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Drift or spray tank contamination?
By Hugh Martin - Weed Management Specialist, Guelph

The spring season is almost over. Time to finish up the spraying and to clean up the equipment. One of the things we have found with sprayers during the last few years is an increase in herbicide injury due to poor sprayer cleanout.

At this time of year it is not uncommon to notice a field of beans or another of the sensitive crops that are showing some signs that they got a mild dose of the wrong herbicide. We usually lift our eyes first to the horizon to see what the neighbours have been doing. If we are on the edge of the field, yes that is possible. Dicamba is well known to go pay the neighbours a visit. Glyphosate will also drift a short distance and then show up on wheat, corn, tomatoes etc. We have also seen cases of a product like Reflex drifting onto apples. Essentially any product can drift if the conditions are right.

When assessing herbicide injury look to see if the drift is mostly on the edges or across the field? Is it the same across several tankfuls? Is it worse where you started with the first sprayer load? Look for patterns that are clues to the source. Talk to whoever drove the sprayer and get more details.

The problem sometimes is that 28 per cent or surfactants such as Agral 90 clean out residues from the last job that plain water misses. As a result we carry residues from the last spray job into the next field and it can contaminate a whole tank and cause injury over the whole field.

Some of the newer herbicides are more difficult to cleanout of the spray tank and you need to do more than just a quick rinse and go. Many products have instructions on the label and may suggest a detergent, ammonia, or one of the tank cleaning products on the market. Actually, 28 per cent or Agral 90 do make good tank cleaning agents.

The cleaning procedure is generally to:

3 drain the tank

3 fill with water and detergent or tank cleaner, flush the booms and hoses and allow the sprayer to stand full of cleaning solution for several hours if possible then drain and flush;

3 inspect inside for residues and repeat step 2;

3 remove the nozzles and screens and wash them separately;

3 wash the outside of the tank.

Most spray drift and tank contamination injury is mostly cosmetic but it can be very serious and damaging to yields and it certainly does not help your friendships with your neighbours.

Enjoy the weather and work safe. Your family needs you.

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