Disease Prevention and Control Methods and Key Technical Points for Oncidium
1. Mosaic disease
Symptoms: In the early stage, pale yellow spots appear on the leaves. Shortly afterward, the lesions cause leaf necrosis, forming sunken brown necrotic spots on the leaves, which gradually wither and die.
Solution: Promptly remove diseased leaves, avoid a high-temperature and high-humidity growing environment, and appropriately increase the application of phosphorus and potassium fertilizers. For affected plants, Bordeaux mixture or thiophanate-methyl solution can be sprayed.
2. Gray mold
Symptoms: Gray mold occurs on leaves and petals. The pathogen causes small spots on the petals, which then gradually expand into round brown lesions. In severe cases, the lesions spread across the entire petal, causing the flower to wither, and a gray mold layer appears on the leaves and petals.
Solution: Maintain good ventilation conditions, avoid the development of bacteria, and promptly spray fungicide.
Pest and Disease Prevention and Control Methods for Oncidium
The main pest of Oncidium is scale insects. Scale insects parasitize the leaf edges or leaf surfaces of the plant, sucking sap and causing the plant to wither; in severe cases, the entire plant will turn yellow and die. They can be killed by spraying with a 1000-fold dilution of 40% omethoate emulsifiable concentrate or a 2000-fold dilution of 50% malathion emulsifiable concentrate. The main diseases of Oncidium are soft rot and leaf spot. Leaf spot harms the leaves of Oncidium when it occurs, and soft rot can cause the entire plant to die. A 1000-fold dilution of 50% carbendazim or an 800-fold dilution of 50% thiophanate-methyl soluble wettable powder can be used for control.
Common Pests of Oncidium and Their Control Methods
Oncidium has many pests, but the most serious damage is caused by scale insects. There are many species of scale insects, and the degree of damage varies under different environments. Let us take a look!
Oncidium pest: Coffee brown scale
This scale insect is relatively small and gray or coffee-colored. It mainly parasitizes the leaves, mostly on the undersides, and feeds by sucking the sap of the plant. When coffee brown scale infestation is severe, the entire leaf is densely covered, which not only consumes the plant's nutrients but also causes sooty mold due to its excrement, affecting ornamental value.
Control method: Strengthen care, ensure timely ventilation, and promptly rinse with clean water when insects are found. When a large area is affected, pesticides can be sprayed once every 10 days, 1 to 3 times in total. Optional pesticides include omethoate and dichlorvos.
Oncidium pest: White peach scale
This is one of the most common pests of Oncidium. The insects are white, with white protrusions around the edges. The insect body is relatively small, 1.5 to 2 mm, and the damage is relatively serious. It mainly occurs on dwarf varieties of Oncidium. In severe cases, the leaves are covered with white, affecting photosynthetic nutrient accumulation.
Control method: When a small number of white peach scales are found, promptly scrape them off with a bamboo strip or wash them off with laundry detergent solution. If there are many white insects, promptly spray pesticides.
Oncidium pest: Barnacle scale
Barnacle scale is about 2 mm long and yellowish-brown. It attaches to both sides of the leaves and sucks sap, causing the leaf surface to lose its luster and affecting growth and ornamental value. Barnacle scale appears 2 to 3 times a year, with more serious occurrences in the second half of the year.
Control method: Maintain ventilation, control watering, and keep the leaves dry at night; promptly spray pesticides. For details, refer to coffee brown scale.