Lychee erinose mite
Erinose mites cause hairy, blister-like galls on the upper side of the leaves, thickening, wrinkling and distorting them, and brown, felt-like wool on the underside. The mites feed on 'felt' the underside of the leaves. The production of erinose disrupts the ability of the leaves to photosynthesise.
|Description of adult|
The active stages and eggs are very small and may be difficult to find even with a x10 magnification hand-lens.
Adult mites migrate from older infested leaves to infest young leaves. They lay eggs on these leaves and the young hatch in 3-4 days. The life cycle is completed in 13 days under favourable conditions. The adults live in the velvety erinose produced on leaves as a reaction to their feeding. As trees produce new leaf and flower flushes, the mites migrate to these where they establish new pockets of erinose in which to feed and shelter.
Major and frequent pest of foliage, flowers and fruit.
Lychee erinose mite is a serious pest that deforms the plant and produces reddish-brown velvety growth on the underside of the leaves. In severe cases flowers are destroyed and fruit-setting prevented. The mites are invisible to the naked eye and live on the underside of the leaves amongst the erinose.
Heavy infestations of the foliage reduce photosynthetic activity and so debilitate the tree. New flushes do not get the chance to contribute energy to the tree if they are infested immediately they emerge. Heavy infestations on foliage below flower panicles will inevitably result in flower damage with the likelihood that little or no fruit will set. Set fruit may also be damaged cosmetically.
Examine 20 trees widely spaced throughout the crop. If erinose is evident on the trees, each new growth flush should be sprayed at least three times with a suitable miticide at 10-14 day intervals.
Prune as much of the infested foliage from the tree as possible and destroy it. The mite is easily spread on nursery plants especially marcots taken from infested trees. Use only clean, mite-free planting material. Where possible obtain your planting material from mite-free orchards and dip the trees in miticide before planting out. Wind and bees can also spread these mites.
Several predatory mites and a fly larva prey on the erinose mite. However, none of these native Australian predators is able to control the pest.
Satisfactory control can be achieved with a strict program of three successive sprays of a suitable miticide targeting the growth flushes. The first spray should be applied to infested trees and their neighbours as a new flush begins to emerge. The second spray is applied when the flush has fully emerged and just before the new leaves start to expand. The third spray should be applied after the new leaves have fully expanded but have not hardened off.
Chemical registrations and permits
Check the Australian Pesticides & Veterinary Medicines Authority chemical database and permit database for chemicals registered or approved under permit to treat this pest on the target crop in your State/location. Always read the label. Always observe withholding periods.