Did your spraying do the trick?

If weeds survived, you need to figure out what went wrong so you can avoid a repeat

Field scouting after herbicide application can lead to more successful crop production.

“In the majority of cases, producers will find that the chemicals have done their job” said provincial crop specialist Mark Cutt. “However, in certain situations, field scouting may show the weeds weren’t properly controlled.”

If so, figure out what went wrong.

“A difference in the pattern of weed escapes can indicate poor performance of an herbicide due to environmental conditions, such as temperature, or the possibility of herbicide-resistant weeds being present. If the weeds that escaped the herbicide application are found throughout the entire field, it can point to limited herbicide effectiveness due to environmental conditions. However, if the weeds are found in isolated patches, this may be due to a herbicide resistance issue. If you are unsure of the cause, you should contact an agronomist or chemical company representative to discuss the possible causes of the weed escapes.”

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Scouting after a herbicide application also allows for the assessment of disease development.

“For example, barley leaf diseases such as scald and net blotch move from the older leaves to the newer leaves as the growing season progresses,” said Cutt. “If you find that these leaf diseases are present, you may need a fungicide application once the crop has reached the flag leaf stage.”

Insects can also be evaluated at this time by looking for new insect pests or for increases in insect pests that were present earlier in the growing season.

“Wheat should be monitored regularly for wheat midge during emergence of the wheat head. Cabbage seed pod weevil in canola is monitored by taking sweep net samples. Canola should be scouted when the crop enters the bud stage and as it continues into the flowering stage.”

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