Trap Catches to September 12, 2025. 

With vine killing occurring throughout the region, only 8 traps reported this week. Average numbers per trap were well down (~1/3 of the last trapping period); it seems the September population crash is underway. While most species were represented across the region, average capture of all species was down. Vector species were still recovered however.
Green peach aphid was recovered at one location, soybean and buckthorn aphids were the most numerous species recovered across the region. Several other species were present at various locations. The colder nights are, however, likely decreasing activity and numbers are anticipated to decrease through the next couple of weeks. 
Have a great week, and hope your harvest is going well!

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 Cumulative PVY Vector Risk Index by week for 2025. 

Cumulative PVY Risk Index by Site to 8/29/2025

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/29/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/29/2025

 Trap Catches to September 05, 2025. 

With 13 of 22 sites reporting, aphid numbers were up from our last report. Approximately 30% increase in the total capture of vector species and, averaged over the fewer traps reporting, a 50% increase in vector capture per trap location. Similar increases were seen in non-vector species, so aphid flight increased definitely had an upturn during the last trapping period. The continuing captures of green peach aphids resulted in another jump in both the total cumulative and regional average PVY Vector Risk Index. 

Average green peach aphid captures per trap were similar to last week's and The Queen Of Vector Aphids remains well represented across the region. This late season appearance is very concerning and presents a risk to any field not yet vine killed. While most of our PVY transmission likely occurs later in the season when aphid flights peak, numbers of green peach aphids at this time are especially concerning.

Soybean aphid numbers were recovered at almost every location and the number per location rose. Cotton melon, buckthorn and thistle aphids were well represented and their numbers were all higher as well. 

Historically, our numbers tend to crop the first or second week of September, and we had some colder nights this current week. Hopefully this will soon result in the development of winged generations that will leave the summer hosts. In the meantime, vector numbers remain high, so in those fields that are still green, take appropriate scouting and management steps. 

Have a great weekend, 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 Cumulative PVY Vector Risk Index by week for 2025. 

Cumulative PVY Risk Index by Site to 8/29/2025

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/29/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/29/2025

 Trap Catches to August 29, 2025. 

With 19 of 22 sites reporting, aphid numbers were only slightly lower than the last trapping period but traps recovered almost twice the number of Green peach aphid across the region. This caused the PVY Vector Risk Index to bump up a bit despite lower numbers.  Green Peach Aphid were recovered at several sites across the region again this week; it is now widely distributed across the region with only 6 sites not capturing green peach aphid this summer. 

Captures of non-vector species were the same as last week indicating aphid flight is not yet decreasing. Our vector numbers and PVY Vector Risk Index are both still far below those of last year at this point in time. However, the late season rise in green peach aphid captures (of the season's 38 GPA captured, 28 were caught in the past two trapping periods) have resulted in higher populations of that species than past year.   

The continuing aphid captures does indicate the potential for aphid outbreaks in remaining commercial fields as well. So scouting both seed and production fields until vine kill is recommended.   

The most numerous aphid vector captured across the region remains to be Soybean aphid. Small grain, potato, cotton melon, and buckthorn aphids were all well represented in trap captures. 

Have a great Labor Day weekend, 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 Cumulative PVY Vector Risk Index by week for 2025. 

Cumulative PVY Risk Index by Site to 8/29/2025

 Cumulative PVY Vector Risk Index by Site to 8/30/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/29/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/29/2025

Trap Catches to August 22, 2025. 

With 15 of 22 sites reporting, aphid numbers are lower than the last trapping period with the average catch per trap roughly 2/3 that of last week. Green Peach Aphid were recovered at several sites across the region again this week (so check individual trap location captures below). Captures of non-vector species were significantly lower than last week's. The decreased vector capture has lowered our projected PVY Vector Risk Index; our numbers are now far lower than last year's at this point in time. Predicted lower night temperatures over the next week may signal several species to develop winged generations for dispersal back to overwintering hosts.

Green peach aphid numbers were low, but slightly more numerous than last week and were recovered from 4 locations. These and last week's reports indicate green peach is likely widely distributed at low levels across the region. The sudden increase of green peach aphid captures accompanying the widely distributed storms in the region over the past weeks raises questions about the potential of storm fronts contributing to late season aphid outbreaks. 

The continued capture of green peach aphids is concerning for both seed and production fields. Not only are they the most efficient vector of Potato Virus Y, but their rapid reproduction can lead to explosive increases in numbers. Last year, several locations across the region saw expanding aphid populations that caused yield impact.  Scouting both seed and production fields is strongly recommended.   

The most numerous aphid vector captured across the region this trapping period was again Soybean aphid although numbers were lower than last week's. Small grain aphids were still common, as were potato, cotton melon , and buckthorn aphids. 

The decrease in aphid captures is moving us lower than the 12yr average capture rates. If capture rates continue to decrease, we may end up at a lower risk than anticipated. But the widely distributed presence of green peach aphids means continuing scouting and management. 

 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 Cumulative PVY Vector Risk Index by week for 2025. 

Cumulative PVY Risk Index by Site to 8/22/2025

 Cumulative PVY Vector Risk Index by Site to 8/23/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/22/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/22/2025

  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

 Trap Catches to August 08, 2025. 

(sorry for the late post, transportation difficulties delayed the completion of Aphid Friday)

With 20 of 22 sites reporting, aphid numbers were down across the region again this week, perhaps a reflection of wet conditions over the previous week. Captures of other species of flying insects were down as well in most trap locations, indicating lower insect flight over all. Traps recovered only half the number of vector aphids as the previous week with non-vector numbers being lower as well. While rainstorms that include high wind have been shown to decrease aphid numbers, it's important to remember that fields that are already colonized may still have significant populations, maintaining current scouting activities is important. 

The most numerous vector this week was Soybean aphid with corn leaf aphids also increasing as its host plants mature. Both cotton melon and potato aphids remained well represented in the region and several sites showed an increase in thistle aphid. There were no new reports of green peach aphid.

This puts us behind the 13 year average on number of aphids but in the ball park for PVY Vector Risk Index values. Many of the species captured this year have had relatively high REF values (see the explanation of the PVY Vector Risk Index below). So scouting and active management till vines are killed is still recommended - as harvest nears, remember, green vines are still attractive to aphids probing plants ('If it's still green, by an aphid it can be seen!").

 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 8/08/2025

 Cumulative PVY Vector Risk Index by Site to 8/09/2024 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/08/2025

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/08/2025

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