Top Crop Manager

News Diseases Insect Pests
Grasshoppers and armyworms a concern in some areas of Manitoba

July 17, 2023  By Top Crop Manager

Manitoba Agriculture’s most recent crop pest update raises concern over armyworms in some areas of the province. The report does say, however, that first-generation caterpillars are turning to pupae, and some parasitism is being noticed. Some growers are noticing the pupal cases of Cotesia in fields that have armyworms.

Diamondback moth larvae were at higher levels in a few fields in central Manitoba, with a field near Elm Creek needing control.

Grasshoppers also remain a concern in some areas, with some control continuing. Some high populations of pea aphids in peas were found in the central regions in fields in the Notre Dame de Lourdes area, with a couple of fields having insecticides applied. In some fields, peas are nearing the end of their more susceptible growth stages.


The first soybean aphids of the year were reported by an agronomist in the central region July 6, and have since been found in the eastern region, but so far are at low levels.


It was again another week of conditions that do not favour infection by, nor the advance of, pathogenic diseases. A lot can happen before the crop is in the bin, but lack of moisture and associated stresses have been the story so far. Fusarium head blight risk forecasting will likely be wrapped up this week.


Post-emergent scouting continues, and problematic weeds are showing up in crops. Manitoba Agriculuture advises growers to monitor for kochia and pigweeds, as these weeds can be multiple-herbicide resistant. Where weeds do not appear to have been affected by in-crop herbicides, investigate the possible cause and test for herbicide resistance.


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