Calls are coming in about leafminer. It's there on the new growth, twisting and distorting it. In fact, it' been there most of the year. It was working new growth all winter long, because it was a warm winter. Right now, though, they are more active and more damage is being seen. So the question is what do you spray?...................................Nothing. Studies have been done that show little or no yield is affected by the infestation. It looks horrible and calls you to do something, but there's little that can be done. A trial we did 10 years ago involved almost weekly sprays of rotational materials on mature trees and it was impossible to keep the damage down. It happened. On young trees there are some possibilities, but even in this case it is tough.
Citrus leafminer larvae feed by creating shallow tunnels, referred to as mines, in young leaves. It is most commonly found on citrus (oranges, mandarins, lemons, limes, grapefruit and other varieties) and closely related plants (kumquat and calamondin). The larvae mine the lower or upper surface of the leaves causing them to curl and look distorted. Mature citrus trees (more than 4 years old) generally tolerate leaf damage without any effect on tree growth or fruit yield. Citrus leafminer is likely to cause damage in nurseries and new plantings because the growth of young trees is retarded by leafminer infestations. However, even when infestations of citrus leafminer are heavy on young trees, trees are unlikely to die.
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