26 September, 2018
Spring has sprung with some cotton in Central Queensland already out of the ground and planting beginning around Goondiwindi and Moree, which is likely to gain momentum across the various regions throughout the next few months. The season to date suggests the crop will be back on area compared to last season, however there will be irrigated crops in all regions and the dryland crop area will be determined by future rainfall events.
With this in mind, future rainfall events are likely to trigger fallow spraying of which broadleaf weeds will be part of the weed spectrum, often a phenoxy herbicide such as 2,4-D is an appropriate choice and/or mixing partner. This group of herbicides are a valuable tool to all growers at this time of year yet can cause severe damage to susceptible crops if used incorrectly.
As a consequence, awareness of the use and application of 2,4-D herbicides becomes heightened through the months of October to April, coinciding with increased risk of drift events that may affect native vegetation and/or sensitive crops such as cotton. This we all know well, but what is topical of late are recent developments regarding the ongoing Australian Pesticide & Veterinary Medicines Authority (APVMA) review of 2,4-D.
Due to incidents of reported spray drift over the years and more recently with “significant incidents in the last two summer spray seasons” reported, the APVMA have concluded, after consultation with many stakeholders that an update is necessary for new label instructions. At the time of writing it is important to note that this is a proposed draft to label instructions. The APVMA position reads that the “currently approved 2,4-D labels do not provide adequate instructions to effectively mitigate risk associated with spray drift”.
Proposed changes to the label via this draft relates primarily to record keeping, application techniques that require observance of mandatory no-spray buffer zones and advice on spray quality and timing. Additional instructions are proposed to ensure users are not applying these products under conditions that are conducive to temperature inversions (inversion drift), and an increased spray quality requirement of VERY COARSE is proposed to mitigate the potential for physical droplet drift.
Of particular note is an advisory statement for use in cereals, fallows and pasture for 1st October to 15th April which suggests the use of EXTREMELY COARSE (XC) to ULTRA COARSE (UC) droplets, likely requiring higher water volumes/ha, lower operating speeds and boom heights – these combined are considered to “mitigate off target inversion drift” and that “EXTREMELY COARSE droplets will produce <3% driftable droplets”. There appears to be no indication that there is any change or restriction to currently approved use patterns.
It is important to reiterate that at the time of writing these instructions are in a draft form so may be subject to change and will be more clear in October when the formal label instructions come into effect. It is important that all growers use CottonMap (www.cottonmap.com.au) and advise neighbours of sensitive crops and their location via a farm map.
It is in the interest of all growers to ensure that these products remain a viable choice for use in the farming system. The review into 2,4-D is due for completion in 2019 – perhaps these label changes may contribute to a season of minimal impact from drift events?
By Chris Teague – Extension & Development Agronomist, Border Rivers & Balonne.
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