Fusarium head blight risk for wheat is moderate to low in different areas of Manitoba. Most of the wheat crops have finished flowering and thus at low risk. By end of the month, Fusarium head blight risk maps may not be needed.
Grasshoppers continue to be a concern in some fields.
Canola growers should be checking canola for Lygus bugs. Lygus can potentially be of concern when they feed on the pods of canola if levels are high, although feeding to flowering crops is not likely to be economical as canola has a very good ability to compensate for damage to flowers, especially when soil moisture is good. So far Lygus levels appear to be below economic levels in canola, with a few exceptions in the Eastern part of Manitoba.
Note: For those monitoring traps for bertha armyworm, the traps can be removed after you do your counts this week. We have enough weeks of data to know what the regional risks are. Overall trap counts in Manitoba were quite low this year. A map of the cumulative counts, as of July 28th, is posted in the update, and risk maps are also posted at the following MAFRD website (the July 28th map will be posted tomorrow): http://www.gov.mb.ca/agriculture/crops/insects/bertha-armyworm-forecast.html
Submitted by: John Gavloski, Entomologist & Vikram Bisht, Pathologist, MAFRD
When does the canola become more resistant to flea beetles?
Estimating % defoliation. Estimating % defoliation can be tricky, as our eyes are drawn to the damage and it is easy to overestimate how much feeding has occurred. Having a photo key as a guide can be useful for learning to assess defoliation levels.
Cutworm Feeding. High levels of feeding by cutworms has been noted in sunflowers in the Carman and Sanford areas, and in corn in the Starbuck area.
Insecticide application tips for cutworms.
Insect Monitoring Programs:
Diamondback moth: Diamondback moth counts have increased in some locations in eastern Manitoba and the Swan River Valley.
Bertha armyworm: The map provided in the report indicates at what stage the pupae of the bertha armyworm are in their development. Currently, some may have accumulated enough heat to be about 60-75% through their pupal development.
Submitted by: John Gavloski, Entomologist & Vikram Bisht, Field Crops Pathologist, MAFRD
Prepared by John Gavloski, MAFRI Crop Entomologist
Trap counts for adults of bertha armyworm have generally been lower over the past couple of weeks. So populations of the moth stage have peaked and fewer moths are now present. Egg laying should be nearly complete. Some traps had cumulative counts in the uncertain risk category (300-900 moths), and traps near Elm Creek, Sperling, Ridgeville and north of Roblin have counts in the moderate risk category (900 – 1,200 moths).
A table showing data from the bertha armyworm monitoring program can be viewed on the MAFRI website at:
When currently scouting canola fields, look for larvae of bertha armyworm. So far only low levels of larvae have been noticed. Many larvae will still be small and harder to notice. Also note that populations of bertha armyworm can vary greatly between fields within a region, so assumptions regarding a field cannot be made based on findings in nearby fields.