Pests and diseases of papaya and their control
2022-08-28 10:08:04
1 Papaya main diseases There are many kinds of papaya diseases known. Among them, the most common and serious hazard is papaya ring mosaic disease caused by virus. In addition, there are anthracnose, leaf spot and storage diseases.
1.1 Papaya ring mosaic disease Papaya ring mosaic disease is generally called mosaic disease, which occurs in the main planting areas of papaya. Symptoms: In the early stage of the disease, water spots appear on the stems, veins and veins of the young leaves, followed by yellow-green phase or dark green and light green mosaic disease on the young leaves; also appear on the epidermis of susceptible fruits. Water-stained round spots (ring spots), several round spots can be combined into an irregular shape. During the low temperature period, most of the leaves of the diseased plants fell off, and the young leaves appeared deformed. Papaya virus disease is mainly caused by papaya mosaic virus, papaya ring spot virus and papaya leaf malware. The natural media are peach aphid and cotton aphid, and the transmission rate is very high. The friction is very easy to transmit, and the leaves of the diseased plants in the field can be in contact with the leaves of the healthy plants to be infected.
Incidence conditions: 1 climatic conditions. Warm and dry years, serious. Therefore, under the climatic conditions of the Guangzhou area, there may be two incidence peaks and a green back strain period of one year. 4 to 5 and October to early November, the monthly average temperature is 20 ~ 25 ℃, most strains of incidence at this time, the most obvious symptoms; 7-8 months, the average temperature is 27 ~ 28 ℃, a green back strain of , the symptoms disappear or slow down. The disease has a high temperature of inhibition of virus, strain heating each day to 40 ℃, heated 4 hours, 4 days, green back strain significantly, the lesion may disappear, but a few days after the cessation of high temperature, symptoms again. 2 Orchard location. Because this disease is mainly transmitted by the aphid, where the old orchard adjoining or adjacent orchard diseased plants fast onset, high incidence. The orchards planted in successive years have an early onset and a high incidence. 3 plant growth period and growth status. Papaya can be susceptible to the whole growth and development stage.
Control methods: There is no cure method at present, but comprehensive prevention measures based on cultivation measures are adopted. 1 Selection of disease-resistant varieties. 2 Strengthen cultivation management, improve cultivation management measures, and enhance plant resistance to disease. 3 timely excavation of diseased plants. 4 Eliminate the source of the disease and properly isolate it. 5 medicinal cockroaches Spray at the peak of the locust migration, especially during the dry season. On the weeds that the locusts around the orchard like to inhabit, be careful to remove them at the same time.
1.2 Papaya anthracnose This disease is another important disease after papaya ring mosaic disease, which is common in Guangdong, Guangxi, Fujian and Taiwan. The disease can occur throughout the year, with the most serious in autumn, and the incidence of young fruit and mature fruit is more, which can continue to be harmful during fruit storage. The disease is mainly harmful to the fruit, followed by damage to the leaves, petioles and stems. The damaged fruit surface first appeared yellow or dark brown water-stained small spots. As the lesions gradually expanded, the lesions were recessed in the middle, and concentric circles appeared, and the upper vermilion clay was added, and then the black spots became smaller. On the leaves, the lesions mostly occur at the tip and leaf margin, brown, irregular, with small black spots on the spots. Pathogen is anthrax bacteria, the bacteria overwinter in plant debris. Under high temperature and humidity conditions, it is conducive to the epidemic of diseases. Conidia are transmitted by wind and rain and insects, and are invaded by stomata, wounds or directly from the epidermis.
Control method: 1 winter clearing garden. Thoroughly remove the diseased body, burn it intensively or deeply, and spray the Bordeaux mixture once. 2 chemical control. In the period from August to September, the spraying season is sprayed every 10 to 15 days, and even sprayed 3 to 4 times. The medicine can be selected from 70% methyl thiophanate WP 800-1000 times solution, 40% virulence suspension 250-350 times liquid or 50% carbendazim WP 800 times liquid spray, and timely remove the disease fruit. . 3 timely picking fruit, avoid over-harvesting and crushing the fruit when picking, spray 70% methyl thiophanate-methyl WP 1000 times in the two weeks before fruit picking, can play a role in preservation and preservation.
1.3 Papaya tumor disease After the onset, the leaves become smaller, the petiole shortens, the tip of the young leaves becomes brown and dead, the leaves can curl and fall off, the female flowers can change male flowers, and the flowers often die. When the fruit is very small, it falls off a lot. There is milk flowing out on the fruit, young leaves, flowers and stems, and there are white dry knots at the outflow site. The fruit has symptoms of milk effluent in the young fruit stage and even in the early stage of maturity, and most of it flows out on the sunny side of the fruit. After the fruit juice flows out of the juice, it will slowly fester and soften, and the ulceration will turn brown, and the fruit without ulceration will have a tumor. Protrusion, uneven. The severe diseased fruit is degraded and the young white seeds turn brown. This is a physiological disease caused mainly by boron deficiency in the soil.
Control method: timely supplement boron. Boron or boron can be applied to the soil. Boric acid or borax is used. A small hole is dug next to the plant. 2 to 5 g of borax or 3 g of boric acid is applied to each hole, usually 1 to 2 times. The external application of boron can spray 0.2% boric acid, spray once every 1 week, and spray 3 to 5 times. Application of borax or boric acid should be done when the papaya plant is budded.
2 Papaya main pests Common pests that harm papaya are papaya round scale insects, red spiders, aphids, snails, etc., and seedlings are often damaged by underground pests such as small tigers and giant salamanders.
2.1 Red spiders Take the sputum and the scorpion on the back of the leaves to absorb the juice. The green leaves of the damaged leaves are yellow spots, and the yellow spots are plaque-like when the leaves are seriously damaged, which is like the symptoms of mosaic disease. The lack of green in the damaged leaves affects photosynthesis, and when the leaves are severe, the leaves are shed and the plant growth is affected. In the Guangdong region, papaya is harmful to red spiders all year round. It occurs more than 20 generations a year, overlapping generations, but peaks occur in April-May and August-November.
Control methods: 1 agricultural control. When the papaya is cut, it is necessary to remove the field debris and weeds in time. 2 biological control. It is found that the red spider can spray water 3 to 4 times, reduce insects and protect natural enemies from eating red spiders. 3 The peak period of drug control. When using the medicine, the variety, application method and frequency of the pesticide should be considered to protect the natural enemy as much as possible. The colloidal sulfur suspending agent 250 times solution can be sprayed once every 5 to 7 days during the hatching period of the larva, and even sprayed 2 to 3 times. Acaricide 73% gram of emulsifiable concentrate 1500-2000 times solution, 5% Nisolron emulsifiable concentrate 2000 times solution or 50% Tolk WP 2,000 to 2500 times solution can also be used.
2.2 Aphids Aphids are one of the main vector insects of papaya ring mosaic disease, mainly including peach aphid and cotton aphid. Control methods: 1 Seedlings should be kept away from the peach plant and remove the weeds in the field. 2 cut off the diseased plants of the mites. 3 畦 face covered with silver-gray film drive. In the seedling stage and the pre-growth stage, the gauze (32 mesh) net room is used for flood control. 4 found aphids and the peak application of chemical control. 50% Bataan soluble powder 1000 times solution, 40% dimethoate 1000 times solution, 50% anti-Pu Wei WP 2000-3000 times solution or 50% malathion EC 1500-2000 times solution can be used alternately.
1.1 Papaya ring mosaic disease Papaya ring mosaic disease is generally called mosaic disease, which occurs in the main planting areas of papaya. Symptoms: In the early stage of the disease, water spots appear on the stems, veins and veins of the young leaves, followed by yellow-green phase or dark green and light green mosaic disease on the young leaves; also appear on the epidermis of susceptible fruits. Water-stained round spots (ring spots), several round spots can be combined into an irregular shape. During the low temperature period, most of the leaves of the diseased plants fell off, and the young leaves appeared deformed. Papaya virus disease is mainly caused by papaya mosaic virus, papaya ring spot virus and papaya leaf malware. The natural media are peach aphid and cotton aphid, and the transmission rate is very high. The friction is very easy to transmit, and the leaves of the diseased plants in the field can be in contact with the leaves of the healthy plants to be infected.
Incidence conditions: 1 climatic conditions. Warm and dry years, serious. Therefore, under the climatic conditions of the Guangzhou area, there may be two incidence peaks and a green back strain period of one year. 4 to 5 and October to early November, the monthly average temperature is 20 ~ 25 ℃, most strains of incidence at this time, the most obvious symptoms; 7-8 months, the average temperature is 27 ~ 28 ℃, a green back strain of , the symptoms disappear or slow down. The disease has a high temperature of inhibition of virus, strain heating each day to 40 ℃, heated 4 hours, 4 days, green back strain significantly, the lesion may disappear, but a few days after the cessation of high temperature, symptoms again. 2 Orchard location. Because this disease is mainly transmitted by the aphid, where the old orchard adjoining or adjacent orchard diseased plants fast onset, high incidence. The orchards planted in successive years have an early onset and a high incidence. 3 plant growth period and growth status. Papaya can be susceptible to the whole growth and development stage.
Control methods: There is no cure method at present, but comprehensive prevention measures based on cultivation measures are adopted. 1 Selection of disease-resistant varieties. 2 Strengthen cultivation management, improve cultivation management measures, and enhance plant resistance to disease. 3 timely excavation of diseased plants. 4 Eliminate the source of the disease and properly isolate it. 5 medicinal cockroaches Spray at the peak of the locust migration, especially during the dry season. On the weeds that the locusts around the orchard like to inhabit, be careful to remove them at the same time.
1.2 Papaya anthracnose This disease is another important disease after papaya ring mosaic disease, which is common in Guangdong, Guangxi, Fujian and Taiwan. The disease can occur throughout the year, with the most serious in autumn, and the incidence of young fruit and mature fruit is more, which can continue to be harmful during fruit storage. The disease is mainly harmful to the fruit, followed by damage to the leaves, petioles and stems. The damaged fruit surface first appeared yellow or dark brown water-stained small spots. As the lesions gradually expanded, the lesions were recessed in the middle, and concentric circles appeared, and the upper vermilion clay was added, and then the black spots became smaller. On the leaves, the lesions mostly occur at the tip and leaf margin, brown, irregular, with small black spots on the spots. Pathogen is anthrax bacteria, the bacteria overwinter in plant debris. Under high temperature and humidity conditions, it is conducive to the epidemic of diseases. Conidia are transmitted by wind and rain and insects, and are invaded by stomata, wounds or directly from the epidermis.
Control method: 1 winter clearing garden. Thoroughly remove the diseased body, burn it intensively or deeply, and spray the Bordeaux mixture once. 2 chemical control. In the period from August to September, the spraying season is sprayed every 10 to 15 days, and even sprayed 3 to 4 times. The medicine can be selected from 70% methyl thiophanate WP 800-1000 times solution, 40% virulence suspension 250-350 times liquid or 50% carbendazim WP 800 times liquid spray, and timely remove the disease fruit. . 3 timely picking fruit, avoid over-harvesting and crushing the fruit when picking, spray 70% methyl thiophanate-methyl WP 1000 times in the two weeks before fruit picking, can play a role in preservation and preservation.
1.3 Papaya tumor disease After the onset, the leaves become smaller, the petiole shortens, the tip of the young leaves becomes brown and dead, the leaves can curl and fall off, the female flowers can change male flowers, and the flowers often die. When the fruit is very small, it falls off a lot. There is milk flowing out on the fruit, young leaves, flowers and stems, and there are white dry knots at the outflow site. The fruit has symptoms of milk effluent in the young fruit stage and even in the early stage of maturity, and most of it flows out on the sunny side of the fruit. After the fruit juice flows out of the juice, it will slowly fester and soften, and the ulceration will turn brown, and the fruit without ulceration will have a tumor. Protrusion, uneven. The severe diseased fruit is degraded and the young white seeds turn brown. This is a physiological disease caused mainly by boron deficiency in the soil.
Control method: timely supplement boron. Boron or boron can be applied to the soil. Boric acid or borax is used. A small hole is dug next to the plant. 2 to 5 g of borax or 3 g of boric acid is applied to each hole, usually 1 to 2 times. The external application of boron can spray 0.2% boric acid, spray once every 1 week, and spray 3 to 5 times. Application of borax or boric acid should be done when the papaya plant is budded.
2 Papaya main pests Common pests that harm papaya are papaya round scale insects, red spiders, aphids, snails, etc., and seedlings are often damaged by underground pests such as small tigers and giant salamanders.
2.1 Red spiders Take the sputum and the scorpion on the back of the leaves to absorb the juice. The green leaves of the damaged leaves are yellow spots, and the yellow spots are plaque-like when the leaves are seriously damaged, which is like the symptoms of mosaic disease. The lack of green in the damaged leaves affects photosynthesis, and when the leaves are severe, the leaves are shed and the plant growth is affected. In the Guangdong region, papaya is harmful to red spiders all year round. It occurs more than 20 generations a year, overlapping generations, but peaks occur in April-May and August-November.
Control methods: 1 agricultural control. When the papaya is cut, it is necessary to remove the field debris and weeds in time. 2 biological control. It is found that the red spider can spray water 3 to 4 times, reduce insects and protect natural enemies from eating red spiders. 3 The peak period of drug control. When using the medicine, the variety, application method and frequency of the pesticide should be considered to protect the natural enemy as much as possible. The colloidal sulfur suspending agent 250 times solution can be sprayed once every 5 to 7 days during the hatching period of the larva, and even sprayed 2 to 3 times. Acaricide 73% gram of emulsifiable concentrate 1500-2000 times solution, 5% Nisolron emulsifiable concentrate 2000 times solution or 50% Tolk WP 2,000 to 2500 times solution can also be used.
2.2 Aphids Aphids are one of the main vector insects of papaya ring mosaic disease, mainly including peach aphid and cotton aphid. Control methods: 1 Seedlings should be kept away from the peach plant and remove the weeds in the field. 2 cut off the diseased plants of the mites. 3 畦 face covered with silver-gray film drive. In the seedling stage and the pre-growth stage, the gauze (32 mesh) net room is used for flood control. 4 found aphids and the peak application of chemical control. 50% Bataan soluble powder 1000 times solution, 40% dimethoate 1000 times solution, 50% anti-Pu Wei WP 2000-3000 times solution or 50% malathion EC 1500-2000 times solution can be used alternately.
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