Dry conditions on the western Prairies and wetter conditions in eastern prairie regions may cause problems for farmers who spray herbicides.
The wind is the culprit in drier areas, where more silt and organic matter are either blown into the water or stirred up from the bottom.
As well, less spring runoff means that spring-fed dugouts have higher concentrations of minerals. The water should be tested for hardness.
In wetter areas, such as southeastern Saskatchewan and southern Manitoba, heavy runoff and flooding has stirred up silt and organic matter.
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This silty water can reduce the effectiveness of the herbicides glyphosate, paraquat and diquat. Proper water filtration is vital if these products are to be effective.
“Dugout water generally is the best source for agricultural spraying, as it generally contains few minerals that might interfere with spray formulations,” said Rick Holm of the University of Saskatchewan’s Crop Development Centre.
But many dugouts are dry in the western Prairies this year and farmers might have to use hard well water.
If so, they can add 21-0-0-24 ammonium sulfate fertilizer to the water so that it can be used with glyphosate. At a rate of three kilograms per 100 litres, the fertilizer softens the water and helps the herbicide dissolve thoroughly in the sprayer tank.
Ken Kirkland, a scientist and agricultural consultant in Vermilion, Alta., said there is another strategy for farmers who only have access to hard water and can’t add fertilizer.
“Increase the concentration of glyphosate in the mix,” he said.
By reducing the water volume, less glyphosate acid is tied up by hard water ions, he added.
Water with higher concentrations of magnesium or calcium can impair the effectiveness of 2,4-D. These minerals are usually found in well water.
A 2,4-D ester, LV, formulation should be used if hard water is the only option. Using less water in the mix might also help. Approved, non-ionic surfactants may also help with hard water problems.
Bicarbonate can also reduce the effectiveness of 2,4-D, especially when applied at lower rates. It is usually found in water from wells 100 metres or deeper.
LV ester formulations may help, but farmers can also switch to MCPA amine or ester if it controls the target weeds. Increasing the rate of 2,4-D may improve performance. Non-ionic surfactants at a rate of one litre per 1,000 litres of spray can also help when using the amine version of 2,4-D.
Grass killers are less affected by water quality, but some, such as Achieve, Poast and Select can be less effective if bicarbonate is in the water supply.
Research has found that bicarbonate problems can be overcome using liquid ammonium sulfate fertilizer at 1.6 litres per acre or 0.8 kilograms of 21-0-0-24 dry ammonium sulfate fertilizer per acre. Farmers can also use 0.2 litres per acre of 28-0-0 liquid nitrogen fertilizer as an adjuvant.
Herbicides work best on actively growing weeds. They may be less effective in dry soils where weeds are growing poorly.
Herbicides may not be able to penetrate dust-covered weed leaves in dry fields.
Drought and poor prices might also cause producers to make bad decisions.
“The problem comes when producers are facing tough times,” Holm said.
“They sometimes cut rates in hope of saving some money. Instead they get a wreck.”
