How to control lychee erinose mite? A must-read for growers
The lychee erinose mite, also known as the lychee gall mite or lychee hair spider, causes the affected leaves to develop what is called felt disease. It damages lychee and longan. Both adult mites and nymphs attack tender shoots, leaves, flower clusters and young fruit, sucking sap. On affected leaves, yellow-green patches first appear on the underside; the damaged patches are sunken while the upper surface bulges, and dense fine hairs grow in the sunken areas, resembling felt - this is the so-called gall. The surface of affected leaves becomes distorted and uneven, and they may even dry up and fall off. After flower organs are damaged, they become deformed and swell into clusters and will not set fruit.
Life habits: More than 10 generations occur per year, and adult mites and nymphs overwinter among the hairs of the galls. Mite density is highest from May to June, and damage is more severe during this period of the year. At damaged sites the leaf surface bulges, and affected flower clusters have flower organs that swell like inverted bells into clusters. Within half a year of gall growth, mite density is at its highest. The erinose mite lives among the hairs of the galls, is more active when exposed to sunlight or rain, and crawls up and down among the hairs. Eggs are laid at the base of the hairs. The erinose mite prefers shaded environments with dense canopy and poor light; mite density is greater in the lower and inner parts of the canopy, and on leaves it is mostly found on the underside. The erinose mite can spread through nursery stock, insects, tools and wind. Lychee and longan propagation mostly uses air layering, so nursery stock is the main route by which the erinose mite spreads.
Control methods: 1. In winter, combine with pruning and cut off damaged branches and leaves. 2. From February to March, when galls first form on flower clusters and leaves, spray 0.2 degrees Baumé lime sulfur mixture, or use a mixture of 50% dichlorvos emulsion, 40% dimethoate emulsion and water (in a ratio of 1:1:2000), or 800-fold dicofol emulsion. 3. When transporting nursery stock, inspect and remove infested leaves to prevent the pest from spreading to new areas.