A confirmed case of wheat streak mosaic in south-central Manitoba, diamondback moth rising in the east and concern over thresholds for soybean aphids are covered in the province’s latest insect and disease update.
Attached here are the PDF of the Aug. 3 update from provincial entomologist John Gavloski and an XLS file documenting the latest bertha armyworm trap counts in the province.
Due to a publication ban imposed on most provincial communiques ahead of the Oct. 4 provincial election, these updates will not be posted this summer on the Manitoba Agriculture, Food and Rural Initiatives website.
The report notes a confirmed case of wheat streak mosaic virus near La Riviere, about 45 km west of Morden.
Levels of diamondback moth continue to be high, particularly in the Beausejour area, although some high populations have also been reported recently in the Niverville and Dugald area, the northern region of the Swan River valley, and the northern Interlake, the province said.
Soybean aphid levels have been increasing in central Manitoba, where some confusion remains over when it’s economical to control soybean aphids.
The economic threshold — that is, where control is advised to prevent economic damage — is not 250 aphids per plant, the province noted. The economic threshold is when there are on average at least 250 aphids per plant, and the population is increasing,
Recent data from the province’s bertha armyworm traps is updated and current on the Excel spreadsheet, but has not been updated on the MAFRI website due to the publication ban.
“We are now finished with the adult monitoring of bertha armyworms, so these traps can now be removed,” Gavloski noted in an email.