2,4-D Products - restrictions on use PDF (190kb)

Background

In 2005, the Australian Pesticides & Veterinary Medicines Authority (APVMA) placed restrictions on the use of all 2,4-D products. More recently, the APVMA also introduced further restrictions on use of 2,4-D high volatile esters, including prohibiting the use of 2,4-D ethyl, butyl and iso-butyl esters between 1 September and 30 April.

The relecant restrictions are now specified on 2,4-D products labels, and it is an offence not to comply with the label instructions. This fact sheet provides information on the label changes as well as an understanding of how the label changes aim to help users manage spray drift.

1. Restrictions: All 2,4-D Products

Some horticulture crops, including grapes and tomatoes, are sensitive to, and can be damaged by, very low concentrations of 2,4-D. To minimise the likelihood of off-target damage the APVMA has placed restrictions on wind speeds and droplet sizes for the use of all 2,4-D products.

Wind speed and droplet sizes

To minimise chemical spray drift, all 2,4-D products in the market must now contain the following label instructions.

• DO NOT use unless wind speed is more than 3 kilometres per hour and less than 15 kilometres per hour as measured at the application site.
• DO NOT apply with smaller than coarse to very coarse spray droplets according to the ASAE S572 definition for standard nozzles.

These label changes are designed to reduce the risk of droplet drift. A consistent light wind of 3-15 km/hr that is blowing away from susceptible crops will help to carry droplets to their intended target. Coarse to very coarse droplets are too large to drift significantly at these wind speeds.

ASAE S572

ASAE S572 is a standard established by the American Society of Agricultural Engineers that classifies the spray from nozzles into spray quality categories according to the droplet size produced. The standard is developed from a similar British Crop Protection Council (BCPC) system, and is based on relative comparisons using internationally agreed nozzles. These descriptive terms for droplet size are more easily understood and practical in use than numerical estimates of droplet size that traditionally have been used to describe droplet spectra. An increasing number of manufacturers of plant protection products now give a recommended spray quality on the label.

The table below gives the approximate Volume Mean Diameter (VMD) for droplets in each Spray Quality Category:

There is a high risk of drift with droplets smaller than approximately 150 μm.

Nozzle types

The only standard flat fan nozzles that will produce coarse spray quality at normal operating pressures are those that have relatively high flow rates (06 size or higher). At normal travel speeds, the spray volume per hectare from these nozzles will be too high to be generally practical for broad-scale farmers.

Low drift nozzles that are 03 size or higher will produce coarse-very coarse spray quality over a relatively wide pressure range.

Air-induction nozzles will all produce coarse, or larger, spray quality over their entire pressure range.

It should be remembered that hydraulic nozzles generally produce a range of droplet sizes.

Nozzles that are defined in a particular spray quality category may still produce a proportion of droplets that are outside these limits.

2,4-D and Volatility

A number of different chemical forms of the phenoxy herbicide 2,4-D are registered in Australia. They include:

• high volatile esters - 2,4-D ethyl ester, butyl ester and iso-butyl ester.

• low volatile esters - 2,4-D ethyl hexyl ester and iso-octyl ester.

• non-volatile forms - 2,4-D dimethylamine, isopropylamine, diethanolamine, triethanolamine and triisopropanolamine.

The volatility of a material is its ability to evaporate and be transported through the air as vapour (gas). The amine forms of 2,4-D are more than 300,000 times less volatile than the ester forms.

Vapour drift of high volatile 2,4-D esters (ethyl, butyl and iso-butyl esters) is increasingly likely when environmental temperatures are high and relative humidity is low. Volatile products can “evaporate” from soil or plant surfaces, up to 48 hours after application, and drift as a vapour possibly for tens of kilometres in conditions favourable to drift. Vapour drift is not visible and can cause damage to sensitive plants some distance from the application site.

The concentration and form of the active 2,4-D constituent is always written on the front panel of the product label.

2. Restrictions: High Volatile Esters

In October 2006, the APVMA introduced additional restrictions on use of 2,4-D high volatile esters in order to minimise the risk of off-target damage to native vegetation and susceptible crops:

The use of high volatile 2,4-D esters (ethyl, butyl and iso-butyl esters) is PROHIBITED between 1 September and 30 April.

Application of 2,4-D high volatile esters must only take place during the spray window between 1 May and 31 August when temperatures are lower and relative humidity is higher. These products should not be sprayed within 1.5km of dormant vines or other susceptible crops to minimise the likelihood of off-target damage. Refer to the “Avoid Spray Drift” leaflet available from PIRSA Rural Chemicals Program: details next page.

Low volatile and non-volatile formulations of 2,4-D can still be used between 1 September and 30 April provided all label directions are observed.

Further information is available from the APVMA website: www.apvma.gov.au/chemrev/24d.shtml

Record keeping requirements

Within 24 hours of completing a spray operation using a high volatile 2,4-D ester (ethyl, butyl or iso-butyl), all users must make and keep a record of the application. The minimum details required in a 2,4-D ester spray record are set out on the following page. If you own or manage land that is sprayed with a high volatile 2,4-D ester product it is recommended and considered good practice that you collect a copy of the 2,4-D ester spray record from any person acting on your behalf (e.g. spray contractor).

A 2,4-D record-keeping form can be obtained from the APVMA website.

For use of 2,4-D high volatile esters between 1 May and 31 August, follow all label directions including:

DO NOT use unless wind speed is more that 3km/hr and less than 15km/hr at the application site.

• DO NOT apply with smaller than Coarse to Very Coarse spray droplets according to ASAE S572 definition for standard nozzles.
• DO make a record of each application within 24 hours of completion (see details below).
• DO maintain a 100m buffer zone between field edges and downwind water bodies and native vegetation.
• DO NOT apply by air.
• DO NOT apply more than 800g ae/ha.
• DO NOT apply in aquatic situations, sugar cane, rights of way or as a harvest aid/ salvage spray.

Minimum record keeping requirements for a 2,4-D high volatile ester application

Training and user awareness programs

There are a number of initiatives by 2,4-D manufacturers, State and Territory departments and the wider chemical industry (Agsafe, ChemCert, SMARTtrain, Spray Solutions) to raise user awareness of how to manage risks when spraying pesticides.

• ChemCert – Ph: 8842 4048.
• SMARTtrain – Ph: 8226 0392.
• Spray Solutions – Ph: 8835 1362.

Further Information:

Contact PIRSA Biosecurity - Rural Chemicals on 08 8226 0528
E-mail: PIRSA.Ruralchemicals@state.sa.gov.au
Website: www.pir.sa.gov.au/biosecuritysa/ruralchem

Australian Pesticides and Veterinary Medicines Authority (APVMA)
Website: www.apvma.gov.au

Agricultural Chemicals – Chemical Resellers, Manufacturers and Private Consultants.

Last update: September, 2007
Author: PIRSA Biosecurity - Rural Chemicals

Disclaimer
Use of the information in this Fact Sheet is at your own risk.  The Department of Primary Industries and Resources and its employees do not warrant or make any representation regarding the use, or results of the use, of the information contained herein in terms of its suitability, correctness, accuracy, reliability, currency or otherwise.  The entire risk of the implementation of the information which has been provided to you is assumed by you.  All liability or responsibility to any person using the information is expressly disclaimed by the Department of Primary Industries and Resources and its employees.