Occurrence and Control Techniques of Common Pests and Diseases of Orchids

OrchidsDuring the cultivation process, they are often affected bypests and diseases, which not only reduces their ornamental value but in severe cases can even cause death.

1. Anthracnose. This disease is the most common disease of orchids, mainly affecting the leaves. In the later stage, small black spots appear on the lesions, eventually causing the diseased leaves to wither and turn yellow. The disease occurs mostly in May to June, during the plum rain season, or in years with much autumn rain or many typhoons in September to October. Control methods: (1) Promptly prune out diseased leaves and burn the diseased residues. (2) Improve the watering method, that is, slowly pour water in from the edge of the flower pot. (3) After new leaves sprout in winter, spray Bordeaux mixture (1:1:140) 1 to 2 times. In the early stage of the disease, spray 50% carbendazim 500 to 600 times dilution. At the same time, strengthen ventilation and light transmission, and avoid spraying water on the leaf surface.

2. Leaf blight. It mainly infects orchidFloralleaves. In the early stage, it appears as small reddish-brown spots, which then rapidly expand into oval or round dark brown lesions. When there are many lesions on the leaves, the leaf tissue between the lesions loses its green color and turns yellow and dies. Control methods: (1) Remove diseased leaves and diseased residues and burn them in a centralized manner. (2) Pay attention to ventilation and light transmission, prevent excessive watering, and avoid directly spraying or watering the plants. (3) Spray with 50% thiophanate-methyl 600 to 800 times dilution. Spray once about every 10 days, and 3 to 4 consecutive sprays are sufficient.

3. Southern blight. One of the main diseases of Cymbidium, caused by fungi. It occurs easily in hot and rainy seasons, often appearing in May and June, with July and August being the peak period of occurrence. Control methods: (1) Promptly remove diseased leaves, diseased plants, and diseased planting holes, and sprinkle and mix lime for disinfection; before planting, drench the potting soil with 30% Tumiaoxiao water agent 1000 times dilution. (2) In the early stage of the disease, spray and drench the roots with 1:500 chlorothalonil on the leaf surface.

4. Scale insects. Armored scales and mealybugs are the most common. The occurrence period is from April to October, and they occasionally occur in winter as well. Their reproductive capacity is extremely strong, and they can produce multiple generations in 1 year with overlapping generations, being most serious from May to October. Control methods: (1) When only a small number occur, they can be brushed off with a soft brush, then rinsed clean with water. (2) When there are many, spray 40% Supesha emulsion 1000 times dilution during the peak hatching period. When spraying, both the front and back of the leaves must be covered. Spray continuously 3 to 4 times, with an interval of 5 to 7 days each time, and they will basically be eliminated.

5. Red spider mites. Their reproductive capacity is strong and the damage is very serious. They are prone to occur during the high-temperature period from June to August.
Control methods: (1) If the number is small, they can be brushed off with a hairbrush or a small brush. (2) If there are many, use 40% dicofol 1000 times dilution to kill them. (3) A traditional method is to light one mosquito coil and place it in the pot of the diseased plant, then cover the pot together with a plastic bag. After 1 hour of fumigation, both eggs and adults are killed, and the plant is not affected.