Getting the Drift on Summer Weed Spraying

Farmers across Australia, and particularly in the Mallee, are being reminded to monitor their summer weed control, as local grapevines are at a delicate stage of fruit development.

While summer weed spraying is an important part of agricultural production, Agriculture Victoria has reported off-target spray-drift poses a significant risk to horticultural crops.

Agriculture Victoria Biosecurity Area Manager for the Northern Region Ben Perry said both industries are important contributors to the local economy and need to be able to coexist in the region.

Mr Perry said there are serious risks associated with inversion drift as spray droplets trapped within an inversion layer will tend to remain suspended until the relatively slow moving air breaks up and releases the trapped droplets.

“One of the biggest risks to horticulture comes from ‘inversion drift’, where damage from spraydrift can occur many kilometres from the area being sprayed.

“Spray droplets trapped in an inversion layer can travel significant distances, so grain growers need to be mindful of not just their immediate neighbours, but those further afield too.

“And with grapevines at this time of year being particularly sensitive to Group 1 herbicides, such as 2,4-D and MCPA, it’s really important that chemical users spray to the weather conditions of the day.

“Drift can injure foliage and fruit, reduce yield, fruit quality and in severe cases result in the eventual death of grapevines.

“There are also serious risks associated with unacceptable chemical residues in fruit produced on affected vines, which can affect the domestic and international wine trade” he said.

With summer weed spraying now underway and continuing through to mid autumn, Agriculture Victoria suggests farmers check their spraying methods and regimes, answering the following questions:

• Does the intended chemical use follow label directions? • Are there Agricultural Chemical Control Area (ACCA) restrictions currently in place? • What are the current weather conditions? (Such as wind speed and direction, likelihood of a temperature inversion, etc.) • Is the spray equipment suitable for the chemical being sprayed? (Such as appropriate nozzle types and operating pressure) • Is spraying taking place at the appropriate time of day? • Are there crops (grapevines or any other crop) in the immediate vicinity which are sensitive to the intended chemical? • Are adequate records being kept?

Any growers who suspect they may have been affected by spray drift are encouraged to contact the Agriculture Victoria Customer Service Centre on 136 186 and ask to speak to their nearest Chemical Standards Officer.

For more information on inversion layers, spraying tips or reporting spray drift visit agriculture.vic.gov.au.