Trap Catches to September 04, 2026.
Aphid numbers
took another bug drop this week! The average regional aphid capture/trap this
week was ~17.9 aphids/trap compared to ~85.5 aphids/trap last week. The average
PVY Vector Risk values were lower as well. This week's decrease reflects lower
numbers of almost all vector species. While not an exact match, we are following the general 13
year patterns; generally, there’s a decrease in aphid number in early- to mid-September.
When comparing the 13 year average (the top graph) to this year’s data (the
bottom graph), this year’s decrease seem steep (remember to compare the
vertical axis on the two graphs for better perspective). The trap captures from
several sites have not yet arrived, so the population counts may change depending
on those data.
Keep in mind our traps are measuring flying aphids, and while
flight activity may have decreased, aphids may well still persist within fields.
Many of recent aphid outbreaks in commercial production fields have occurred in
late August to early September. So keep scouting and managing fields.
While not an exact match, we are following the general 13
year patterns; generally, there’s a decrease in aphid number in early- to mid-September.
When comparing the 13 year average (the top graph) to this year’s data (the
bottom graph), this year’s decrease seem steep (remember to compare the
vertical axis on the two graphs for better perspective). The trap captures from
several sites have not yet arrived, so the population counts may change depending
on those data.
Keep in mind our traps are measuring flying aphids, and while
flight activity may have decreased, aphids may well still persist within fields.
Many of recent aphid outbreaks in commercial production fields have occurred in
late August to early September. So keep scouting and managing fields.
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 assessment sites (like this one) and check weather-based predictive 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 9/04/2026
For Comparison, Cumulative PVY Risk Index by Site to 9/05/2025 
Aphid Species Capture and PVY Vector Risk Index for the week ending 9/04/2026
Cumulative Aphid Species Capture and PVY Vector Risk Index to 9/04/2026
