Improved management of garden weevil in WA – A warning service and assessing exclusion bands

Abstract

This project aimed to determine whether area-wide sentinel monitoring of garden weevil is useful in advising vignerons of the timing of trunk drenching and to assess the efficiency of artificial fibre trunk bands in excluding weevils from the vine canopy.

Summary

Garden weevil is an important pest of winegrape vineyards in the southern growing regions of Australia. A strategic method of protecting vines is to apply a trunk drench of insecticide before weevil entry into the canopy. Also, some vignerons have been using artificial fibre trunk bands in an attempt to prevent weevils entering the vine canopy.

Vignerons involved in monitoring of garden weevil emergence were selected to be representative of the infested area in Western Australia. Results of the monitoring were reported to the industry via the internet. They showed the timing of spraying varied both within and between regions and that individual vineyard monitoring is the best approach on which to base decisions for the need and timing of insecticide to control garden weevil. There was a range in attitudes among vignerons on the pest status of garden weevil and the need for insecticide. This supported the view that individual vineyard monitoring is essential for garden weevil management according to each vigneron’s management philosophy.

The study on the role of exclusion trunk bands was inconclusive in field trials because of low weevil abundance in study sites. Laboratory studies confirmed earlier observations that artificial fibre trunk bands have limited effect on preventing weevils from entering the vine canopy. This is at variance to the experience of some vignerons who have had success with weevil management where the bands have been used. Further studies are required to clarify this anomaly.