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Crops Fruits & nuts Lychee

Lychee (Litchi chinensis)

New Caledonia sent photos of a leaf curl symptom present on isolated trees of Litchi chinensis, sometimes killing them. It is also seen on Mangifera indica. It looks like the Erinose mite, but Eriophyes litchii is not (supposed to be) present and the under surfaces of the leaves do not show the brown velvet symptoms typical of the mite. Eriophyes magiferae is present in New Caledonia.

It is possible to detect the presence of Erinose mites by collecting a sample of the affected leaves in paper bags, leaving overnight to dry out and examining them under a microscope or x10 or, better still, x 20 hand lens, the next day. If Erinose mites are present, they emerge from the felt and their torpedo shaped bodies can be seen crawling on the surface.

The lack of the felting on the underside of the leaves, suggested that the problem was not due to lychee erinose mites. Another possibility was the broad mite, Polyphagotarsonemus latus (Banks). There would be evidence of these mites on the leaves if viewed under a microscope. However, it was thought unlikely that this mite’ could lead to the death of branches on mature trees. Can damage from a hormone herbicide such as 2,4 D be ruled out?