Prairie water sources, including surface and ground water, can present challenges for farmers applying herbicides.
Particles such as clay and other organic matter are often abundant in prairie water.
Filtration can sometimes improve water quality but even filtered water can limit the efficacy of some pesticides.
The compounds most likely to interfere with pesticide effectiveness are suspended solids such as clay and organic particles, dissolved organic matter, dissolved minerals such as calcium, magnesium, sodium bicarbonate and iron and hydrogen/hydroxide ions (pH).
The use of ground water that is hard and high in salts can severely impair the performance of chemicals. This is often the case with water taken from deep aquifers on the Prairies.
Read Also
Stock dogs show off herding skills at Ag in Motion
Stock dogs draw a crowd at Ag in Motion. Border collies and other herding breeds are well known for the work they do on the farm.
In many cases, water treatments may be less expensive than the crop losses resulting from reduced pesticide efficacy. Many natural surface and ground waters in Western Canada are alkaline, meaning they have a pH level above seven.
Lowering the pH to less than seven may be achieved by adding an acidifier.
Coagulation is another way to improve the quality of rural water.
It is the process of adding chemicals to water to make dissolved and suspended particles bind together. This results in the formation of larger particles that will settle out as sludge.
Coagulation is a safe and effective method of water treatment, commonly used in treating municipal drinking water.
It is also suitable for treating the organic-rich water often found in prairie surface water sources like dugouts, lakes, streams and sloughs.
When using poor water, the concentration of blended pesticides can also affect efficacy. Stronger concentrations of farm chemicals are generally more effective than diluted concentrations.
If water quality is poor, producers should consider reducing water rates, using a higher concentration in the spray tank and applying the chemical mixture at a lower rate per acre.
It has been shown that a reduction of water volume from 100 to 50 litres per hectare can increase efficacy of common farm chemicals such as Assert, Assure, Avenge, Ally, Buctril M, 2,4-D amine, MCPA amine, 2,4-D + Banvel, Hoegrass, Excel, Mataven, Fusilade, Roundup, Rustler, Poast, Glean, Amber, Select and Torch.
Of the chemicals tested, only Achieve had a lower efficacy when low water application rates were used.
All herbicides used in Canada are registered by the Pest Management Regulatory Agency at rates that provide a reduction in weed biomass of 80 percent or more.
Unique conditions
The PMRA considers many factors when testing chemicals, including water quality and water volume.
The end goal is to predict the effect of non-optimum application conditions such as poor quality water and inclement weather conditions and to arrive at an application rate that the manufacturer believes will be most effective under a wide range of conditions.
This system of testing works well but extreme water quality conditions experienced in some prairie regions may not be fully anticipated.
That means there may be a considerable opportunity to increase the efficacy of pesticides used in the Prairies by conducting water tests specific to individual farms.
Commercial and provincial laboratories can analyze the composition of rural water sources to ensure that water is suitable for chemical application and to devise strategies to improve water quality.
Limited work has been done to determine the negative effects of naturally poor water quality on pesticide efficacy.
This lack of research is particularly relevant in Western Canada where large quantities of agricultural pesticides are used.
However, if water quality and blend concentration are both optimized, it is likely that pesticide efficacy could be increased significantly.
