Series 1 of Watermelon Pest and Disease Control Methods
One of the Methods for Controlling Watermelon Pests and Diseases
Anthracnose is a fungal disease that mainly affects watermelon and also affects melon. It can occur during the growing season and during storage and transport after harvest, with most cases occurring in the mid-to-late growth stage.
After the disease occurs at the seedling stage, brown round or semicircular lesions appear on the edges of the cotyledons, with small black dots or pale red sticky material on them, and the seedlings damp off . When leaves are affected, they first show water-soaked spindle-shaped or round pale yellow lesions, which quickly turn into black round spots with a purple ring around the outside , sometimes showing concentric rings. On stems and leaf stalks, the lesions are oblong and slightly sunken, first water-soaked yellowish brown, then black . On the fruit, dark green oil-soaked small spots first appear, and after expanding they become round or oval sunken depressions, dark brown, with many small black dots arranged in a ring on the lesions. When humid, a pink sticky substance oozes from them, and young fruit often become deformed after infection. The pathogen overwinters in diseased residues in the soil or on seeds, and infected seeds can directly invade the cotyledons.
The control measures are as follows: carry out a 3-4 year rotation, and do not use contaminated fertilizer. Soak seeds in 100 times formalin solution for 30 min, wash them clean and then sprout them, or soak seeds in 55°C warm water for 5 min. Apply more phosphorus and potassium fertilizer, pay attention to drainage, and place straw under the fruit as a cushion. In the early stage of the disease, remove diseased leaves and vines and bury them deeply. Spray 50% carbendazim 1000 times solution, or 1:1:200 Bordeaux mixture, or 75% chlorothalonil 6 00 times solution, once every 7-10 days, for 3 consecutive sprays.
Fusarium wilt can occur at all growth stages, with the most cases from vine extension to the middle fruiting stage. Infection at the seedling stage causes damping off. When mature plants are affected, the lower leaves turn yellow and gradually spread upward; at first they wilt during the day and recover in the morning and evening, and after several days the whole plant dies. The stem and root system show water-soaked rot, turn brown, and sometimes pink mold appears, while the vascular bundles do not turn brown.
The pathogen survives in the soil for 5-6 years, and it can still remain viable after passing through the digestive tract, so barnyard manure can also carry the pathogen. The pathogen invades through root wounds or the tips of root hairs, develops in the vessels, affects water transport, and causes the plant to wilt. The disease is severe in low-lying areas, with poor drainage, insufficient low fertilizer, excessive nitrogen fertilizer, flood irrigation and continuous cropping.
The control measures are as follows: carry out a 7-8 year rotation. Immediately pull out and burn diseased plants, and disinfect the diseased holes with 50% amobam 400 times solution. Choose disease-resistant varieties, use pumpkin or gourd as rootstock for grafting, or drench the root zone with 70% dexon original powder, using 200-250 ml of liquid per plant. You can also mix 1 part dexon original powder with 20 parts flour into a paste and apply it to the base of the stems and vines of diseased plants.
The black cutworm is also called soil silkworm or root-cutting worm. It has 2-7 generations a year, and in most areas the first generation causes serious damage. Adults rest in weeds or cracks in clods during the day, and feed, mate and lay eggs at night; adults have strong chemotaxis and phototaxis. Larvae have 6 instars; before the 3rd instar they are mostly in the host heart leaves or on the soil surface and in soil cracks, feeding on the host's tender leaves day and night; 4th-6th instar larvae hide in the soil during the day and cause damage at night, biting off tender stems or tender tips of seedlings at ground level. The suitable temperature for the growth and development of the black cutworm is 13-25°C, and the soil water content is 15%-20. Damage is severe in low-lying areas, heavy clay soil, and places overgrown with weeds. Plowing the land in winter and spring eliminates some egg masses, overwintering pupae and larvae. In the early morning, manually open the surface soil near broken seedlings to catch and kill older larvae. Use paulownia leaves to attract and kill them: collect fresh paulownia leaves, soak them in water, and place them in the affected field in the evening during the first-generation larval stage, relying on a certain odor released by paulownia leaves to attract black cutworms to feed. Fresh vegetable leaves or small piles of weeds can also be used for attraction. When the larvae are older, use 50% diazinon emulsion 1000-1500 times solution, or 50% phoxim emulsifiable concentrate for root drenching.
Both adults and larvae of the yellow squash beetle can cause damage. The larvae bite fine roots or bore into the pith and stems near the ground, causing poor seedling growth, yellowing and even death. Adults feed on leaves, flowers and fruits, biting many round or semicircular notches; damage is severe at the seedling stage, and they often eat all the leaves.
In the early morning when the dew has not dried, handpick and kill them. Use plastic film mulching, or scatter plant ash, chaff, sawdust around the plants to prevent adults from laying eggs and reduce larval damage. Spray 90% trichlorfon 800 times solution to control adults, and use 2000 times solution for root drenching to kill larvae. In addition, there are also damage from melon aphids and root maggots.
After the disease occurs at the seedling stage, brown round or semicircular lesions appear on the edges of the cotyledons, with small black dots or pale red sticky material on them, and the seedlings damp off . When leaves are affected, they first show water-soaked spindle-shaped or round pale yellow lesions, which quickly turn into black round spots with a purple ring around the outside , sometimes showing concentric rings. On stems and leaf stalks, the lesions are oblong and slightly sunken, first water-soaked yellowish brown, then black . On the fruit, dark green oil-soaked small spots first appear, and after expanding they become round or oval sunken depressions, dark brown, with many small black dots arranged in a ring on the lesions. When humid, a pink sticky substance oozes from them, and young fruit often become deformed after infection. The pathogen overwinters in diseased residues in the soil or on seeds, and infected seeds can directly invade the cotyledons.
The control measures are as follows: carry out a 3-4 year rotation, and do not use contaminated fertilizer. Soak seeds in 100 times formalin solution for 30 min, wash them clean and then sprout them, or soak seeds in 55°C warm water for 5 min. Apply more phosphorus and potassium fertilizer, pay attention to drainage, and place straw under the fruit as a cushion. In the early stage of the disease, remove diseased leaves and vines and bury them deeply. Spray 50% carbendazim 1000 times solution, or 1:1:200 Bordeaux mixture, or 75% chlorothalonil 6 00 times solution, once every 7-10 days, for 3 consecutive sprays.
Fusarium wilt can occur at all growth stages, with the most cases from vine extension to the middle fruiting stage. Infection at the seedling stage causes damping off. When mature plants are affected, the lower leaves turn yellow and gradually spread upward; at first they wilt during the day and recover in the morning and evening, and after several days the whole plant dies. The stem and root system show water-soaked rot, turn brown, and sometimes pink mold appears, while the vascular bundles do not turn brown.
The pathogen survives in the soil for 5-6 years, and it can still remain viable after passing through the digestive tract, so barnyard manure can also carry the pathogen. The pathogen invades through root wounds or the tips of root hairs, develops in the vessels, affects water transport, and causes the plant to wilt. The disease is severe in low-lying areas, with poor drainage, insufficient low fertilizer, excessive nitrogen fertilizer, flood irrigation and continuous cropping.
The control measures are as follows: carry out a 7-8 year rotation. Immediately pull out and burn diseased plants, and disinfect the diseased holes with 50% amobam 400 times solution. Choose disease-resistant varieties, use pumpkin or gourd as rootstock for grafting, or drench the root zone with 70% dexon original powder, using 200-250 ml of liquid per plant. You can also mix 1 part dexon original powder with 20 parts flour into a paste and apply it to the base of the stems and vines of diseased plants.
The black cutworm is also called soil silkworm or root-cutting worm. It has 2-7 generations a year, and in most areas the first generation causes serious damage. Adults rest in weeds or cracks in clods during the day, and feed, mate and lay eggs at night; adults have strong chemotaxis and phototaxis. Larvae have 6 instars; before the 3rd instar they are mostly in the host heart leaves or on the soil surface and in soil cracks, feeding on the host's tender leaves day and night; 4th-6th instar larvae hide in the soil during the day and cause damage at night, biting off tender stems or tender tips of seedlings at ground level. The suitable temperature for the growth and development of the black cutworm is 13-25°C, and the soil water content is 15%-20. Damage is severe in low-lying areas, heavy clay soil, and places overgrown with weeds. Plowing the land in winter and spring eliminates some egg masses, overwintering pupae and larvae. In the early morning, manually open the surface soil near broken seedlings to catch and kill older larvae. Use paulownia leaves to attract and kill them: collect fresh paulownia leaves, soak them in water, and place them in the affected field in the evening during the first-generation larval stage, relying on a certain odor released by paulownia leaves to attract black cutworms to feed. Fresh vegetable leaves or small piles of weeds can also be used for attraction. When the larvae are older, use 50% diazinon emulsion 1000-1500 times solution, or 50% phoxim emulsifiable concentrate for root drenching.
Both adults and larvae of the yellow squash beetle can cause damage. The larvae bite fine roots or bore into the pith and stems near the ground, causing poor seedling growth, yellowing and even death. Adults feed on leaves, flowers and fruits, biting many round or semicircular notches; damage is severe at the seedling stage, and they often eat all the leaves.
In the early morning when the dew has not dried, handpick and kill them. Use plastic film mulching, or scatter plant ash, chaff, sawdust around the plants to prevent adults from laying eggs and reduce larval damage. Spray 90% trichlorfon 800 times solution to control adults, and use 2000 times solution for root drenching to kill larvae. In addition, there are also damage from melon aphids and root maggots.