Removal of bunches or spikelets is not effective for the control of aceria guerreronis

Abstract

Worldwide, there remains a reliance on repeated chemical applications as a control strategy for the coconut mite, but these are impractical, not economical, and environmentally hazardous. In this study, the damage severity of Aceria guerreronis on coconut fruits was studied under different conditions to investigate the effects of bunch management on the amount of damage to newly produced bunches. The damage was evaluated using a diagrammatic scale under four different conditions: 1) plants with bunches removed; 2) bunches with the distal portion of the spikelet removed; 3) bunches sprayed monthly with abamectin (9 g a.i./ha); and 4) control plants. For each treatment, two fruits from bunches 1 to 6 (counted from the last open inflorescence) from 10 plants were randomly collected every month for 4months. The removal of the distal portion of the spikelets had no effect on the damage level of new bunches but delayed the damage severity by ≈1 month. After the removal of all of the bunches, the damage severity was restored within 2 months to the newly produced bunches, whereas the chemical control with abamectin kept the A. guerreronis damage intensity at a low level. Thus, the removal of bunches or the distal portion of spikelets is not an effective practice for the control of A. guerreronis in areas with high levels of infestation.