Trap Catches to August 01, 2025.

What a difference a week makes, again.... With 20 of 22 trapping locations reporting, total aphid vector captures were approximately 3 times that of last week.  This puts our cumulative seasonal capture about 1 week behind the 13 year regional average (see the graph below) and behind last year's population counts (see the maps below). 

Soybean aphid numbers went by 5, English grain aphids tripled, cotton melon aphid numbers doubled and non-vector species tripled as well. In the past week conditions for aphid population growth have been good, alternate host crops (especially small grains) have started to be harvested, and the lack of rainfall facilitated aphid dispersal. These are all conditions that occur about this time of year. And all contribute to the increased aphid vector activity we experience at this point in the late season.     

The regional weather outlook over the next week will likely cause a similar increase in aphid flights. Small grain harvest has commenced and small grain aphids are increasing their flight activity. Soybean aphid flights have started to ramp up, generally resulting in increasing visits to seed potato fields.  Like soybean aphid, other non-colonizing aphid species will be increasingly entering seed fields and, while they don't feed or reproduce on potatoes, will probe and transfer inoculum while they're visiting. The populations of several aphid species colonizing potatoes have increased so scouting is increasingly important at this point. Given the weather, their populations will be increasing and control of growing colonies may be required.   
So, keep scouting and checking the predictive sites!

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 (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 8/01/2025

 Cumulative PVY Vector Risk Index by Site to 8/02/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/01/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/01/2025

 Trap Catches to July 25, 2025.

With 17 traps reporting this week the number of aphids recovered in traps this week were approximately the same as last week. However, the PVY Vector Risk Index increase was not as large (reflecting a greater proportion of less efficient vector species in the catch this week - see our section on the PVY Vector Risk Index below). Recent rain events in various parts of the region may also have suppressed aphid flights. 

Soybean aphid numbers are up this week, perhaps signaling the onset of what Bruce Potter (an outstanding IPM researcher) coined as The Sturgis Dispersal Event. We frequently experience a wide scale dispersal flight of soybean aphids within a couple of weeks of the start of the Sturgis motorcycle rally. Cotton melon aphid numbers were up this week, and both small grain aphids and potato aphids remain active.  

The drier, but still warm, weather expected next week may increase aphid flights. As small grains continue to dry and harvest increases, look for increased numbers of small grain aphids moving to alternate crops to finish their season. We tend to have our biggest aphid flights in early August, and while this week's capture was behind the 13 year average, our PVY Vector Risk Index values remain on that average track.

So, keep scouting and checking the predictive sites!

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 (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 7/25/2025

 Cumulative PVY Vector Risk Index by Site to 7/26/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 7/25/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 7/25/2025

 

Trap Catches July 18, 2025.

With 19 traps reporting this week the number of aphids recovered in traps this week increased ~20% this week, but the number of vector species was basically the same. The general pattern of population increase and PVY Vector Risk Index values are close to the rates seen in our 13 year average. Our vector species captures are slightly lower than the 13 year average, but our PVY Vector Risk Index values are roughly 3 times higher than our average numbers. Our trapping history suggests populations may increase at a steady rate for the next 4 weeks (see the graph on average regional weekly vector captures below). In any case, this would lead to high seasonal levels of PVY Vector Risk.

This week we saw an increase in aphid species hosted by small grains. Small grain crops are increasingly maturing and will have lowered nutritive value to aphids so winged forms are developing and moving to less mature crops to build new colonies. Our numbers of both corn leaf and English grain aphids more than doubled over last week. Buckthorn and Damson-hop aphids remain well represented in trap captures this week and cotton-melon and potato aphids were recovered at several locations. No green peach aphids were recovered this week. 

 Keep scouting and checking predictive sites. 

The usual reminder:
- 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. And to include those border crops when treating the field for colonizing aphids.
 Happy scouting and have a great weekend!

Click on any image below for full-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 7/18/2025

 Cumulative PVY Vector Risk Index by Site to 7/19/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 7/18/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 7/18/2025

 

Trap Catches July 11, 2025.

The number of aphid species capture in the traps doubled over last week, with a much greater percentage being vector species.  With 19 traps reporting, traps recovered a total of 126 aphids, of which 53 were vectors.  This tracks well with the 13 year average; at this point in the growing year, some alternate hosts are maturing and becoming less suitable hosts, resulting in the development of winged aphids dispersing to establish new colonies on better food sources. If we stay true to the average pattern, we can expect vector numbers to start increasing sharply (see the graph below demonstrating the average regional capture from 2013-2024).  

The traps captured a number of different vector species, however, cotton-melon aphids were widespread, both buckthorn and potato aphids were present in several sites, and we started to see the appearance of Damson-Hop aphids at multiple sites this week. Green peach aphids remained low, with only a single individual being recovered at one location.  

Keep scouting and checking predictive sites!

The usual reminder:

- 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. And to include those border crops when treating the field for colonizing aphids.

 Happy scouting and have a great weekend!

Click on any image below for full-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 7/11/2025

 Cumulative PVY Vector Risk Index by Site to 7/12/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 7/11/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 7/11/2025

 

Trap Catches July 03, 2025.

The number of aphid species in the traps rose slightly over last week, but most were non-vector species.  With 9 traps reporting, traps recovered a total of 50 aphids, only 5 of which were vectors.  Having said that, we are slightly ahead of where we were on aphids counts this time last year. In 2024, the week after July 4 had a noticeable rise in vector flight, so we'll see what comes our way... In any case, aphids are flying and our rising temperatures will increase feeding rates and subsequent reproduction, we are rapidly getting into the aphid growth days of summer.  

Vector species this week consisted mostly of corn leaf aphid, but potato and English grain aphids were also recovered. Keep scouting and checking predictive sites!

Have a great Fourth of July weekend!

The usual reminder:

- 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 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

- 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. And to include those border crops when treating the field for colonizing aphids.

 Happy scouting and have a safe and happy Fourth!

Click on any image below for full-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 6/27/2025

 Cumulative PVY Vector Risk Index by Site to 7/05/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 7/03/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 7/03/2025

 

Trap Catches June 27, 2025.

The number of aphid species in the traps rose this week. With 8 traps reporting, we had 27 vector aphids and 44 non-vectors captured. Aphids have started flying and so it's time to start scouting and applying management tools like crop oils. 

Vector species included a number of corn leaf aphids, soybean and buckthorn aphids are starting to be captured, and a number of potato aphids were recovered in at least one location. Non-vector species made up the majority of trap captures this week, but does indicate weather conditions are good for aphid movement.   

So, as a reminder:

- vector flights have started, so start 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 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

- 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. And to include those border crops when treating the field for colonizing aphids.

 Happy scouting and have a great upcoming week.

Click on any image below for full-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 6/27/2025

 Cumulative PVY Vector Risk Index by Site to 6/28/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 6/27/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 6/27/2025

 Trap Catches June 20, 2025.

The number of vector aphid species remains low in the traps this week. With 8 traps reporting, we had 13 vector aphids captured. Several traps recovered Buckthorn aphid, with soybean aphids starting to appear in Central MN. No green peach aphids have been recovered so far. 

So, as a reminder:

- vector flights have started, so start scouting; aphids can establish early after potatoes are up. Field scouting is less effective at finding aphd vector species that don't colonize potatoes. While these species will enter potato fields and probe plants, 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. Watch predictive sites (like this one) and check 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 aphid vector populations.

- 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.

 Lets hope the aphid populations stay low and we have a great season!

Click on any image below for full-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 to 6/20/2025

 Cumulative PVY Vector Risk Index to 6/28/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 6/06/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 6/13/2025