Orchid Pest and Disease Control Methods and Key Technical Points

I. Anthracnose

This disease is the most common disease of orchids, mainly affecting the leaves. In the later stages, black dots appear on the lesions, eventually causing the diseased leaves to wither and turn yellow. The disease occurs frequently from May—June, during the plum rain season, or in years with abundant autumn rain or frequent typhoons from September—October.

Control methods: (1) Promptly prune out diseased parts and burn the diseased plant debris. (2) Improve the watering method, that is, slowly pour water in from the edge of the flower pot. (3) After new leaves emerge in winter, spray Bordeaux mixture (1:1:140) 1—2 times. In the early stage of the disease, spray 50% carbendazim 500—600 times dilution. At the same time, strengthen ventilation and light transmission, and avoid spraying water on the leaf surface.

II. Leaf blight

It mainly attacks orchid leaves. 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 plant debris and burn them in a centralized manner. (2) Pay attention to ventilation and light transmission, prevent excessive watering, and avoid directly spraying or pouring onto the plants. (3) Spray with 50% thiophanate-methyl 600—800 times dilution. Spray once about every 10 days, and 3—4 consecutive sprays will be sufficient.

III. 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 the disease.

Control methods: (1) Promptly remove diseased leaves, diseased plants, and diseased planting holes, and sprinkle mixed 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 the leaf surface and irrigate the roots with 1:500 chlorothalonil.

IV. Scale insects

Armored scales and mealybugs are the most common. The occurrence period is from April—October, and they occasionally occur in winter as well. Their reproductive capacity is extremely strong, and they can produce multiple generations in one year with overlapping generations. They are most severe from May—October.

Control methods: (1) When only a small number occur, they can be brushed off with a soft brush and then rinsed clean with water. (2) When there are many, spray 40% Supracide emulsifiable concentrate 1000 times dilution during the peak hatching period. When spraying, both the front and back sides of the leaves must be sprayed. Spray continuously 3—4 times, with an interval of 5—7 days each time, and they will basically be eliminated.

V. 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—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 folk method is to light one mosquito coil, place it in the pot of the diseased plant, and cover the pot together with a plastic bag. After fumigating for 1 hour, both eggs and adults are killed, and the plant is not affected.