Trap Catches Identified to September 18, 2020.

The season is winding down with only 4 of 20 sites reporting this week.  Very few aphids were flying; the colder temperatures and field harvest decreasing their numbers.

Interestingly, green peach aphid was still recovered from one site.  It's late appearance this year indicates we may have had a very late in-flight to the region.  

Next week we'll be presenting a wrap-up of the season and summarizing the timing of aphid flights throughout the summer.  Here's hoping everyone's harvest goes well!

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to September 18, 2020.

    

Cumulative PVY Vector Risk Index to September 15, 2019 season (for comparison)

Aphid Species Capture and PVY Vector Risk Index for the week ending September 18, 2020

Cumulative Aphid Species Capture and PVY Vector Risk Index to September 18, 2020.

 

Trap Catches Identified to September 11, 2020.

Aphid vector captures were down at all locations this week; the cooler temperatures slowing down reproduction and movement.  There were a total of 63 individual aphids from 11 different species as compared to 172 aphids from 16 vector species last week.  Still, there does seem to be several species well represented in the area.

Green peach aphids are still present, 7 being recovered from 4 locations (Humboldt, Sabin and Perham all reported GPA).  Soybean aphid numbers are lower this week, as are numbers of small grain aphids.   Thistle aphids have decreased but are still present, and buckthorn aphid numbers remain steady as they migrate back to their overwintering host.

Overall, this is an expected week, with the season winding down, many fields already vine-killed and harvest underway.  We hope all's going well for everyone in the field.

As today is 9/11, lets also take a moment to remember those brave individuals who run towards danger in order to safeguard us all. 

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to September 11, 2020.

    

Cumulative PVY Vector Risk Index to September 09, 2019 season (for comparison)

Aphid Species Capture and PVY Vector Risk Index for the week ending September 04, 2020

Cumulative Aphid Species Capture and PVY Vector Risk Index to September 11, 2020.

 

Trap Catches Identified to September 04, 2020.

Aphid vector numbers were down this week, with increasing numbers of fields being vine-killed, fewer sites are reporting.  The number of vector aphids recovered to this point in 2019 was only 2/3 of what we've captured in 2020.  Consequently, as can be seen in the map and tables below, the regional PVY Vector Risk Index is higher in 2020 than it was this time last year.  The numbers of certain species varies a bit this year, we've recovered fewer English grain aphids, but far more corn leaf aphids; the numbers of green peach aphids are very similar to last year but from different locations.  Green peach aphids seem to be more dispersed this year, 10 of the 19 sites have recovered this species (which is the most efficient vector of PVY).  

Importantly, this was the highest capture of green peach aphids we've seen so far this year.  Soybean aphid captures were up this week; we've stated to experience cooler evenings and flights to buckthorn may well make up some of these numbers.  Thistle aphid numbers were up this week, potato aphids and and small grain aphids are still well represented in the trap captures while damson-hop and cannabis aphids have decreased this week.     

While many fields have already vine-killed, it's obviously important if you have green plants still in the field to be managing aphid vectors.  Much of our within-field transmission of PVY probably occurs later in the season.

If you have a field where Colorado Potato Beetle aren’t being controlled by insecticides, please let us know.  We’d like to get samples of that population to test for insecticide resistance.  Contact Ian MacRae at 218-280-9887.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to September 04, 2020.

    

Cumulative PVY Vector Risk Index to September 01, 2019 season (for comparison)

Aphid Species Capture and PVY Vector Risk Index for the week ending September 04, 2020

Cumulative Aphid Species Capture and PVY Vector Risk Index to September 04, 2020.

 

Trap Catches Identified to August 28, 2020.

Another big aphid week leading to increasing late season PVY risk, more than doubling over last week's.  Numbers were up over last week (a total of 70 more vector aphids from all sites over last week) and several sites saw a considerable jump in the cumulative seasonal number of vectors captured and their PVY Vector Risk Index jumped accordingly.  Small grain aphids were up as well as damson-hop and cannabis aphids in a number of locations.  Green peach aphids were recovered in more locations and at higher numbers at multiple locations.

The number of vectors recovered at the Staples I location was very high (92 aphids from 10 different vector species), captures at Ada and the Nebraska I sites were also much higher than last week (26 more at Ada and 23 more at Nebraska I).  The Nebraska sites saw a flight of damson-hop and cannabis aphids aphids were also recovered from a number of locations in MN.  Green peach aphids were recovered from the Crookston, Crystal, Nebraska I & 2, Sabin and Staples II sites.  

This represents a considerable increase in late season risk of PVY transmission within seed fields.  For those who have not yet vine killed, it is worth considering.  Watch for green vines remaining in the field, from and aphid's point of view - if potatoes are green, by vectors they'll be seen!  We've all long suspected that most of the within-field inoculum movement occurs in the late season.  And the aphid dynamics indicated by the flight captures indicates why!

  

Aphid fact of the week - many aphid species don't overwinter on the same plants they feed on in the summer.  Late in the season, cold nights and shorter days signal the movement back to the overwintering plant hosts.  So late season flights may result in winged aphids (including vector species) entering potato fields where they may probe plants and spread virus.

If you have a field where Colorado Potato Beetle aren’t being controlled by insecticides, please let us know.  We’d like to get samples of that population to test for insecticide resistance.  Contact Ian MacRae at 218-280-9887.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to August 28, 2020.

    

Cumulative PVY Vector Risk Index to August 30, 2019 season (for comparison)

Aphid Species Capture and PVY Vector Risk Index for the week ending August 28, 2020

Cumulative Aphid Species Capture and PVY Vector Risk Index to August 28, 2020.

 

Trap Catches Identified to August 21, 2020.

We had another big week for aphid vector numbers, with very similar numbers to last week.  A total of 287 vectors were recovered from 15 sites reporting. In fact, with this week's catch, we've caught up with 2019 and are pretty much at the same levels, but with different levels at different sites....

A number of efficient vector species were recovered from most locations.  Green peach aphids were found in Sabin, soybean aphids had a large flight with large captures at several locations. There seems to be high numbers of thistle aphids this year and populations of damson-hop aphids have developed as well this year.  Populations of potato aphids persist and the small grain aphids (bird-cherry oat, corn leaf and English grain aphids) continue to be well-represented in trap catches.  Because many of these are efficient vectors, the PVY Vector Risk Index has risen this week to also be pretty much the same as this time last year.

Many seed fields are being vine killed and harvested.  But remember, aphids will continue to probe any green plant material in the field, so inoculum can be moved until plants are killed.

Hope harvest goes well, keep an eye on the fields... 

If you have a field where Colorado Potato Beetle aren’t being controlled by insecticides, please let us know.  We’d like to get samples of that population to test for insecticide resistance.  Contact Ian MacRae at 218-280-9887.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to August 21, 2020.

    

Cumulative PVY Vector Risk Index to August 23, 2019 season (for comparison)

Aphid Species Capture and PVY Vector Risk Index for the week ending August 21, 2020

Cumulative Aphid Species Capture and PVY Vector Risk Index to August 21, 2020.

 

Trap Catches Identified to August 14, 2020.

Aphid numbers took an even bigger jump this week with the vector numbers and the PVY Vector Risk Index tripling over last week.  Several locations had high counts which elevated PVY Vector Risk Index numbers accordingly. There were a number of efficient vectors captured at most locations, including Green Peach Aphids being recovered from both the Crookston and Hoople traps.  Soybean aphids also showed up at a number of locations, sometimes in very large numbers.  The Sabin trap had a combined 2 weeks of capture and recovered over 150 vectors, approximately half of which were soybean aphids.  Several other locations had captures that were high compared to what we've been seeing so far.

Our vector capture and risk index values are still lower than they were at this time last year.  But a large jump like this one over one week does signal we're not out of the woods for aphids yet.  Unfortunately, many of the vector species recovered this week were non-colonizing species.  So they'll move into a field, probing plants to test if they're suitable hosts, and finding potatoes not to be preferred food, move on to the next plant without leaving a daughter behind.  This means there'll be no tiny aphids on the leaves and little other sign of their presence on the plant.  So these non-colonizing species might not show up in your scouting.  That's not to say scouting isn't necessary, with the new-found presence of Green Peach and Potato Aphids in the area (which will colonize potatoes), scouting is still important.  If you're in an area with heavy counts and the situation persists next week, it might be a good to consider vine kill if you haven't already.  

Hope the season is progressing well, check out the weekly trap catches below.

If you have a field where Colorado Potato Beetle aren’t being controlled by insecticides, please let us know.  We’d like to get samples of that population to test for insecticide resistance.  Contact Ian MacRae at 218-280-9887.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to August 14, 2020.

    

Cumulative PVY Vector Risk Index for total 2019 season (for comparison)

Aphid Species Capture and PVY Vector Risk Index for the week ending August 14, 2020

Cumulative Aphid Species Capture and PVY Vector Risk Index to August 14, 2020.

 

Trap Catches Identified to August 08, 2020.

Aphid numbers took a jump this week with the total aphid numbers and the number of vector species doubling over last week.  The Damson Hop aphid, which was recovered at 3 different sites this week, Cannabis aphids also were captured this week, although only at one location.  Thistle aphids have started to appear and small grain aphids also increased in numbers.  Potato aphids remain well established in several locations.  Several of these vector species being recovered are relatively effective.  Consequently, the PVY Vector Risk Index more than doubled this week.

Even though numbers have doubled from last week, aphid captures and the PVY Risk Index values are less than half what they were at this time last year. Compared to many past years, this remains a low aphid year.  But even a few aphids can move inoculum around in a field.  So keep scouting!  

 

If you have a field where Colorado Potato Beetle aren’t being controlled by insecticides, please let us know.  We’d like to get samples of that population to test for insecticide resistance.  Contact Ian MacRae at 218-280-9887.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to August 08, 2020.

    

Cumulative PVY Vector Risk Index for 2019 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for the week ending August 08, 2020

Cumulative Aphid Species Capture and PVY Vector Risk Index to August 08, 2020.

Trap Catches Identified to July 31, 2020.

More sites captured aphids this week than last (12 of 19 reporting) but overall numbers are down a bit.  The season's vector numbers are low to this point and so the PVY Vector Risk Index remains low.  The numbers of sites reporting aphids though does mean we have winged aphids flying in the area.  

So, while aphid vector numbers may be low, they are well-distributed.  And considering the very low threshold for aphids in seed potatoes, scouting remains important.

Aphid Fact of the Week - Potato Virus Y can be acquired or transmitted by aphids vectors in less than a  minute, there is data to indicate some strains are more transmissible than others.  Virus particles are picked up on the mouth parts of winged aphid vectors when they probe potatoes to ascertain if the plant is a suitable host.  These aphids will eventually fly to and probe other potato plants, transmitting the virus particles to the new plant.  Because aphids will continue to probe plants as they cross a field, efficiently moving PVY inoculum around fields.  

 

If you have a field where Colorado Potato Beetle aren’t being controlled by insecticides, please let us know.  We’d like to get samples of that population to test for insecticide resistance.  Contact Ian MacRae at 218-280-9887.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to July 24, 2020.

Cumulative PVY Vector Risk Index for 2019 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for the week ending July 31, 2020

Cumulative Aphid Species Capture and PVY Vector Risk Index to July 31, 2020.

Trap Catches Identified to July 24, 2020.

Even though aphid numbers increased this week, they remain low with 24 vectors recovered from 9 sites of the 17 sites reporting this week.  We started to recover soybean aphids from a number of sites as well. All the data's below in the tables.

PVY Vector Risk Index is now lower than this time last year.  Small grains continue to mature and we have not yet seen a flight of cereal aphids, so this may change in the next week or two.  Overall, however, the aphid numbers appear relatively low this year..

But the presence of winged aphids does signal the continued need for scouting, we do have movement of aphids into potatoes.  If you're not already, it's time to be scouting seed (and commercial) potatoes for aphids.  

Many of the species we're recovering are non-colonizing species, meaning they may not show up when sampling potato leaves.  But their habit of moving through fields, probing plants to assess host suitability means they are still a problem!. 

Aphid Fact of the Week - There are two different types of adult aphids; winged and non-winged (referred to as alate and apterous forms respectively). The winged aphids are dispersal forms.  In summer, they're the individuals who leave colonies that are becoming stressed from densities or decreasing food quality.  In the late season, winged aphdis will return to overwintering hosts.  The non-winged aphids are colony builders, they feed on host plants, give birth to live daughters and increase the size of the colony.  A winged aphid's daughters will always be non-winged.  

 

If you have a field where Colorado Potato Beetle aren’t being controlled by insecticides, please let us know.  We’d like to get samples of that population to test for insecticide resistance.  Contact Ian MacRae at 218-280-9887.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to July 24, 2020.

Cumulative PVY Vector Risk Index for 2019 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for the week ending July 24, 2020

Cumulative Aphid Species Capture and PVY Vector Risk Index to July 24, 2020.

Trap Catches Identified to July 17, 2020.

The number  of aphid vectors remains low this week with only 12 vectors caught in from 7 sites in the 14 sites reporting this week.  We still don't have green peach aphid (cross your fingers that this keeps up!).  Potato aphids are still showing up in a number of locations, so I'm keeping the picture of these long-legged aphids up this week.  The data's below in the graphs.

The PVY Vector Risk Index is very similar to this time last year, in fact, the numbers.  We captured more aphids from more species by this time last year but the species were not as effective at vectoring PVY as the ones being recovered this year, so the Vector Risk Index remains similar.

Even though numbers are low, aphids are flying.  Which means we do have movement of aphids from other cropping systems into potatoes.  If you're not already, it's time to be scouting seed (and commercial) potatoes for aphids.  

Remember though, the aphids you don't see may be as important in transmitting PVY as the ones you do see.  Non-colonizing aphid vectors can be as important in spreading PVY as are many of the colonizing species. Colonizing aphids feed on potatoes, they'll start feeding after testing a plant for suitability as a host.  Non-colonizing aphids may not spend as much time on individual potato plants as do colonizing aphids; they don't feed on potatoes, so they probe, potentially picking up PVY if it's an infected plant, and quickly move on to another potato plant in the field. 

Aphid Fact of the Week - Aphid reproduction in the summer is parthenogenetic, unfertilized females giving rise to female offspring.  In fact, in the aphid species we monitor, there are no males during the summer.  Adult females give birth to live daughters, which, sometimes in as short a period as several days, will be giving birth to their own daughters.  This system can result in very rapid development of aphid colonies. 

 

  

If you have a field where Colorado Potato Beetle aren’t being controlled by insecticides, please let us know.  We’d like to get samples of that population to test for insecticide resistance.  Contact Ian MacRae at 218-280-9887.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to July 17, 2020.

Cumulative PVY Vector Risk Index for 2019 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for the week ending July 17, 2020

Cumulative Aphid Species Capture and PVY Vector Risk Index to July 17, 2020.