Two spray application workshops, titled “Don’t be a Drifter”, were held in Renmark and Mildura on the 23 rd and 25 th November respectively. The course presenters were Craig Day and James Wright. Craig is a broad acre spray contractor and chemical use trainer in all aspects of herbicide application. James runs Wright Viticulture, which is a consultancy business, and also develops specialist training and technical advice for the viticulture industry, which includes assessment of canopy coverage. A number of topics were covered during the course, which included: • Discussion on chemistries of almond chemicals, i.e. mode of action and relating it back to the application decisions that should be taken Set-up, use & calibration of boom sprays (under-tree spraying) including spray speed & height Set-up, use & calibration of air-blast sprayers (tree spraying) A demonstration using fluorescent tracers and UV light to observe chemical coverage on the weeds and trees using different nozzles, pressures, water rates, speeds, etc Label changes in relation to droplet size, drift and buffer zones Water quality, importance of adjuvants and understanding target complexities Time of application, weather conditions including consideration of Delta T – speed, direction, temperature, inversion Buffers and chemical sensitive areas – new APVMA requirements Spray quality/droplet size requirements for different products and targets Selecting the correct spray nozzle and pressure, setting up rate controllers • • • • • Drift – vapour and particle • • • • Understanding spray application information on chemical labels Chemical handling systems and personal clothing protection • Both days were well attended with keen interest about the above topics. The information presented aimed to encourage attendees to review their application methods and modify them when greater efficiencies could be achieved. A number of key points were raised during the workshops and are summarised below: • Review chemical labels which now recommend specific water rates and nozzle selection; particularly for herbicide use e.g. Glyphosate labels recommend • • • Water rates and mixing order • Storage and handling
a nozzle producing coarse droplets and water rates of 80 to less than 200L/Ha. • Discussion of mode of action of chemicals that are surface acting, translaminar or systemic and the importance of water rates and coverage for each mode of action e.g. Glyphosate has a systemic mode of action and therefore works best if there is a higher concentration of chemical per water droplet and may only need water rates less than 150L/Ha. • Highlight the main causes of drift in relation to inversion layers and small droplet size. Droplet sizes less than 150 micron are prone to drift and off target damage. Air induction nozzles help provide a coarse droplet which will help reduce drift.
Dry Flowable Granules, Suspension Concentrates, Emulsifiable Concentrates, Water Soluble Concentrates and finally Adjuvants / Wetters. If not mixed in this order, settling of chemicals can occur in the tank or the activity of the chemical will be reduced. • How to review individual nozzle and boom section pressure was examined. It is best to set pressures at the nozzle using a pressure gauge rather than relying on the pressure gauge at the pump. While doing this, double check for pressure variations between the booms as individual booms are shut on or off and adjust accordingly. • A review of chemical sheds and personal protective equipment was also carried out. Remember to keeps MSDS sheets up
to date and no older than 5 years. The more you keep PPE hygienic (clean) and readily accessible, the more likely it is to be used by spray operators. • The test of spray coverage with dyes and UV lights showed that air induction nozzles can help reduce drift while not having a detrimental effect on coverage. Pressure could also be adjusted to help enhance coverage. VERY IMPORTANT: Good canopy coverage is dependent on a number of factors including: wind velocity and volume of displacement, nozzle selection, pressure and corresponding droplet size, rates of water applied and ground speed. Before attempting
any major changes to canopy sprayers, check for adequate coverage (preferably doing a dye test with UV lights) before and after changes. Don’t put yourself in a position of poor canopy coverage in a year of high disease pressure! The feedback received about the courses has been very positive with most attendees planning to use some of the information learnt to make changes on their own property. Future Don’t be a Drifter spray workshops will be planned for regions not covered by the initial two courses. For more information on the recent spray workshops or registering interest for future spray workshops, contact the ABA office. For further information contact: Brett Rosenzweig Industry Development Officer Almond Board of Australia P 08 8582 2055 or 0429 837 137 E: email@example.com
• The use of Delta T to predict the longevity of spray droplets in an off target situation. It is indicative of evaporation rate and droplet lifetime. Delta T is calculated by subtracting the wet bulb temperature from the dry bulb temperature. Droplets in a situation where the Delta T is less than 2 may persist for longer than is intended and therefore be at risk of causing off target drift and damage. Conditions with a Delta T of 8 or greater may mean the droplet dries too quickly and absorption rate into the target plant may be reduced or not even reach the target at all. • The importance of understanding and measuring water quality i.e. water hardness, high pH and high water turbidity. Glyphosate’s effectiveness and longevity in the tank will be reduced by high water hardness and / or pH. Adjuvants may need to be added to improve water quality. • The correct mixing order of water conditioners and herbicides. Tank mixes should be in the order of Water Conditioners, Wettable Powders,