Trap Catches to August 21, 2026.

Another big jump in aphid vector numbers this week, driven mostly by a large and widespread flight of soybean aphids. The total number of vector species of aphids captured across all locations almost doubled, jumping to 1875 from last week's 983, the largest portion of which was comprised of 1158 soybean aphids. Average trap captures 47.8 vectors/trap to 93.8 vectors/trap; the average trap capture of soybean aphids more than tripled (rising to 77 soybean aphids/ trap from last week's 21.8/trap). The average PVY Vector Risk Index rose this week from 7.4/location to 11.3/location; the increase in PVY Vector Risk Index at individual locations was highly variable. Our regional aphid numbers and PVY Vector Risk Index values are now approximately 3 times those of our 2013-2025 averages. While we may have started the season a bit more slowly, 2026 has developed into a high PVY vector year.

Green peach aphid numbers are higher this week, with GPA being recovered at 3 new locations. Cereal aphid numbers are continuing to rise. In fact, the numbers of most of the vector species recovered in most traps increased this week. While we tend to focus on the green peach aphid, it isn’t always the species driving the risk of PVY transmission.  At this time, the high number and wide distribution of other vector species (especially soybean aphid) over the past two weeks is having the greatest impact on the risk of PVY transmission

 Our rapid increase in aphid numbers may be the result of our temperatures dropping back to a level more conducive to aphid reproduction in combination with the localized lack of precipitation in many areas in MN & ND. The decrease in average daily temperature certainly would have increased aphid reproductive rates. And the lack of precipitation may have significantly decreased the amount of mortality from fungal pathogens, an important factor limiting aphid populations in most years.

Bottom line is, we’re not out of the woods yet. The appearance of green peach aphid and the continuing numbers of potato aphid also mean that table and processing fields are at risk as well. Scouting is definitely recommended. Also, for seed fields that have not vie killed, appropriate management should be continued.

The usual reminders:

- vector flights are getting heavy, so continue scouting; aphids can establish early after potatoes are up. Field scouting is less effective at finding aphid vector species that don't colonize potatoes. While these species will enter potato fields and probe plants, they cannot survive on potatoes. Consequently, they'll keep moving through the field, sampling more plants and potentially moving inoculum already in the field to uninfected plants. Consult risk assesment sites (like this one) and check weather-based predicitve models like University of Wisconsin's Vegetable Disease & Insect Forecasting site (https://agweather.cals.wisc.edu/vdifn).

- the research literature reports that the use of crop oils is the most consistent post-planting technique in preventing transmission of PVY and it can be improved with the addition of the insecticide Lambda-Cyhalothrin.

- most of the research indicates that insecticides on their own are not effective enough at suppressing PVY transmission, but are still useful parts of your management program. Treating fields with one of the anti-feeding insecticides such as Sivanto Prime, Sefina or Transform to control colonizing aphids, such as green peach, potato, or cotton melon aphids, can be beneficial

- if using a border crop, it's a good idea to use treated seed to prevent the development of potential vector species in that border and to include the border plants when applying foliar insecticides in the field.

Have a great week and keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Risk Index by Site to 8/14/2026

For Comparison, Cumulative PVY Risk Index by Site to 8/15/2025 

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/14/2026

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/14/2026