Grapevine scale biology and monitoring in Australian vineyards

Summary

Objective

This project aims to address key research gaps on scale insects in Australian winegrape vineyards, equipping growers with the knowledge needed to implement sustainable and effective management strategies for these challenging pests. A combination of field, laboratory and greenhouse studies will be used to: 

• identify the key scale insect species and map their distribution in Australian winegrape vineyards
• understand the biology of scale insects, focusing on crawler emergence timing, number of generations per year, and the activity of natural enemies, to inform region-specific management strategies
• evaluate the effectiveness and impact of current vineyard management strategies on scale pest populations, to identify successful methods and areas for improvement in pest control practices
• test various pesticides on different life stages of scale insects to optimise chemical application timing and effectiveness.

Background

Grapevine scale have been increasing in prevalence over the past decade and have become a serious challenge in some Australian wine regions. Scale are soft-bodied insects that feed on plant sap - high numbers in a vineyard can significantly reduce vine health and grape yield and even cause vine death. Honeydew and sooty mould caused by scale can also be a visual blight on winegrapes and lead to fruit rejection by wineries. Scale also spread grapevine viruses, compounding their impact on vine health and productivity.

Despite their significant impact, controlling scale in grapevines remains challenging with existing agrichemicals. This is due to concerns over wine residues and export market tolerances, restrictions for resistance management, and the insects' ability to overwinter beneath the bark of canes and cordons. The reasons for the rise in scale insect issues are unclear but may include warmer winter and spring temperatures, shifts in dominant scale species, and changes in spray programs that reduce natural enemy populations. Poor vine nutrition and decline may also contribute, as stressed vines are generally more susceptible to pests and diseases.

Late in 2023, Wine Australia convened two workshops for researchers and industry practitioners to share current knowledge on management of scale in vineyards, define and confirm the problems to be solved and identify priorities for new investment. The result was a three-year project led and co-funded by the South Australian Research and Development Institute (SARDI), in partnership with the University of Adelaide, the Australian Wine Research Institute, and the Australian National University. 

Sector benefits

This project will deliver significant benefits to the Australian wine sector by addressing critical knowledge gaps and developing sustainable management solutions for soft scale insects, a growing threat to vine health and productivity. More effective and targeted management options for scale will reduce crop losses, decrease fruit rejection, improve vine health, and minimise the risk of virus spread, ultimately enhancing vineyard productivity, profitability and sustainability. Enabling growers to use pesticides more effectively will reduce residue risks and protect market access, and identification of new options will minimise reliance on broad-spectrum insecticides. In addition, partnership between leading research organisations will retain technical capability in the sector, maximise the likelihood of robust solutions and facilitate effective knowledge transfer to end-users.