Trap Catches to July 31, 2026.

Aphid numbers took a huge jump in the past week. Aphid counts are up across the region with grain aphids leaving maturing wheat fields and soybean aphids starting their late July/early August dispersal flights. Regional PVY Vector Risk Index values have jumped with the populations and are now higher than at this point last year.  The increase occurred across the  trapping network with average captures per trap increasing at almost all locations reporting this week. This has resulted in an increase in average PVY Vector risk at all locations.   

We saw an increase in almost all vector species. The numbers of the 3 small grain aphid vectors most common to our area (bird-cherry oat, corn leaf and English grain aphids) increased at almost all trap locations. Other vector species such as cotton-melon and buckthorn aphids also saw a significant increase. Soybean aphids were by far the most numerous species at all locations, with some sites suffering very large flights this past week. Large soybean aphid flights are not unusual in MN and ND in late July and early August and are sometimes part of our late season PVY epidemiology. 

With much higher numbers of vectors present this week remember to scout and use appropriate management tactics.

 The usual reminders:

- vector flights have started, 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 7/31/2026

For Comparison, Cumulative PVY Risk Index by Site to 8/01/2025 

Aphid Species Capture and PVY Vector Risk Index for the week ending 7/31/2026

Cumulative Aphid Species Capture and PVY Vector Risk Index to 7/31/2026

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