Trap Catches to August 15, 2025. 

With 17 of 22 sites reporting, aphid numbers were much higher than the last trapping period with the average catch per trap roughly three times that of last week. We also captured Green Peach Aphid at multiple sites across the region (so check individual trap location captures below), from our furthest west to our furthest east locations. Captures of non-vector species increased as well, indicating aphid flights were up overall. The recent flight activity increased the regional cumulative PVY Vector Risk Index, and while levels are still lower than this time last year, they are higher than the 12 year average (see the graphs below).

The capture of green peach aphids after all of the storm events is not surprising; green peach aphids don't overwinter in our region and are brought in on storm fronts from southern areas.  Using the NOAA wind model HYSPLIT (https://www.ready.noaa.gov/HYSPLIT.php) to backtrack wind events in the first week of August did indicate some possible wind events that could possible have brought green peach aphids into our region from more southerly states. Those results are speculative as no ne of the events were directly sampled for aphids...   

The most common aphid was overwhelmingly soybean aphid, the soybean aphid dispersal flights are still ongoing! Small grain aphids, such as corn leaf and English grain aphids remained common, as did buckthorn, potato, and cotton melon aphids. Some others, such as thistle aphid, had decreasing numbers per trap.

Overall, the captures this past trapping period were on track for the 13 year average, but species composition of the vectors means a higher than average PVY Vector Risk Index value. Scouting and active management is highly recommended until fields have been vine killed. Our aphid flights tend to remain high until late August to early September.

 So have a great week and keep scouting!

PVY Vector Risk Index - The ability of an aphid to transmit a virus is referred to as its vector efficiency, these values can be compared across species as a relative efficiency factor (also called the REF). Because data indicate it is the most efficient aphid species in transmitting PVY, green peach aphid's REF is set as 1, with other species' REF being calculated on their comparison to green peach aphid. E.g. soybean aphid has been found to be approximately 10% as efficient at transmitting PVY as is green peach aphid, so soybean aphid is assigned a REF of 0.1.  The PVY Vector Risk Index is a reflection of the comparative ability of the different aphid species to transmit PVY to plants. By multiplying the number of a species caught by its REF, we can estimate the risk from the total vectors captured, adjusted by the ability to transmit virus.

The usual reminders:

- keep 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 can't survive on potatoes, consequently they'll keep moving through the field, sampling additional plants and spreading inoculum in the field. Remember to check predictive sites like this one and University of Wisconsin's weather based Vegetable Disease & Insect Forecasting site,(https://agweather.cals.wisc.edu/vdifn) which uses current weather data and historical populations as a predictor of current aphid vector populations. These will give you a better idea of the potential presence of non-colonizing aphids. 
- 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 usually not effective enough at suppressing PVY transmission, but are still very useful parts of your management program. Treating fields with one of the anti-feeding insecticides (e.g. Sivanto Prime, Sefina, Transform, Fulfill or Beleaf) to control colonizing aphids, such as green peach, potato, or cotton melon aphids, can be beneficial in decreasing movement of PVY inoculum within fields
- aphids preferentially first colonize fields at the edge. Using border crops in the headlands may decrease aphid colonization. But 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.  Also, include those border crops when treating the field for colonizing aphids!

 Happy scouting and have a great weekend!

Click on any image below for larger-scale version.

The average regional PVY Vector capture and PVY Vector Risk Index by week for 2025. 

The regional average aphid vector captures/trap and PVY Vector Risk Index averaged from 2012 to 2023.  The dates are expressed in ISO Week numbers (a standardized method of presenting dates across years). 

Cumulative PVY Risk Index by Site to 8/15/2025

 Cumulative PVY Vector Risk Index by Site to 8/16/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/15/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/15/2025