With the summer weed spraying season approaching it is timely to once again look at how best to reduce the risk of spray drift when using chemicals. Given that all chemicals can drift when sprayed, it is essential that management practices be put in place to minimise spray drift.

* Identify risk areas and manage these areas appropriately. It may be necessary in some circumstances to leave an unsprayed buffer to ensure off-target drift does not occur, and then come back and spray the buffer later if appropriate, when conditions have improved.

* Be aware of the weather conditions, taking particular account of wind speed and direction, temperature and humidity and changing conditions throughout the day. Suitable weather for spraying would be consistent light winds (3-15 km/h) blowing away from sensitive areas with mild temperatures and higher humidity.

* Select appropriate chemical products and use according to label directions. The use of certain chemicals can present a significant hazard to neighbouring crops, waterways and desirable vegetation. If sensitive areas are nearby reduce the risk of off-target damage by selecting less hazardous chemicals.

* Spray equipment should be operated with a view to reducing drift. Equipment is available to reduce spray drift, however operator expertise is required to select the right nozzle size and type, spray pressure, spray height and type of equipment to suit the conditions and environment in which the chemical will be sprayed. The two most important factors to consider are droplet size and spray pressure.

* Communicate with neighbours and discuss sensitive areas, chemicals to be used and times of spraying to determine how spray drift can be minimised. This can reduce the likelihood of misunderstanding and future conflicts regarding chemical use.

If 2,4-D herbicides need to be used then be aware that the Australian Pesticides and Veterinary Medicines Authority (APVMA) has placed restrictions on the use of all 2,4-D products. 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. More recently the APVMA introduced additional restrictions on the 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 2,4-D high volatile 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 between 1 May and 31 August when temperatures are lower and relative humidity is higher. 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. The relevant restrictions are now specified on all 2,4-D product labels and are available as a PIRSA Fact Sheet “2,4-D Products - Restrictions on Use” at www.pir.sa.gov.au/ruralchem

AUTHOR: Peter Fulwood, Senior Consultant, Rural Solutions SA

CONTACT: Peter Fulwood, Rural Solutions Nuriootpa Office, Telephone 8568 6400