| | Before venturing off into the new world of spraying multiple products, producers should ensure that any mix they use does what it is supposed to do, and is actually needed.
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"With the movement toward reduced or zero-tillage, the sprayer has taken on added significance on many farms," says Doon Pauly, crop specialist, Ag-Info Centre, Stettler. "As more and more land receives multiple spray passes per year, farm managers are now seeking ways to improve the efficiencies of their sprayers by combining diverse products in the spray tank to eliminate a spraying operation. These new combinations include herbicide-fertilizer, herbicide-insecticide, and herbicide-fungicide mixes. Although this strategy may reduce spray passes, it may not increase efficiencies if the applied products aren't necessary."
Pauly says to first make sure the solution is a registered mix. To be registered for use in Canada, the efficacy of a crop protection product and all its registered mixes needs to be supported by research. Product and tank-mix registration gives the user some level of confidence that the product will perform up to certain expectations.
"Unfortunately there are few registered fertilizer-pesticide mixes and it usually is a 'buyer beware' situation, even if the fertilizer salespeople claim it won't form a sludge or gel in the spray tank," says Pauly. "It doesn't make much sense to save a $7/ac spray operation and ruin a $20/ac herbicide by mixing it with a fertilizer that reduces product effectiveness."
Some herbicide-insecticide and herbicide-fungicides combinations are registered so users have some level of assurance that these will work properly.
"But before using one of these registered mixes, try to determine if the added cost of an additional product is really necessary by answering a few questions," says Pauly. "For instance, is the targeted pest present? Is the crop stage right for the pest to reduce yield? Is the pest level above the economic threshold so control is justified? There is a real temptation to add an inexpensive crop protection product to a spray mix 'just in case' the pest may be present, or 'just in case' the observed low levels might become problematic in the future."
Sprays applied without considering the actual severity of the pest, or staging of the crop, are often ineffective and may even be detrimental. An improperly timed insecticide application may also kill beneficial insects and prolong existing pest problems or induce new ones.
"There is also growing evidence that low levels of some pests are actually beneficial and may contribute to good yields," says Pauly. "A 'just in case' spray mix may be an unnecessary input cost and may even do more harm than good."
If a mix is applied early in the season, another pass may still be needed at the more traditional time of pest control. This applies primarily to herbicide-fungicide tank mixes for early season control of leaf diseases in cereal crops, but can apply to other situations as well. "For cereal crops, the flag leaf and second last leaf are essential for proper kernel development and grain filling, so fungicides should protect these structures," says Pauly. "An early season fungicide-herbicide application will control diseases at the time of spraying, but offers little protection for the important leaves that have not yet developed. Cereal leaf diseases need to be controlled at the flag leaf stage if the disease is present and conditions favour disease progression, even if there was an earlier fungicide-herbicide application."
Contact:
Doon Pauly
403-742-7928 |
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