Labor-Saving Method of Controling Citrus Leafminer at a Satsuma Mandarin Orchard Managed by Intentional Alternate Bearing Systems

Abstract

The effects of new nicotinic insecticides to control Citrus leafminer were examined at a Citrus orchard where satsuma mandarin ‘Aoshima Unshiu’ trees were grown under intentional alternate bearing systems. Among the insecticides, acetamiprid was more effective than imidacloprid in controlling Citrus leafminer when they were sprayed on trunk. The effective concentration was 1 to 2%. The effect of acetamiprid was enhanced by the addition of vinylacetate and diethylene glycol monoethyl ether. Acetamiprid was more effective when applied 10 days before summer pruning than when applied just after pruning. When injected into the soil, imidacloprid was more effective than acetamiprid. For a 10-year-old tree, imidacloprid at a rate of 0.5 g per tree, should be applied 10 days before pruning or on the pruning day. It seems that the effects of the insecticides persist for about 11 weeks after treatment. Compared to whole tree spraying, considerable labor will be saved, up to 65% in injection treatment, and up to 30% in trunk spraying.