface and a horseshoe-shaped shell opening. Elliptical and spherical, milky white and shiny. Young shellfish are small in size and similar in shape to adult shellfish. Its mouth is on the ventral surface of its head, and it has a toothed tongue with many small teeth arranged neatly on it for chewing and grinding food.
2. Occurrence regularity
Homosnail occurs 1-3 generations every year, and overwinters in the wet and dark place of greenhouse. The shell mouth is closed with a white film. In the north, the same type of snails that wintered generally began to feed in early March of the following spring, and gradually turned to wintering in late September. The spawning period of identical snails is May-June and August-September, which mostly occurs in wet and loose soil cracks, grass roots, dead leaves or stones. When the soil is dry or the eggs are exposed to the ground, they cannot hatch, and the eggs on the ground are easy to burst under the sunlight. Snails of the same type like warm, dark and humid environment. It goes out during the day and eats at night or early in the morning. On rainy days, it lives on plants or in the shade all day.
3. Hazard characteristics
The same snail feeds on the leaves and petioles of oxalis purpurea. Adult and young shellfish scrape the leaves and petioles of oxalis purpurea with their tongues, resulting in holes or nicks. In severe cases, they eat up the leaves of plants and bite off the roots of plants, leading to lack of seedlings and broken ridges, and even destroying seeds and replanting. The wounds caused by feeding sometimes induce soft rot, which leads to the decay and necrosis of leaves, bulbs or roots. The white shiny colloid and dark green insect dung left by the place where the same snail climbed affected the photosynthesis of oxalis purpurea.
4. Preventive and control measures
(1) Agricultural prevention and control: clear the fields, cultivate and loosen the soil after the rain, remove weeds, stones, plant residues and other sundries in the fields, and destroy the habitats and spawning grounds of Oncomelania hupensis. In autumn, deep ploughing of soil caused mechanical casualties of some overwintering adult and larval shellfish, the exposed surface was pecked or frozen to death by natural enemies, and the eggs were exploded by the sun. Controlling soil moisture is the key to control the same snail. There was a lot of rain in the first half of the year, especially in areas with high groundwater level. It is necessary to open ditches in time to eliminate stagnant water and reduce soil moisture. Although manual grabbing is time-consuming, it is very effective. We insist on catching the same snail on the soil before sunrise or on cloudy days every day and leaving. We must kill it and not abandon it to prevent its eggs from hatching after its mother's death.
② Chemical control: When the same snail dives into the soil in the morning (cloudy morning), spray 1: 800 times of copper sulfate solution or 1% salt solution for control. Spraying 800- 1000 times mirex or 70-400 times ammonia water for control. It is suggested that the above drugs can be used alternately, which can not only ensure snail killing but also protect leaves, and also delay the drug resistance of the same snail. It is also effective to mix toxic soil with polyacetal, potato toxin and MIDA and spray it at night. You can also sprinkle tea seed cake powder and 8% mirex granules on the surface of rhizosphere soil, which can also prevent and control the same snail. Spraying trichlorfon, deltamethrin and lime powder around the flowerpot can effectively kill or drive away the same snail.
Agriolimax agrestis
1. Morphological characteristics
Wild slugs belong to the order Amphibidae, also known as slugs. Adult spindle-shaped, 20-25mm long and 4-6mm wide; The body surface is smooth, shell-free, dark gray, yellowish white or grayish red; Two pairs of antennae, dark black, with eyes at the end of the rear antenna; There is a mantle at the front end of the back, the edge is rolled up, there are obvious concentric growth lines on it, and the mucus is colorless; The egg is white and transparent, gelatinous and oval, and gathers in the egg sac; The larvae are light brown when they are first hatched, and their bodies are like adults.
2. Occurrence regularity
The annual occurrence of wild slugs is 1-2 generations, and adults and larvae overwinter under the wet soil of plant roots, which is harmful in spring and autumn. The air temperature11.5-18.5℃ and soil moisture content of 20-30% are favorable for its reproduction. Wild slugs lurk between the roots of oxalis purpurea and soil cracks during the day and climb out of the ground at night, which is harmful to the growth of oxalis purpurea. It has a strong hunger tolerance and cannot eat or move under food shortage or bad conditions. Wild slugs like dark and humid environment, especially in the corner of greenhouse in spring and in the environment with high plant density and poor ventilation. The peak time of feeding activities is the first light from evening to the next day. When wild slugs encounter adverse environments such as dryness and odor stimulation. It can quickly contract the abdomen and feet in the shell, secrete mucus, and form a liquid film outside the shell mouth to protect itself from adverse environment. But it has a strong tendency to contain sugar. Wild slugs are afraid of light and will die in 2-3 hours under strong light.
3. Hazard characteristics
Wild slugs are omnivorous and like to eat leaves and petioles of oxalis purpurea, forming irregular nicks, holes or dead seedlings. The damaged leaves were scraped off by feces and polluted, losing their ornamental value. The body of wild slugs carries many kinds of germs, and the wound caused by the bitten part becomes the passage for germs to invade, which will cause fungal infection and make the leaves rot.
4. Preventive and control measures
The wild slug has strong concealment, secretes a lot of mucus on its body surface, and the liquid medicine is not easy to reach the worm directly, so it is difficult for general insecticides to play their role. It is a refractory pest in potted oxalis purpurea.
(1) Agricultural control: Dig drainage ditches in the greenhouse, pay attention to drainage, reduce the groundwater level, and remove weeds in time. Cultivate weeds in sunny days, and let the eggs die on their own when they are exposed to the soil surface. Sprinkle lime powder or plant ash on the edge of the place where Oxalis purpurea is placed in the wild to reduce the humidity and create an environment that is not conducive to the activities of wild slugs. When wild slugs crawl over, their bodies will dehydrate and die.
② Chemical control: spray 100 times ammonium bicarbonate and 100 times 40% slug concentrated water agent during the slug boom. Because slugs are inactive in the daytime, the liquid medicine is not easy to be sprayed on wild slugs, and the general control effect is not ideal. Therefore, before chemical control, the ground and flowerpots in the greenhouse should be watered to increase the environmental humidity, so as to facilitate the activities of slugs and apply pesticides at night. In order to achieve sustained and effective control effect, it is necessary to carry out control for 2-3 times continuously. Taking advantage of the scent-seeking habit of wild slugs, an oily dry powder or corn meal bait containing 4% of active ingredients was prepared with snail venom, and it was scattered on the ground between flower pots or at the edge of flower pots at night to trap and kill them. Chemical control experiments show that the control effect can reach more than 85%.
Pest control of oxalis purpurea is a very comprehensive and complex work. We should take agricultural activities as the basis, give priority to prevention, eliminate the source of pests and diseases, and combine physical methods, chemical drugs and biological natural enemies for comprehensive management. Follow the principle of "early treatment, small treatment and big treatment" and eliminate pests and diseases at the early stage of occurrence, rather than waiting until oxalis purpurea is seriously damaged. \