Alfalfa weevils at high levels, more stripe rust detected

Manitoba Insect & Disease Update for June 21

Alfalfa weevil has been reported at high levels in fields in the Interlake, Southwest, and Northwest. There are some lingering cutworm issues in the northwest, although populations of cutworm in many locations are turning to pupae.

Stripe rust has been detected in more locations around Manitoba. The disease is known to have overwintered in Manitoba near Austin. Reports have come in of detections of stripe rust in winter wheat near Neepawa and near Winkler. Levels have been low overall and are not a major concern at this time. There is a researcher in Lethbridge who is interested in obtaining stripe rust isolates from Manitoba, so if you do detect stripe rust in your field please contact Holly Derksen for information on how to send the samples to Alberta for research purposes.

Got cereal leaf beetles? Donate some to science

Low levels of cereal leaf beetle have also been found in some fields. A parasitic wasp called Tetrastichus julis, which is specific to cereal leaf beetle, has been released in Manitoba in the past few years. It seems to be establishing well, and hopefully will keep populations at sub-economic levels. We are hoping to once again collect cereal leaf beetle larvae and determine the percent of larvae that are parasitized from fields in various regions. So if you are noticing any cereal leaf beetle larvae on wheat, oats, barley, or any other cereal crop, please collect a sample or let me know so we can collect some and determine the level of parasitism in the population. Areas that may have low levels of parasitism would be considered for possible future releases of the parasitoid. Ideally a sample of at least 25 larvae is good for estimating percent parasitism, but larger samples (50 to 100 larvae) are even better. They can be collected off the plant or in a sweep net. Place some food for them in the container as well.

Contact John Gavloski (see contact information further down) to have someone collect a sample from your field. We do not have records of cereal leaf beetle east of Carman, so if noticed in more eastern areas of the province, please let us know so we can verify can collect a sample.

Note that although larvae of cereal leaf beetle are yellow with a brown head, they may look like drops of oil on the leaf, because they have a fecal coat.

Agronomists, Farmers, Farm Production Extension Specialists, Extension coordinators, and others scouting crops: Please remember to send in reports of insects or plant diseases over the growing season so we can make these updates as complete as possible, and alert farmers and agronomists where and to what degree insects and pathogens are of concern or being controlled. Information can be sent to: John Gavloski (entomologist) at [email protected] (phone: 204-750-0594) or Holly Derksen (plant pathologist) at [email protected] (phone: 204-750-4248).

Click here to view the full Manitoba Insect & Disease Update on the Manitoba Agriculture website.

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