John farms 1,500 acres in east-central Alberta. Last June, he wasn’t sure why weeds were popping up in his chemfallow. His only theories were a possible problem with his application rate or a bad batch of chemical. His cereal crops were doing fine. So why was he getting spotty weed control in his chemfallow?
I visited his farm two weeks after he’d sprayed. When I arrived we thoroughly inspected his field. Sure enough, his weed control was hit and miss. Where one plant thrived, only inches away another was dead. There seemed to be no pattern.
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I had many possible sources of the problem to consider — equipment failure, product failure, weather conditions, field condition prior to application, application rates, or water source.
Since the correct amounts of water and chemical had been applied and trash was minimal, I concluded the field condition prior to application of product was not a factor. Also, the weather was not the problem. There had been no wind or frost, and temperatures were reported above 15 C.
John’s cereal crops showed good weed control, so equipment failure could be ruled out. When I checked, there were no complaints about the chemical lot from other producers, so the product wasn’t the problem either.
My last concern was the water source. John seemed doubtful this was the problem. He’d been using the same water source for years without any trouble. But to be certain, I tested John’s water.
The results were surprising. John’s water source tested extremely hard with over 1,100 mg/l of calcium carbonate. In this case, there is an association between poor weed control and hard water. In order for John’s product to control weeds his water needed to be treated to soften it. Glyphosate products work better with softer water.
For John’s next pass on the chemfallow he treated his water with conditioner and then added the product he wanted to use. Soon after, John saw results and his weeds were gone. Softening his water source had fixed his problem. John felt this was an excellent ending to his story and he continues to have good success with that field.
A simple test for hard water is all that was required to recover John’s field. Some products require certain water quality. Know your own water quality and how it affects certain products in order for weed control to meet your expectations.
Marie Cowan is an assistant plant manager for Richardson International in Oyen, Alta.
