Spray application – doing it better

The following tips for improving agrochemical application, courtesy of AWRI Senior Viticulturist Marcel Essling, may help your program achieve optimum pest and disease control results this season.

  1. Review last season’s spray program – Consider pest and disease monitoring results and relevant comments from your wine buyer to understand how well the program performed. If control of one disease or pest was not adequate, consider how control can be improved. The three Ts rule of applying the right treatment, at the right time, using the right technique hold true.
  2. Keep on changing – During the growing season, vineyard canopy size changes markedly. Be prepared to modify the spray unit set-up in response to vine size and target (e.g. grape bunch zone). Water and air volume, as well as nozzle size and direction, even tractor speed, may need to change from one spray to the next. Before concentrate spraying, remember that some products need time to be absorbed into plant tissue in order to be effective (refer ‘useful resources’).
  3. Keep your spray plan flexible – Have a spray plan that sets out which agrochemicals to apply at key growth stages for relevant pests and diseases. Being able to respond to weather extremes and unexpected seasonal conditions can be a logistical challenge in some seasons. Having access to adequate chemical stock and being able to shorten the spray interval based on pest/disease pressure and weather can be critical.
  4. Check the weather – the Bureau of Meteorology provides a number of useful forecasting resources such as MetEye that growers should become familiar with. Some wine regions also provide e-alerts to pest and disease outbreaks.
  5. Check your coverage! – Combinations of water sensitive papers, florescent dye, kaolin clay products (suncreens) or even food colouring on rolled out cash register paper assist greatly in assessing coverage and to help see if you’re actually hitting your target.
  6. Follow the label directions – Pesticide chemical labels contain important information about how to use products safely and in accordance with legal requirements. When choosing chemicals, consider the requirements of your grape purchaser. If growing grapes for export, follow the recommendations in the AWRI’s ‘Dog book’.
  7. Be aware of spray drift – Weather conditions such as wind, temperature and relative humidity significantly influence the likelihood of drift. Delta T (ΔT) is a measure that captures the combined effects of temperature and humidity, and indicates if conditions are suitable for spraying (refer ‘useful resources’).
  8. Check your spray water quality – water pH, total hardness, bicarbonate levels and salinity (EC) are important to measure and, if required, adjust prior to adding chemical to the tank. If you’re unsure of performance of an agrochemical in your situation, consult the manufacturer or on-seller for guidance.
  9. Avoid agrochemical resistance – Pests and diseases can develop resistance to chemicals if not applied appropriately. Growers are advised to follow the strategies developed by CropLife Australia, which are set out at the back of the AWRI’s ‘Dog book’. If you suspect that you may have a resistance issue, contact your local Department of Primary Industries representative or the AWRI for further assistance.

Useful resources:



For more agrochemical replated advice, contact the AWRI helpdesk on 08 8313 6600 or viticulture@awri.com.au.

For more information from AGWA, contact Adrian Loschiavo, AGWA R&D Program Manager, Adrian.Loschiavo@agwa.net.au.