Light brown apple moth
The light brown apple moth (LBAM, Epiphyas postvittana) is a native ‘leaf-roller’ moth that has a wide host range, including numerous broadleaf weeds, horticultural crops and native species. While this moth is found across Australia, its impact on grape production varies significantly between regions, vineyards and seasons, making it important to take a strategic approach to management.
LBAM larvae (caterpillars) will feed on both foliage and fruit of grapevines. Whilst the feeding damage on bunch stems, flowers and berries can directly reduce crop yield, the most significant impact is the increased risk of infection by Botrytis cinerea and other bunch-rotting fungi. In addition, the larvae spin a protective cover of fine webbing on leaves or in immature grape bunches, which can trap debris inside the bunches and increase the potential for bunch rot development later in the season.
While LBAM will damage all commercial varieties of grapevine, the more susceptible varieties tend to be those that are also most susceptible to botrytis infection (e.g. tight-bunched, thin-skinned varieties). LBAM tends to be more of a problem in cooler wine regions, where summer conditions are relatively mild and the summer generation of moths is more likely to persist and cause subsequent damage to bunches. LBAM reproduces readily, with up to four life cycles annually.
A number of non-chemical control options are available. LBAM populations are kept below threshold levels in many vineyards by beneficial insect species, numbers of which can be promoted by avoiding use of broad spectrum insecticides. The wide host range of LBAM often produces an ‘edge effect’ in vineyards, where higher numbers of LBAM are evident closer to the boundaries of a block due to the presence of host plant species surrounding the block. This effect can be minimised by controlling weed species in and around the vineyard. However, when insect thresholds are exceeded and unacceptable levels of damage are imminent, chemical control (spraying) is often the only option left for growers.