The answer to effective, long-term vineyard pest control could be available in your local plant nursery – and not in the form of a pesticide – new research suggests.
The research, undertaken by Dr Mary Retallack as part of her PhD, supported in part with a Wine Australia scholarship, found that biological control and the use of locally-adapted native insectary plants could potentially provide sustainable solutions for grapegrowers.
Dr Retallack evaluated three native plants – Christmas bush, Bursaria spinosa, prickly tea-tree, Leptospermum continentale and wallaby grasses, Rytidosperma spp. – in the Adelaide Hills, Barossa Valley and Eden Valley to determine their capacity to support populations of predatory arthropods, or ‘natural enemies’ in vineyards.
‘Insectary plants provide food, shelter and alternative prey/hosts, that nourish and support the presence of predatory arthropods’, said Dr Retallack, Viticulturist and Managing Director of Retallack Viticulture Pty Ltd.
Her research showed that native plants can be a rich source of insects – the number of visually distinct species in the native plants that she studied was nearly double than the number found in grapevines alone.
Simply by planting each of the native species in and around vineyards, it was possible to increase the diversity of ‘predatory arthropods’.
In the case of Christmas bush and prickly tea-tree by more than three times – and a net increase of around 27 per cent when wallaby grass was included.
‘The findings are exciting, because the insectary plants we studied are naturally adapted to all of the major wine growing regions within Australia and could potentially be planted virtually wherever wine grapes are grown’, said Dr Retallack.
A second aim of the research was to clarify whether light brown apple moth (LBAM), Epiphyas postvittana is the main lepidopteran[1] pest of grapevines in vineyards – and thus the key insect pest causing economic damage in Australian vineyards.
Indeed, Dr Retallack found it was.
Importantly, the study also revealed for the first time that larval Acropolitis rudisana, lucerne leafroller, Merophyas divulsana, and cotton tipworm, Crocidosema plebejana can be found on the grapevine canopy in South Australian vineyards at low densities.
‘As these pests are closely related to LBAM, it is anticipated they can be managed through existing integrated pest management (IPM) strategies’, Dr Retallack said.
‘These lepidopteran species may provide a valuable source of alternative hosts for parasitoid wasps and alternative prey for predators, if the larvae are predominantly located in vineyard mid-rows and don’t migrate to the grapevine canopy.’
Dr Retallack said if LBAM damage could be minimised, this could potentially reduce the impact of Botrytis and other bunch rots – which is estimated to cost the Australian wine sector tens of millions of dollars each year.
Message for growers
Dr Retallack said there were a number of practical measures growers could take to manage pests while enhancing the biodiversity of their vineyards.
‘Within a vineyard, existing vegetation structures such as windbreaks, vegetation corridors, beetle banks, mid-row, under-vine and headland plantings can be enhanced to provide resources for predators that contribute to pest control throughout the year’, she said.
She encouraged vineyard managers to explore the use of locally-adapted insectary plants in their vineyard.
‘The opportunity to plant selected native insectary species could help wine grape growers save time and resources by producing fruit with lower pest incidence, while enhancing biodiversity of their vineyards.’
[1] The lepidoptera is the order of insects that includes butterflies and moths.