Grape growers and the Department of Primary Industries (DPI) are urging broadacre farmers using phenoxy herbicide products containing 2,4-D and MCPA, to be vigilant in managing the risk of spray drift.
Grapevines and other broadleaf crops are highly vulnerable to spray drift damage from phenoxy herbicides, and DPI has recently received information from vine growers who have observed phenoxy herbicide damage in their vines.
It is possible for small amounts of off-target spray drift to impact on susceptible crops kilometres from the target area if they are not applied under suitable conditions.
To put this into perspective, as little as three quarters of a gram per hectare of 2,4-D can have a damaging affect on grape vines.
To assess suitable spray conditions chemical users need to monitor and consider the weather, use buffer zones if necessary, identify nearby susceptible crops and sensitive areas and ensure spray equipment is in good working order. Liaising with your neighbours should be included in preparation to spray.
In monitoring the weather chemical users must be aware of the potential for atmospheric inversions, which occur most commonly in the morning or during the night. Fine droplets and vapours can be trapped in the inversion and transported well away from the target area.
DPI recommends spraying with winds of between 3-15 km/hr and blowing away from sensitive plants, with the slight turbulence caused by the breeze combing the chemical into the target.
The opposite occurs in still air. Fine droplets can remain suspended in the air for a significant time, increasing the risk of them moving off-target. Ensuring an appropriate droplet size is a major consideration when using all agricultural chemicals, and for 2,4-D products in particular, using a coarse to very coarse spray quality is mandatory.
Like 2,4-D, many chemical products have similar droplet size restrictions, therefore it is essential to read and follow label directions strictly.
It is illegal to use ester 2,4-D products in Agricultural Chemical Control Areas (ACCAs) when they are in operation. The Mallee Mid-Murray ACCA and the Extended Mallee ACCA operate from August 1 each year until April 30 the following year.
It is also an offence under the Agricultural and Veterinary Chemicals (Control of Use) Act 1992 to cause damage to plants or contamination to agricultural produce from spray drift, which can incur penalties of more than $20,000.
For information on ACCA locations and chemical use restrictions, and your legal obligations when using agricultural chemicals, contact your local DPI Chemical Standards Officer on 136 186 or go to www.dpi.vic.gov.au/agriculture.
For information on weather conditions and inversion layers visit www.bom.gov.au, and for information on chemical use, including phenoxy herbicide.
