Trap Catches Sept 06 - Sept 13, 2024.

As the season winds down and only 3 sites reporting this week, aphid vector numbers again decreased. The average number of vector aphid species recovered per location is less than half that of last week, and the average PVY Vector Risk Index values at each location reflect that decrease.  Our average regional numbers are close to the 2012-2023 average (see chart below).  

Most locations have already vine killed and movement from other cropping systems is also declining significantly.  Even soybean aphids were low.  Good news after late season flights.

For those few locations that have not yet vine killed, remember, virus transmission remains a concern as long as plant material is green and circulating. 

Bottom line - this will likely be the last week of trap contents coming in.  Our regional populations this season closely matched the 2013-2023 average for both aphid vector numbers and PVY Vector Risk Index values in pattern and magnitude.

The top chart shows the average regional aphid vector captures/trap and PVY Vector Risk Index to Sept 13, 2024.  The lower graph shows 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).    

Scouting for aphids in potatoes:

- Select leaves from the lower to mid canopy. Start at the edge of the field.

- Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.

- Avoid leaves on the ground or in contact with the soil.

- In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.

- The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.

- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.

The PVY Risk Index Index

Not all species of aphid are equally efficient at transmitting PVY, some are better than others (green peach being the most efficient vector of PVY).  So, the total number of aphids in a trap don't necessarily reflect just how much vector pressure there is at that location.  The PVY Vector Risk Index compares aphid numbers, incorporating their relative vector efficiency compared to the Queen of PVY vectors (green peach aphid!).  Using averaged reference comparisons from the literature, we multiply the number of each aphid species captured by its efficiency compared to Green Peach Aphid to more accurately depict risk posed by the species being trapped.  We then sum the totals.  The PVY-VRI values are presented on the tables below but also on maps comparing current cumulative risk to the total risk from the sample sites of last year (to compare with your local winter grow out results).

Scouting for aphids in potatoes:

- Select leaves from the lower to mid canopy. Start at the edge of the field.

- Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.

- Avoid leaves on the ground or in contact with the soil.

- In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.

- The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.

- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to 9/13/2024

Cumulative PVY Vector Risk Index to 9/08/2023 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 9/13/2024

Cumulative Aphid Species Capture and PVY Vector Risk Index to 9/13/24

 Trap Catches Aug 31 - Sept 06, 2024.

With 5 trap locations reporting, the average number of vector aphid species recovered per location has again significantly declined this week, as has the average PVY Vector Risk Index values at each location.  The early September drop in aphid numbers agrees closely with the 2012-2023 average of regional aphid population dynamics (see chart).  

While numbers are lower, important vector species remain in the trapping area.  Both Becker, MN and Crystal ND traps recorded green peach aphids this week.  Soybean aphids are lower but still widely distributed (both MN and ND sites reported this species). Other aphid species, including non-vectors, have decreased.  

Heavy aphid infestations in central MN commercial fields have continued, becoming wide spread in some fields.  Thee higher temperatures this week may continue to drive reproduction somewhat but the cool nights will ameliorate that increase.  Many fields have been vine killed and so this is not problematic.  For those that are continuing to grow and populations are difficult to control, several aphid-targeted insecticides may be effective; Transform (Cortev; sulfoxaflor), Sivanto Prime (Bayer Cropscience; flupyradifurone), or Sefina (BASF; afidopyropen) are all effective aphicides and have performed well in field trials.

For those locations that have not yet vine killed, virus transmission remains a concern as long as plant material is green and circulating. 

Bottom line - aphid populations and PVY Vector Risk significantly decreased again over the last week. Any field that is not yet vine killed remains susceptible to potential virus transmission...  

The top chart shows the average regional aphid vector captures/trap and PVY Vector Risk Index to Sept 06, 2024.  The lower graph shows 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).    

Scouting for aphids in potatoes:

- Select leaves from the lower to mid canopy. Start at the edge of the field.

- Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.

- Avoid leaves on the ground or in contact with the soil.

- In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.

- The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.

- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.

The PVY Risk Index Index

Not all species of aphid are equally efficient at transmitting PVY, some are better than others (green peach being the most efficient vector of PVY).  So, the total number of aphids in a trap don't necessarily reflect just how much vector pressure there is at that location.  The PVY Vector Risk Index compares aphid numbers, incorporating their relative vector efficiency compared to the Queen of PVY vectors (green peach aphid!).  Using averaged reference comparisons from the literature, we multiply the number of each aphid species captured by its efficiency compared to Green Peach Aphid to more accurately depict risk posed by the species being trapped.  We then sum the totals.  The PVY-VRI values are presented on the tables below but also on maps comparing current cumulative risk to the total risk from the sample sites of last year (to compare with your local winter grow out results).

Scouting for aphids in potatoes:

- Select leaves from the lower to mid canopy. Start at the edge of the field.

- Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.

- Avoid leaves on the ground or in contact with the soil.

- In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.

- The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.

- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to 9/06/2024

Cumulative PVY Vector Risk Index to 9/08/2023 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 9/06/2024

Cumulative Aphid Species Capture and PVY Vector Risk Index to 9/06/24

Trap Catches Aug 23 - Aug 30, 2024.

With 6 trap locations reporting this week, the average number of vector aphid species recovered per location has significantly declined this week, as has the average PVY Vector Risk Index values at each location.  Our trap captures this week are about a week  earlier than the 2012-2023 average (see the chart below (see chart).  This has probably been the result of lower temperatures and increased rainfall. 

Soybean aphid captures, while still occurring at most reporting locations, are lower than the previous 2 weeks.  Likewise, small grain aphid numbers have dropped off as well.  Even non-vector species were less numerous.  

There have been reports, however, of heavy aphid infestations in central MN commercial fields.  These populations are experiencing high reproduction rates and attempts to manage their growth with synthetic pyrethroids have not been as successful as anticipated.  If synthetic pyrethroids are failing to control populations, it may be advisable to try aphid-targeted insecticides such as Transform (Cortev; sulfoxaflor), Sivanto Prime (Bayer Cropscience; flupyradifurone), or Sefina (BASF; afidopyropen). All three are effective aphicides and have performed well in field trials.

Some locations have already vine killed, but for those that have not, as long as plant material is green and circulating, the plant is still susceptible to feeding by aphids and potential virus transmission. 

Bottom line - aphid populations and PVY Vector Risk significantly decreased over the last week. Any field that is not yet vine killed remains susceptible to potential virus transmission...  

The top chart shows the average regional aphid vector captures/trap and PVY Vector Risk Index to Aug 30, 2024.  The lower graph shows 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).    

Scouting for aphids in potatoes:

- Select leaves from the lower to mid canopy. Start at the edge of the field.

- Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.

- Avoid leaves on the ground or in contact with the soil.

- In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.

- The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.

- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.

The PVY Risk Index Index

Not all species of aphid are equally efficient at transmitting PVY, some are better than others (green peach being the most efficient vector of PVY).  So, the total number of aphids in a trap don't necessarily reflect just how much vector pressure there is at that location.  The PVY Vector Risk Index compares aphid numbers, incorporating their relative vector efficiency compared to the Queen of PVY vectors (green peach aphid!).  Using averaged reference comparisons from the literature, we multiply the number of each aphid species captured by its efficiency compared to Green Peach Aphid to more accurately depict risk posed by the species being trapped.  We then sum the totals.  The PVY-VRI values are presented on the tables below but also on maps comparing current cumulative risk to the total risk from the sample sites of last year (to compare with your local winter grow out results).

Scouting for aphids in potatoes:

- Select leaves from the lower to mid canopy. Start at the edge of the field.

- Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.

- Avoid leaves on the ground or in contact with the soil.

- In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.

- The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.

- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to 8/30/2024

Cumulative PVY Vector Risk Index to 9/02/2023 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/30/2024

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/30/24

   Trap Catches Aug 16 - Aug 23, 2024.

With 9 trap locations reporting this week, the average number of vector aphid species recovered per location is slightly down from last week, but the change in species resulted in a similar level of PVY Vector Risk Index.  Our numbers and PVY Vector Risk remain very close to the 2012-2023 average (see the chart below (see chart).  The 12 year average of aphid vector populations in MN & ND indicates decreasing numbers through the end of August, but presence persists into September. 

The only aphid species with a significant drop this week was soybean aphids.  Most other vector species numbers were down slightly from last week with the exception of buckthorn, black bean, and potato aphids.  The relative efficacies of soybean and the increasing species resulted in there being little change in the average PVY Vector Risk index from Aug 16 to Aug 23.  

Some locations have already vine killed, but for those that have not, remember the adage - If leaves are green, by aphids they're seen!  Yeah, corny, but true.  As long as plant material is green and circulating, the plant is still susceptible to feeding by aphids and potential virus transmission. 

Bottom line - aphid populations slightly decreased but the vector risk remained the same as last week. Meaning any field that is not yet vine killed remains susceptible to potential virus transmission...  

The top chart shows the average regional aphid vector captures/trap and PVY Vector Risk Index to Aug 23, 2024.  The lower graph shows 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).    

Scouting for aphids in potatoes:

- Select leaves from the lower to mid canopy. Start at the edge of the field.

- Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.

- Avoid leaves on the ground or in contact with the soil.

- In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.

- The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.

- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.

The PVY Risk Index Index

Not all species of aphid are equally efficient at transmitting PVY, some are better than others (green peach being the most efficient vector of PVY).  So, the total number of aphids in a trap don't necessarily reflect just how much vector pressure there is at that location.  The PVY Vector Risk Index compares aphid numbers, incorporating their relative vector efficiency compared to the Queen of PVY vectors (green peach aphid!).  Using averaged reference comparisons from the literature, we multiply the number of each aphid species captured by its efficiency compared to Green Peach Aphid to more accurately depict risk posed by the species being trapped.  We then sum the totals.  The PVY-VRI values are presented on the tables below but also on maps comparing current cumulative risk to the total risk from the sample sites of last year (to compare with your local winter grow out results).

Scouting for aphids in potatoes:

- Select leaves from the lower to mid canopy. Start at the edge of the field.

- Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.

- Avoid leaves on the ground or in contact with the soil.

- In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.

- The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.

- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to 8/23/2024

Cumulative PVY Vector Risk Index to 8/25/2023 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/23/2024

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/23/24

  Trap Catches Aug 09-Aug 16, 2024.

With 11 traps reporting, the average number of aphid vectors captured per trap across the region remained similar to last week. There were, however, some important differences; the average captures of small grain aphids was slightly below last weeks, while the numbers of soybean aphids increased, especially at two trap locations. Our PVY Vector counts and PVY Vector Risk Index values remain behind those of 2023, and we continue to see very similar levels as the 12-year average for number of vectors per trap and PVY Vector Risk Index. The top graph below is the current regional average PVY Vector data to 08/16/2024, the bottom graph is the average PVY Vector data from 2013-2023.  The X-axis is the ISO week of the year, the graphs are arranged so the ISO weeks correspond. 

Soybean aphids continue to increase as their seasonal dispersal continues. This will likely continue until our nightly temperatures drop into the 40'sF.  Green peach aphid captures increased over last week, and were captured from 4 locations, with the trap at Becker, MN  returning 6 of the wee beasties. Small grain aphid numbers were lower than last week, which is not surprising given many locations are already harvesting wheat. As with last week, many of the aphid species recovered do not colonize potato. So, we'll keep counting for now.

Bottom line - The aphid populations were off to a slow start but we are now very close to the average 2012-2023 averages. The recent rains in some of our locations may slow aphid population growth but the 12-year average population declines don't occur until the end of the month.  

Scouting for aphids in potatoes:

- Select leaves from the lower to mid canopy. Start at the edge of the field.

- Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.

- Avoid leaves on the ground or in contact with the soil.

- In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.

- The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.

- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.

The PVY Risk Index Index

Not all species of aphid are equally efficient at transmitting PVY, some are better than others (green peach being the most efficient vector of PVY).  So, the total number of aphids in a trap don't necessarily reflect just how much vector pressure there is at that location.  The PVY Vector Risk Index compares aphid numbers, incorporating their relative vector efficiency compared to the Queen of PVY vectors (green peach aphid!).  Using averaged reference comparisons from the literature, we multiply the number of each aphid species captured by its efficiency compared to Green Peach Aphid to more accurately depict risk posed by the species being trapped.  We then sum the totals.  The PVY-VRI values are presented on the tables below but also on maps comparing current cumulative risk to the total risk from the sample sites of last year (to compare with your local winter grow out results).

Scouting for aphids in potatoes:

- Select leaves from the lower to mid canopy. Start at the edge of the field.

- Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.

- Avoid leaves on the ground or in contact with the soil.

- In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.

- The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.

- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to 8/09/2024

Cumulative PVY Vector Risk Index to 8/11/2023 for Comparison

Aphid Species Capture and PVY Vector Risk Index for the week ending 8/16/2024

Cumulative Aphid Species Capture and PVY Vector Risk Index to 8/16/24