Characteristics and Control Methods of Spider Mite Disease in Orchids

Spider mites, also known as mites, come in many species. Take Schizotetranychus shi as an example: it is a common spider mite that damages orchids and other flowers. Its mouthparts attach to the underside of leaves, piercing through the leaf epidermis and spongy tissue layer into the leaf tissue, sucking the chloroplasts and cell contents of the palisade layer cells. It first damages the lower leaves, then gradually spreads to the upper leaves. Affected leaves develop small gray-white spots or white patches, and in severe cases the leaves wither and fall off.

Morphological characteristics: The adult female mite is oval, red, with a body length of 0.4 mm and a body width of 0.25 mm. There are black spots on each side of the body, and the legs and gnathosoma are white. The adult male mite is slightly smaller, with a body length of 0.24 mm and a body width of 0.1 mm.

Occurrence pattern: From early May to the end of October, especially during continuous drought and high temperatures in July to August, the population increases rapidly. If there are several consecutive days of rain, the population will decline significantly. It mainly damages the underside of leaves and has the habit of spinning silk webs. Eggs are mostly laid on both sides of the main vein on the underside of leaves and on the silk webs.

Control methods: During the damage period, spray with 40% dicofol emulsifiable concentrate at 1000 times dilution, or 50% parathion emulsifiable concentrate at 1500-2000 times dilution for control. Be sure to spray thoroughly, including the underside of leaves.