Compiled by:
John Gavloski, Entomologist, Manitoba Agriculture, Food and Rural
Initiatives, Crops Knowledge Centre,
Phone: 204-745-5668; Fax: 204-745-5690
To report observations of insect activity or control that may be of interest or importance to others in Manitoba, please send messages to the above contact addresses.
To be placed on an e-mail list so that you will be notified immediately when new Manitoba Insect Updates are posted, please contact John Gavloski at the address or numbers listed above.
Aphid levels are high in some cereal fields in Eastern and Central Manitoba. Lygus bugs are numerous in some sunflower fields.
Aphids in cereals: High population of aphids
continue to be noticed on cereal crops in the eastern
and central regions of Manitoba. The economic threshold
for aphids in cereal crops is 12-15 per stem prior to
the soft dough stage. Once cereal crops reach the soft
dough stage aphid control is no longer likely to be
economical.
Root Maggots in Canola: Although populations of
many potential pests of canola have been low this
summer, there are some areas where root maggots, and
evidence of their feeding, are quite common. In the area
around Carman it is quite easy to find root maggots or
there feeding damage. In many of these fields, however,
it is not obvious that the feeding has occurred unless
plants are pulled to look at the roots, because
otherwise the plants are still growing well. Moderate to
high levels of root maggot feeding have also been
reported from fields near Snowflake and Foxwarren.
Update on insects in sunflowers: As sunflowers get
into the late bud stage and start to flower, it is
important to scout for insects that potentially feed on
the seeds. This is particularly important in confection
sunflowers. So far we have not seen or heard of any high
populations of seed weevils in Manitoba. Banded
sunflower moth adults are showing up in pheromone-baited
traps, but economical populations are not being
reported. Populations of plant bugs, including lygus
bugs are high in some fields. Aside from lygus bugs,
there is a black species of plant bug that is more
numerous than lygus bugs in many fields. We are not
quite sure what this plant bug species is yet, but are
working on having it identified. Many plant bug nymphs
(several per head) are being found in a lot of sunflower
fields. Not all look like lygus bug nymphs, but we are
currently not sure what the nymphs from the black
species of plant bug look like, which complicates
scouting even further. When scouting sunflowers, make
sure to have a good look for plant bugs. The economic
injury level for lygus bugs in confection sunflowers is
about 1 lygus bug per 9 heads. Lygus bugs are not likely
to be economical in oilseed sunflowers.
Lygus bugs in sunflowers: Control of lygus bugs in sunflowers has been added to the label for Matador (PCP# - 24984). Application can be by ground or air. Matador is the first, and currently only, product to be registered in Canada for control of lygus bugs in sunflowers.
Bertha Armyworm Forecasting: Monitoring for bertha
armyworm adults is complete. Remaining traps can be removed from
the field. No traps exceeded 300 moths per trap over the
trapping period. So all fields rated as low risk of damage from
larvae. Highest cumulative counts were from the South Parkland
region; Hamiota (292), Russell (274), Elkhorn (262), Miniota
(250), and Shoal Lake (246). Based on this, we are not expecting
it to be a bad year for bertha armyworm. Data can be viewed at:
https://www.gov.mb.ca/agriculture/crops/insects/bertha/index.html
Grasshopper Survey: A reminder for farm production
advisors and those wanting to participate in the annual
grasshopper survey that counts are done during August, when the
majority of grasshoppers are in the adult stage. This year
grasshopper development is later than normal, so in some areas
counts may have to be delayed until adult grasshoppers are
prevalent. The grasshopper survey protocol is located at:
https://www.gov.mb.ca/agriculture/crops/insects/fad95s00.html