INTERNATIONAL
Are High Water Rate Applications Necessary? by Alan McCracken
A high flying Air Tractor avoiding trees during a fungicide application.
A 20 | agairupdate.com
There is confusion in many technical advisors’ minds regarding the need for high volumes of water to obtain good coverage with several still believing this is the only way. In my opinion, many labels tend to be misleading by specifying high volumes that could result in “run-off� and soil contamination. I would like to provoke open thinking that may lead to new ideas for the future. This article has been written to clarify that low volumes do work, although they may not be the answer for all situations. I fully agree that small droplets are more subject to evaporation loss or can be carried upwards by rising thermals causing drift. For this specific reason, all low volume applications must contain oils and adjuvants to obtain consistent results. For low volume spraying to be successful, those involved require a higher level of technical expertise for accurate adjustment and calibration of equipment. Years of trials and experience on many millions
of hectares have proven it is necessary to always add oil and/or adjuvants to the spray solution to obtain consistent good results, especially under conditions of high temperature and low relative humidity. There are numerous oil-type adjuvants on the market with labels that claim to enhance performance and to control evaporation using low dosage rates. Unfortunately, none of these low dose products control evaporation at the labelled rates. The best option is a combination of a vegetable oil with adjuvants to provide a double function with the oil providing protection against evaporation and the adjuvant to reduce surface tension to produce more uniform droplets and enhance coverage. In many areas, growers using high volume applications generally deliver wheat with a significant fusarium level. Growers using low volume spraying in North Dakota and Canada are delivering wheat with practically zero level of fusarium and thereby obtaining a premium price
