Pepper disease

Pepper Fusarium wilt, also known as chronic wilt, chronic decline disease and yellowing disease, is an important disease second only to pepper blast. In the late 1920s and early 1930s, a serious chlorosis occurred in Bangka Island, Indonesia, and 22 million peppers were lost, with a loss rate as high as 90%. India lost 10% of pepper plants due to Fusarium wilt, while Guina lost 30%, which also caused serious losses in Malaysia and Brunei. In Brazil, Fusarium oxysporum caused by rot is more serious than pepper blast, which is the biggest disease in Brazilian pepper production. In recent ten years, some pepper orchards in Wenchang, Qionghai, Wanning, Danzhou, Qiongzhong, Baisha and Ledong in Hainan Province and Zhanjiang in Guangdong Province have also suffered from pepper wilt, most of which occurred in fruit-bearing pepper orchards, and its distribution area was more extensive than pepper blast, and the loss of pepper plants caused by it was generally 5% ~ 15%, and there was an increasing trend year by year.

symptom

The common manifestations of infected plants are that the leaves fade and turn yellow, the growth is not prosperous and the plants are shortened. In severe cases, the whole plant withered and declined. The aboveground part of the diseased plant, at first, some leaves lose luster and gradually turn yellow, and then most leaves turn yellow; Some yellow leaves wilt, droop, fall off, twigs wither, and flower ears dry up; Eventually the whole plant withered and died. In the underground part of the diseased plant, first, the small roots change color and rot, or the stem base near the surface changes color slightly, and the vascular bundles begin to brown; Then the lateral roots turned black and necrotic; The stem base and taproot of severely diseased plants rot and die, and pink mold grows at the stem base when it is wet.

The difference between pepper blight and pepper blast is that although some pepper blast plants also have yellow leaves and wilting symptoms, the whole plant dies quickly. However, the blight of pepper generally lasts from half a year to several years from the yellowing of some leaves to the death of the whole plant. Some Fusarium wilt plants show that half of the aboveground parts are dead and the other half are still alive, showing symptoms of slow decline. Pepper blight plants mostly occur on the main vines 20 cm above and below the ground. The roots near the infected underground main vines were infected, turned black and rotted, and gradually spread to the roots. At this time, the next root has not been hurt. The first infection point of pepper Fusarium wilt is small roots, and then it gradually spreads upward.

The pathogenic bacteria are fungi, and their scientific names are Fusarium putrefaction and Fusarium oxysporum. It is reported that the Fusarium wilt of pepper caused by mixed infection of Fusarium and nematodes is more serious.

Epidemic situation

Both climate and soil factors will affect the occurrence of diseases. High temperature, dry, humid and humid climate is conducive to the infection and spread of this disease. Soil PH below 6, sandy soil or sandy loam, low fertility, poor drainage, loose soil structure, poor permeability of subsoil and fields with a large number of nematodes are all conducive to the occurrence of this disease.

Prevention and cure method

1, pay attention to the selection of planting sites, do a good job in the irrigation and drainage system of pepper orchard to prevent soil waterlogging and soil drought.

2. Choose disease-free healthy seedlings for planting.

3. Rational fertilization, sufficient base fertilizer, increased application of organic fertilizer, and no partial application of chemical fertilizer. When planting, the base fertilizer, especially the burnt soil, is not

Contact with the root system; Use decomposed organic fertilizer when topdressing to avoid fertilizer damage.

4. Insecticides should be applied in pepper orchards with a large number of nematodes to reduce the harm of nematodes to roots and the occurrence of Fusarium wilt.

5. Spray the newly infected Fusarium oxysporum strain with the solution of 1∶250 times, once every 7- 10 days, for three times. Or take 40% carbendazim and thiram 1: 1: 500 times.

I. Diseases

According to foreign reports, there are nearly 50 kinds of pathogens involved in the harm of pepper at all stages of its growth and development, including fungi, bacteria, viruses, nematodes and algae. According to 1992 investigation results of tropical crop diseases and insect pests in five southern provinces of China, there are 3/kloc-0 species of pepper diseases in China, among which the main diseases are pepper gangrene, pepper bacterial leaf spot, pepper mosaic, pepper Fusarium wilt and pepper root-knot nematode, and the secondary diseases are charcoal blast, root rot (red root rot, brown root rot and purple root rot) and fungus.

(1) Phytophthora capsici

Pepper blight, also known as pepper-based rot, rapid decline disease and black water disease, is the most important pepper disease in pepper planting areas in the world. It was first discovered in Sandraman, India in 1926, and later occurred in Indonesia, Malaysia, Cambodia and some countries in South America and Africa. There have been many pandemics in Sarawak, Malaysia, which led to a large-scale reduction of pepper production and forced the serious pepper orchard to be abandoned. 1960 The first large-scale epidemic of pepper blast in Hainan Province of China destroyed a large area of pepper orchards. The pepper area didn't recover until 1969, but it was damaged by pepper blast again in 1970 ~ 1972, and 78% of pepper orchards were destroyed by this disease, which caused serious losses to pepper production in China. The disease also occurred in pepper growing areas in Guangdong, Yunnan and Guangxi.

symptom

The root system, base of main vine, branches and vines, leaves, flowers and fruits of pepper plants are all damaged. The base of the main vine (called pepper head) causes the most damage, which often causes the whole pepper plant to wilt and die. At the base of the main vine, 20cm above and below the ground, it was destroyed by a cork, and there were no obvious symptoms at the initial stage of infection. After scraping off the outer skin, the inner cortex turns black and the xylem is light brown. The longitudinal section of the main vine shows that xylem vessels turn black, brown stripes spread up and down, and the junction between disease and health is not obvious. In the later stage, the outer epidermis turns black, decays and falls off, black liquid flows out from the decayed xylem (hence the name blackwater disease), and the stele splits into a bundle of loose vessel fibers. When the diseased plant is dug up, it can be seen that the root system near the infected underground main vine is infected, turns black and decays, and gradually spreads to the root tip, while other roots in the lower layer are not damaged, which is obviously different from the symptoms of pepper flooding and fertilizer damage, starting from the root tip and then rotting the big root. The base of the main vine is infected with rotten plants, and the whole leaf canopy becomes dim, the leaves are dim, dehydrated, and the leaves wither and fall off. If the weather is dry and hot, the diseased plant can wither suddenly in a few days, and finally, as the tender vines turn black, the dead tender vines can fall off one by one.

The leaves on the lower branches of the plant were the first to get sick, and began to show light brown or gray-black stains, and the spots quickly expanded into dark brown round lesions, and the edges spread radially and the outline was not obvious. When the environment is wet, white mold grows on the back of the diseased leaves, that is, hyphae and sporangia of the pathogen. When the climate is dry, the mildew disappears, the diseased spots turn grayish brown, and the diseased leaves finally fall off. The diseased cortex of shoots and vines produces dark green scars soaked in water, and when it is serious, it falls off from a part. Inflorescence and ear diseases generally start from the top, resulting in waterlogging spots, and then turn black and dry.

cause of a disease

The pathogens are fungi, which are named Phytophthora capsici and Phytophthora parasitica. It belongs to the phycomycetes and belongs to the genus Peronospora. The incidence of these two Phytophthora species in pepper producing areas in China is roughly the same, and they are both the main pathogens of pepper blight.

Infection cycle

Both Phytophthora pathogens can survive in diseased tissues and soil of pepper plants. Soil containing bacteria, diseased tissues of diseased (dead) plants and other host plants can provide primary infection sources. Germs are mainly transmitted through running water (running water, irrigation water) and wind and rain. People, livestock, farm tools, seedlings and snails can also carry germs to spread diseases. The germ tube of sporangium or zoospore can invade from the natural orifice or wound of the host, or directly penetrate the tender tissue to inoculate the main vine of cork pepper. Incubation period 15 ~ 20 days, inoculated with tender leaves or vines. The incubation period is 2 ~ 5 days.

Epidemic law

The prevalence of pepper blast is closely related to soil types, topography, cultivation measures and rainfall in pepper orchards. Generally, the soil is sticky, the drainage is not smooth, or the low-lying water accumulates early, and the disease is serious; On the contrary, sandy soil and well-drained diseases are lighter. Pepper orchards are relatively concentrated, there is no shelter forest, or pepper heads are sprained when changing columns and tying vines, or weeds are weeded in diseased orchards in rainy days, or pepper orchards are prone to epidemic situations in rainy years, especially in years with many typhoons. 1 year, the occurrence and epidemic of the disease can be roughly divided into three stages: the central disease plant (area) stage, the general transmission stage, the serious illness and mass death stage and the decline of epidemic speed stage. The disease begins to occur on a few plants from March to April every year, and the epidemic period of plague is from August to165438+1October.

Prevention and cure method

In order to control the epidemic of pepper blight, comprehensive disease prevention measures combining agricultural measures with chemical control must be taken.

1, agricultural preventive measures

(1) Site selection for the new Zanthoxylum bungeanum Garden requires land planning and farmland capital construction. That is, choose land with good water permeability and easy drainage to grow peppers; Pepper orchards should not be too concentrated, and the area of each pepper orchard should be 3 ~ 5 mu, and shelterbelts should be planted around it; Terraces or contour ridges should be built in the park, and circular drainage ditches and small drainage ditches between rows should be dug to prevent germs from spreading through running water; Build mounds in lowlands and grow peppers.

(2) Using pruned vines of disease-free seedlings in disease-free orchards as cutting materials to raise seedlings in disease-free plots.

(3) Strengthen tending management, weeding and fertilization should be carried out in sunny days, and be careful not to hurt the pepper heads and roots; Prune branches and vines close to the ground properly to reduce the humidity of pepper heads and reduce the diseases of lower leaves; Cultivate the soil in time to make the pepper head higher than the ground to prevent stagnant water and bacteria from invading the pepper head with running water; Remove dead leaves and dead pepper heads in the garden in time; Non-biased application of nitrogen fertilizer; Plant mulch plants between rows of pepper orchards, or use hay as a dead cover to reduce the spread of bacteria in running water and splash when it rains.

(4) Grasp the condition in time, do a good job in isolating the epidemic season of the disease in the ward, especially during the typhoon and rain period, assign special personnel to check the situation of each garden, and once the diseased plants are found, apply pesticides in time to prevent and control them, and block and isolate the ward, and prohibit people and animals from entering. Don't take the farm tools used in the ward to the disease-free park. In field management, there should be no disease garden first, and then the disease garden. In rainy days and when the soil is wet, stop agricultural activities such as weeding and fertilization in the sick park to reduce human transmission.

2. Chemical control

At the early stage of the disease, 1% bordeaux solution or 40% phosphoethyl aluminum wettable powder 100 times solution was sprayed on the central area (plant) and surrounding plants, and 1% copper sulfate solution or 1% bordeaux solution was sprayed on the soil between the lines of the disease area. Dig up dead plants in time and transport them out of the garden for burning. Dig out the diseased soil and expose it to the sun or disinfect it with 1% copper sulfate solution.

(2) Bacterial leaf spot of pepper

Bacterial leaf spot of pepper is one of the important diseases in pepper producing areas. 1962 in some pepper orchards in Hainan province, China.

It started to occur sporadically. After 1966, the disease became more and more common and serious. In the early 1970s, it was widely popular in Wanning County, Hainan Province. The leaves of seriously ill plants fall off, the branches and vines dry up and lose production capacity until the whole plant dies. The rate of diseased plants in 36 pepper orchards in a seriously ill farm was 73.8%, the rate of dead plants was 35.5%, and the yield was reduced by 50%, which caused serious economic losses to pepper production.

symptom

This disease occurs in pepper orchards of all ages. Large and medium-sized peppers are common, and leaves, branches, vines, inflorescences and fruit ears all have effects, mainly affecting mature leaves. Water stains appear in the early stage of leaf infection, and turn into purple-brown, round or polygonal spots after a few days. Lesions are enlarged, or multiple lesions converge to form 1 large gray-white lesions. There are 1 purple-brown dividing lines at the junction of disease and health, with yellow halo at the edge. Under wet conditions, bacterial exudation appeared on the diseased spots on the back of the leaves, which became a gelatinous film after drying. When branches and vines are injured, germs invade from internodes or wounds, showing irregular purple spots. When the diseased branch is cut, the catheter changes color. When the ear is infected, a purple-brown round lesion appears at first, and then the whole ear turns black. When seriously ill, leaves, branches, flowers and fruits are easy to fall off, but only bare main vines are left, and eventually the main vines will dry up and die. This pathogen not only harms pepper, but also infects piperaceae plants such as betel leaves, pods and pods.

cause of a disease

The pathogen is a kind of bacteria, the scientific name is Xanthomonas campestris. The thallus is short rod-shaped, with blunt end, and the size is 0.4 ~ 0.7 um× 1.0 ~ 2.4 um, which is arranged singly or in pairs, and 3 ~ 5 of them are arranged in short chains, and Gram staining is negative. Without spores and capsules, a single flagella is extremely healthy. After being cultured on beef paste peptone agar medium for 7 days, the colony is round with a diameter of 65438±0 ~ 2mm, with smooth surface, shiny edge, cheese-like, slightly convex, translucent or opaque, with milky white bands and no fluorescent pigment.

In addition to pepper, this fungus can also infect leaves, fake clams and Hainan clams.

Infection cycle

This disease exists in pepper orchards all year round. Dry bacteria on diseased tissues overflow and dissolve in water, and spread through wind and rain or water droplets sputtering. Insects and people can also spread diseases. Bacteria invade through wounds or natural openings. The incubation period is 10 ~ 14 days.

Epidemic law

1 year in dry season, there is little rain and low relative humidity, and there are only sporadic diseased leaves in the field; At the beginning of the rainy season, the rain increased, the relative humidity was high, the dew was heavy, and a large number of new spots appeared. The lesion expanded rapidly. Generally, the peak of 1 will appear around 1 month after heavy rainfall. If there is a short-term drought, the number of newly infected leaves will be significantly reduced, and the disease condition will decline, indicating that there are multiple peaks in 1 year. Rainfall and high temperature are the main conditions for the occurrence and epidemic of the disease, especially the large amount of damage caused by typhoon and rain to pepper plants is conducive to the spread and invasion of pathogenic bacteria. If there is continuous rain after the wind, the disease will accumulate and spread.

Pepper orchards with heavy soil, poor drainage, dense row spacing and high air humidity are prone to diseases. In the pepper orchard without shelter forest, the plants on the windward side are seriously ill.

Prevention and cure method

1. Do a good job in the planning and capital construction of pepper garden. Don't over-concentrate the pepper garden, covering an area of 3 ~ 5 mu, plant shelter forests around it, and dig drainage ditches inside and outside the pepper garden.

2. Planting disease-free seedlings It is forbidden to introduce seedlings from the ward and cultivate disease-free pepper seedlings.

3. Regularly check the condition and eliminate the central disease strain in time. Before the rainy season comes, all the diseased leaves infected with bacterial leaf spot in the garden should be removed and burned centrally. After the rain, check the diseased plants in time and remove the diseased leaves in time. The diseased plants and their neighboring plants should be sprayed with 1% bordeaux solution or 40% phosphoethyl aluminum (ethyl ester) wettable powder 100 times, and the diseased plants should be continuously sprayed on the ground for disinfection. If there are too many diseased leaves in seriously ill plants and it is difficult to remove them manually, we can spray 1% copper sulfate solution to make the leaves fall off as a whole, then add more fertilizer, shade properly and resume growth. For some seriously ill plants with serious defoliation and bare top branches and vines, all the upper branches and vines can be pulled out, leaving 1/2 plants, then topdressing and strengthening management. During the epidemic period, Bordeaux solution or ethyl phosphate solution can be sprayed on the diseased pepper orchard regularly, 10 ~ 14 days, 1 time, and sprayed several times.

(3) Pepper mosaic disease

Pepper mosaic disease, also known as pepper virus disease, is one of the important diseases of pepper. The disease is common in pepper orchards in Hainan, Guangdong, Guangxi, Yunnan, Fujian and other provinces (regions) in China. Infected plants are short in plant type and weak in growth potential, and their growth is only 1/2 ~ 1/3 of normal plants. The rate of diseased plants in seriously ill gardens is as high as 80% ~ 90%, resulting in the loss of dried pepper yield of 27 ~ 43%.

symptom

This disease usually shows two symptoms. One is that the plant is short, the internodes of the main vines are shortened, the leaves are mottled and mosaic, the leaves shrink, become thicker, smaller, narrower, deformed and curled, the ear of fruit is short, the fruit grains are small and few, and the yield is low; The other is that the plant height and leaf size accept normal plants, but the tender leaves at the top become smaller or the leaf color is uneven, which shows common mosaic symptoms.

cause of a disease

The pathogen is a virus, the scientific name is cucumber mosaic virus. The plasmid of the virus is spherical, with a diameter of 27 ~ 30 mm The host range of cucumber mosaic virus is very wide, including some dicotyledonous plants and monocotyledonous plants such as flowers, garden trees and weeds. It is known that cucumber mosaic virus that infects pepper can also infect false fruits, dead leaves and false Physalis.

Infection cycle

The disease mainly spread to the newly planted pepper garden through the poisonous scissors (seedlings). It can also be spread in pepper fields through grafting and aphids. Aphid gossypii and Aphid Spiraea are two main vectors of pepper mosaic disease. It is reported that Aphis gossypii and Aphis embroidered cannot directly transmit the virus to pepper plants to make them sick, but can only transmit the disease through the intermediate host Physalis alkekengi. It has been proved that mechanical juice harvesting does not spread diseases.

Occurrence law

Because pepper production mainly depends on asexual cutting as seedlings, the seedlings propagated by cutting off diseased vines are planted early and seriously. The epidemic intensity of mosaic disease in pepper orchard is closely related to the number of infected seedlings. In addition, the occurrence of mosaic disease is closely related to climatic conditions, especially during high temperature and drought, the growth of plants and the appearance of new buds are slow, coupled with the large number of aphids in high temperature and drought, which is conducive to the spread and spread of the disease.

Prevention and cure method

1. Strengthen quarantine at the place of origin to prevent seedlings bred in epidemic areas from being introduced into new pepper planting areas. Even in diseased areas, branches and vines should not be cut from diseased plants to propagate seedlings.

2. Pay attention to tending management. Apply sufficient base fertilizer before planting pepper and topdressing regularly after planting. In the new plantation, it is necessary to check frequently and insert the shade in time until the branches and vines of the seedlings can cover the pepper heads (about after the second pruning), so that the shade can be removed. Pruning, especially the first pruning after planting, should be carried out on cloudy days in rainy season to facilitate the rapid extraction and vigorous growth of new branches; Avoid pruning vines in hot and dry weather.

3. After planting, clear the diseased plants at the young age of 1 ~ 2. If you find a diseased plant with mosaic symptoms or shortening, you should dig it out and burn it, and then replant it in time. If mature pepper plants have branches with obvious mosaic symptoms, the diseased branches should be cut off and treated with water and fertilizer to promote the emergence of new shoots.

4. Prevention and treatment of aphids In the dry season and the period when there are many tender buds, which are conducive to the occurrence and spread of aphids, 40% dimethoate EC 1000 times solution can be sprayed in the aphid occurrence season to eradicate the aphids that spread the virus and control the spread of mosaic disease.

(4) Fusarium wilt of pepper

Pepper Fusarium wilt, also known as chronic wilt, chronic decline disease and yellowing disease, is an important disease second only to pepper blast. In the late 1920s and early 1930s, a serious chlorosis occurred in Bangka Island, Indonesia, and 22 million peppers were lost, with a loss rate as high as 90%. India lost 10% of pepper plants due to Fusarium wilt, while Guina lost 30%, which also caused serious losses in Malaysia and Brunei. In Brazil, Fusarium oxysporum caused by rot is more serious than pepper blast, which is the biggest disease in Brazilian pepper production. In recent ten years, some pepper orchards in Wenchang, Qionghai, Wanning, Danzhou, Qiongzhong, Baisha and Ledong in Hainan Province and Zhanjiang in Guangdong Province have also suffered from pepper wilt, most of which occurred in fruit-bearing pepper orchards, and its distribution area was more extensive than pepper blast, and the loss of pepper plants caused by it was generally 5% ~ 15%, and there was an increasing trend year by year.

symptom

The common manifestations of infected plants are that the leaves fade and turn yellow, the growth is not prosperous and the plants are shortened. In severe cases, the whole plant withered and declined. The aboveground part of the diseased plant, at first, some leaves lose luster and gradually turn yellow, and then most leaves turn yellow; Some yellow leaves wilt, droop, fall off, twigs wither, and flower ears dry up; Eventually the whole plant withered and died. In the underground part of the diseased plant, first, the small roots change color and rot, or the stem base near the surface changes color slightly, and the vascular bundles begin to brown; Then the lateral roots turned black and necrotic; The stem base and taproot of severely diseased plants rot and die, and pink mold grows at the stem base when it is wet.

The difference between pepper blight and pepper blast is that although some pepper blast plants also have yellow leaves and wilting symptoms, the whole plant dies quickly. However, the blight of pepper generally lasts from half a year to several years from the yellowing of some leaves to the death of the whole plant. Some Fusarium wilt plants show that half of the aboveground parts are dead and the other half are still alive, showing symptoms of slow decline. Pepper blight plants mostly occur on the main vines 20 cm above and below the ground. The roots near the infected underground main vines were infected, turned black and rotted, and gradually spread to the roots. At this time, the next root has not been hurt. The first infection point of pepper Fusarium wilt is small roots, and then it gradually spreads upward.

The pathogenic bacteria are fungi, and their scientific names are Fusarium putrefaction and Fusarium oxysporum. It is reported that the Fusarium wilt of pepper caused by mixed infection of Fusarium and nematodes is more serious.

Epidemic situation

Both climate and soil factors will affect the occurrence of diseases. High temperature, dry, humid and humid climate is conducive to the infection and spread of this disease. Soil PH below 6, sandy soil or sandy loam, low fertility, poor drainage, loose soil structure, poor permeability of subsoil and fields with a large number of nematodes are all conducive to the occurrence of this disease.

Prevention and cure method

1, pay attention to the selection of planting sites, do a good job in the irrigation and drainage system of pepper orchard to prevent soil waterlogging and soil drought.

2. Choose disease-free healthy seedlings for planting.

3. Rational fertilization, sufficient base fertilizer, increased application of organic fertilizer, and no partial application of chemical fertilizer. When planting, the base fertilizer, especially the burnt soil, is not

Contact with the root system; Use decomposed organic fertilizer when topdressing to avoid fertilizer damage.

4. Insecticides should be applied in pepper orchards with a large number of nematodes to reduce the harm of nematodes to roots and the occurrence of Fusarium wilt.

5. Spray the newly infected Fusarium oxysporum strain with the solution of 1∶250 times, once every 7- 10 days, for three times. Or take 40% carbendazim and thiram 1: 1: 500 times.

(5) pepper root-knot nematode disease

Pepper root-knot nematode disease is widely distributed, which is one of the important diseases in pepper producing areas in the world. Hainan, Guangdong, Guangxi,

The disease occurred in all pepper growing areas in Yunnan and Fujian. The roots of the affected plants were destroyed and the growth of the above-ground parts was stagnant.

Internodes become shorter, leaves become dull, turn yellow, wither, drop flowers and fruits, and even the whole plant dies, especially young peppers.

symptom

Both big roots and small roots of pepper can be parasitized by root-knot nematodes. Root-knot nematodes invade the roots, mostly from the root tip, forming irregular nodules of different sizes, mostly spherical. If the growth point of the young root is not invaded and continues to grow, it will be invaded again to produce nodules, which often make the nodules on the injured root string. The initial nodules are milky white, then turn light brown or dark brown, and finally turn dark brown. Root nodules are cracked in dry season and rotted in rainy season.

cause of a disease

The pathogens of pepper root-knot nematodes are root-knot nematodes in southern China and Java. This kind of nematode is dioecious, overlapping generations and harmful all year round.

Female insect: pear-shaped, with a prominent "neck" and a spherical "trunk". The body length is 0.8 ~ 1.0 mm, the diameter is about 0.6 mm, and it lives in the nodule.

Male worm: slender, eel-shaped, the standard form of nematode. Body length 1.0 ~ 1.5 mm, temporarily living in soil.

Larvae: The first larva is temporarily in the oocyst when it hatches, and soon comes out from the end of the oocyst. They are eel-shaped, colorless and transparent, active, temporarily free to live, and can invade the root of the host. The second stage larvae are formed by the first stage larvae invading the root tissue of the host and immediately falling off. In the second stage, the sex organs of the larvae gradually develop, and the "trunk" gradually expands to form pear-shaped female adults, while other male larvae become eel-shaped male adults.

Eggs: Oval or ovoid, with a long diameter of 0.09 mm and a short diameter of 0.04 mm, colorless and transparent, arranged neatly in the oocysts, and most of them are arranged vertically.

Occurrence and prevalence of root-knot nematodiasis.

Root-knot nematodes are widely distributed and have many host plants. It is reported that there are more than 700 host plants of root-knot nematodes/kloc-0. In Hainan Island, besides peppers, bananas, pineapples, papaya, guava, sugarcane, tea trees, coffee, cocoa, citronella, watermelon, peppers, eggplant, loofah and bitter gourd are also harmed. Therefore, pepper root-knot nematode disease is easy to occur when planted on the land where root-knot nematode host plants have been planted. The first stage larvae of root-knot nematodes can be found in Hainan soil all year round, so the infection of host plants also occurs all year round. The first stage larvae are mostly concentrated in the host root system and the soil around the root system. The occurrence and prevalence of root-knot nematodiasis are related to soil types, climate and cultivation management. Generally, it is more serious in sandy soil with courage, poor cultivation management and lack of fertilizer, especially organic fertilizer. Pepper orchards with dry soil are also prone to occur, and the symptoms are more obvious and serious in dry season.

Prevention and cure method

1, pay attention to the position. Avoid cultivating pepper seedlings or planting peppers in areas infected by previous crops (hosts). Select disease-free seedlings.

2. Dig deep into the soil. In the reclaimed pepper orchard, the soil is deeply ploughed for more than 40 cm in dry season, and it is repeatedly ploughed for 2 ~ 3 times. Near the water source, you can also flood the field for more than two months, drain the water and plant peppers.

3. Strengthen tending management. Cover with thick plastic film, apply more decomposed organic fertilizer, apply deep hole fertilization, and introduce pepper roots into the soil layer below 40 cm. If pepper can be well managed at seedling stage and young stage, with developed root system and vigorous growth, the resistance of plants to nematodes can be enhanced. As long as the juvenile stage is passed, mature plants can still grow and bear fruit normally even if they are invaded by root-knot nematodes. Phosphorus and potassium fertilizer should be applied properly in the process of pipe caressing.

4. Chemical control. By applying appropriate nematicides or soil fumigants, such as dibromochloropropane to fumigate the soil, or treating the soil with dichlorvos, dichlorvos, aldicarb, carbofuran and Mi Le, a certain control effect can be achieved. Recently, a newly developed nematicide "Shaxianling" has a good control effect on pepper and banana root-knot nematodes, and can also be used to control pepper root-knot nematodes.