Crop Pest Control Methods and Key Technical Points

1. Scale insects, commonly known as orchid lice, are the most common pest damagingorchids. After infestation, growth weakens and leaves wither, and their excrement also encourages mold growth, contaminating the leaves layer upon layer, hindering photosynthesis and affecting the normal growth and ornamental value of the orchid plant. When scale insects are found, they should be removed by hand brushing or the infested stems and leaves cut off. During the peak hatching period of the eggs, spray once every 10 days or so with 40% omethoate, or 50% phoxim, or 50% trichlorfon emulsifiable concentrate at 800-1000 times dilution, spraying 2-3 times consecutively. You can also use 20% dimethoate emulsifiable concentrate, diluted with water at 500-800 times, for spray control. In addition, tobacco stems or crushed garlic soaked in water for washing can also achieve a certain effect. 2. Aphids (green peach aphid, cotton aphid), thrips. Aphids like to suck leaf sap, and red spider mites damage orchid leaves by sucking a little of the epidermal tissue, causing small white spots to appear on the leaf surface. You can use 40% omethoate diluted 1000 times, spraying once every 5-6 days, several times consecutively, which can control all three of the above pests at the same time. In addition, lindane, or 2.5% deltamethrin emulsifiable concentrate diluted 4000 times can also be sprayed for control. 3. Red spider mite. Inorchidcultivation, red spider mites generally occur less often, but they also occur from time to time in places with strong sunlight, dryness and high temperatures. Red spider mites are relatively small, with a body length of less than 1 mm, red-brown or willow-yellow. Shaped like spiders, they can spin silk webs. Their reproductive capacity is very strong; above 30°C they can complete one generation in about 5 days, causing severe damage. Their piercing-sucking mouthparts pierce into the leaves to suck orchid sap, and the chlorophyll of the damaged leaves is destroyed. In severe cases, the leaves take on a grayish-yellow color or produce necrotic patches, causingorchidsto completely lose their ornamental and economic value. Common species include: red leaf mite, citrus red mite, brevipalpus mite, etc. In theorchid'scultivationmanagement, pay attention to ventilation and spraying water to increase humidity, and never leave dead corners. If water is never sprayed into a spot and it remains in a dry state for a long time, red spider mites are likely to occur, especially in the sunny spot of a heated room in winter, where this situation is most likely to appear. If the number is relatively small, you can brush and wash them off by hand. If the number is large, you can spray 40% dicofol at 1000 times dilution, which has a good effect; 80% dichlorvos emulsifiable concentrate and 40% omethoate at 1000 times dilution have a good effect on killing adults, but are ineffective against eggs, so several consecutive sprays are needed. 4. Whiteflies. Small in body, covered all over with a powdery substance, with wings and able to fly, but not good at flying. They are sometimes found damaging orchid species whose leaf cuticle is relatively thin. The piercing-sucking mouthparts of adults and larvae insert from the underside of the leaf, sucking the sap of the tissue, causing the leaves to turn yellow and wither, and brown rot disease occurs at the wound sites, and in severe cases the whole plant dies. Whiteflies have strong reproductive capacity and can form a huge population in a short time. Because their bodies are covered with a white waxy powdery substance, this brings difficulties to control. Common species include the greenhouse whitefly, etc. Spraying 25% deltamethrin, 10% dichlorethrin, 20% fenvalerate at 2000 times dilution gives good control results. Among these, 25% deltamethrin has the best effect; 40% dimethoate, omethoate, 80% dichlorvos, and 50% malathion emulsion have good control effects on adults and larvae, but are ineffective against eggs. If you want to kill the eggs, you need to apply the pesticide 2-3 times consecutively, with an interval of 5-6 days each time. 5. Snails and slugs. Snails and slugs are mollusks. Snails have a hard shell that protects their soft bodies, while slugs have no shell. These two types of animals mostly appear in year-round damp and dark orchid greenhouses, and by nature prefer shade and fear moisture, dryness and strong light. During the day they mostly hide in lightless, damp places, and come out at night to gnaw on young orchid leaves, young roots and flowers and other parts. Because their food intake is very large, they can often eat an entire Cattleya flower beyond recognition in a single night. Once they occur in large numbers, the damage is relatively severe. When you see bright, transparent slime trail marks on leaves, pot edges and benches, it indicates that this type of mollusk is active. Control methods: (1) Poison bait trapping: mix bran with arsenic, trichlorfon, etc., and scatter it in the places where they are often active. Around the orchids, on the benches and flower pots, spray pesticides such as trichlorfon and deltamethrin, or scatter quicklime or saturated salt water. (3) Pay attention to cleanliness in the site and promptly remove dead branches and fallen leaves. 6. Earthworms. People think earthworms can improve soil structure and make potting soil loose and breathable, which is beneficial to orchid root growth. Little do they know that orchid roots are sweet, which exactly suits the earthworm's appetite, and their gnawing of orchid roots does more harm than good. They should be eliminated and controlled. Line the bottom of the pot with brick or stone, or use coir and palm fiber to block the drainage hole at the bottom of the pot. After discovering them, pour dimethoate diluted 2000 times with water into the pot, and after the earthworms come out, wash with clean water, or pour soap pod water into the pot, or repot and change the soil. 7. Ants. Ants enter the pot and make holes, damaging orchid roots. The method of driving them away is the same as above, or use oily and fishy food to lure them into a group and then capture and kill them.