Pg. 24-27 Integrated management of litchi pests

In many years litchi trees often fail to mature a good crop. Possible reasons for this have been ascribed to a range of factors, such as nutrient deficiencies, high temperatures, moisture stress, etc. During 2008 up to 67% of the early drop of litchi fruit was caused by the coconut bug in a commercial Nelspruit orchard. The coconut bug prefers to feed on younger fruit and on another orchard where the relative seasonal abundance of this pest was monitored, early damage as high as 80% was recorded. Litchi moths begin to oviposit when the fruit begins to color visibly. This is the only time when control with a contact chemical will be effective, but unfortunately this occurs so close to harvest that unacceptably high residue levels could be expected. With this in mind, alternative control options were investigated. Isomate mating disruption dispensers of the oriental fruit moth were available and since the chemical composition of the pheromones of both species of moths were nearly identical, it was decided to evaluate this product in the field on a commercial basis. On both trial sites populations of the litchi moth were adequately suppressed. If these levels of control can be maintained during the 2009 season, this product will probably be registered. The advantage of using Isomate is that no pesticide comes in contact with the skin of the fruit, therefore no problems with pesticide residues are anticipated.