Detailed Guide to Common Pest and Disease Control Methods for Orchids
Orchids are one of the favorite plants grown by flower enthusiasts, and also one of the plants most prone to diseases. Below, we share common pest and disease control methods for orchids.
Common Pest and Disease Control Methods for Orchids
1. Red spider mite: Mostly occurs in places with strong light, dry conditions and high temperatures. It reproduces quickly, with 14 to 18 generations per year, causing severe damage. Affected plants have yellowed leaves or necrotic patches, completely losing their ornamental value, and some even die entirely.
Control measures: Pay attention to ventilation and spraying water to increase humidity; if there are only a few pots, manual brushing and washing can be used; for larger quantities, spray with 40% dicofol, 80% dichlorvos or 40% omethoate at 1000 times dilution, with good control results.
2. Leaf miner: Diptera. Paphiopedilum parishii and Paphiopedilum hirsutissimum are the most severely affected. The larvae feed on the leaf mesophyll beneath the leaf epidermis, destroying leaf tissue and affecting ornamental value. Moreover, the damaged areas are prone to black rot, causing the entire leaf and plant to rot.
Control measures: In the early stage of larval damage, spray with 40% omethoate, 80% dichlorvos or 25% phosmet at 1000 times dilution, spraying once every 7 days or so. Spray 2 to 3 times consecutively for good control results.
3. Whitefly: Small in size, with powdery substance covering the entire body. Orchid species with relatively thin leaf cuticles are most susceptible. They cause leaves to turn yellow and wither. Brown rot easily occurs at wound sites, and even the entire plant may die. Whiteflies have strong reproductive capacity and can form huge populations in a short time. Because their bodies are covered with white waxy powdery substance, control is difficult. Common species include: greenhouse whitefly, spiny whitefly, citrus green whitefly, and citrus black whitefly.
Control measures: Spray with 2.5% deltamethrin or 20% fenvalerate at 2000 times dilution; or 40% dimethoate emulsifiable concentrate at 800 times dilution, 80% dichlorvos at 800 to 1000 times dilution, 50% malathion at 800 times dilution, for good control results.
4. Scale insects: Armored scales and mealybugs are the most common. The occurrence period is from April to October, with occasional occurrences in winter. Their reproductive capacity is extremely strong, with multiple generations per year and overlapping generations, being most severe from May to October.
Control methods: (1) When few occur, they can be brushed off with a soft brush and then rinsed clean with water. (2) When there are many, spray with 40% methidathion emulsifiable concentrate at 1000 times dilution during the peak hatching period. When spraying, both the front and back of leaves should be covered, spraying 3 to 4 times consecutively with 5 to 7 day intervals, and they will basically be eliminated.
5. Anthracnose: An important disease of orchids. In the early stage, circular dark brown spots appear on leaves, which gradually expand with dark brown edges and grayish-white centers. The spots are prone to cracking. In severe cases, spots are numerous and leaves turn yellow and wither.
Control measures: (1) Cut off diseased leaves and remove diseased debris, and burn them in a centralized manner; (2) Pay attention to ventilation and light penetration; (3) Cultivate robust plants to reduce disease occurrence, prevent excessive watering, and especially avoid directly spraying water on plants; (4) For affected plants, spray with 50% benomyl and 70% thiophanate-methyl or 50% carbendazim at 600 to 800 times dilution, once every 10 days or so, spraying 3 to 4 times consecutively, for good control results.
6. Leaf blight: Mainly attacks orchid leaves. In the early stage, small reddish-brown spots appear, which rapidly expand into oval or circular dark brown lesions. When there are many lesions on a leaf, the leaf tissue between the lesions loses its green color and turns yellow and dies.
Control methods: (1) Remove diseased leaves and diseased debris and burn them in a centralized manner. (2) Pay attention to ventilation and light penetration, prevent excessive watering, and avoid directly spraying water on plants. (3) Spray with 50% thiophanate-methyl at 600 to 800 times dilution, once every 10 days or so, spraying 3 to 4 times consecutively.
7. Southern blight: One of the main diseases of Cymbidium, caused by fungi. It easily occurs in hot and rainy seasons, often appearing in May and June, with the peak period in July and August.
Control methods: (1) Timely remove diseased leaves, diseased plants and diseased planting holes, and sprinkle lime for disinfection; before planting, drench the potting soil with 30% tumiaoxiao water solution at 1000 times dilution. (2) In the early stage of disease, spray chlorothalonil at 1:500 dilution on leaf surfaces and pour it at the roots.