Trap Catches Identified to September 13, 2019

Greetings

The season is winding down with only 3 trap locations reporting this week.  Aphid numbers are decreasing in the reporting locations, harvest has begun.

Ada MN has had high aphid numbers for the entire season but vector numbers were down by half of last week's.  The trap at Crookston had lots of insects but no aphids, the Humboldt MN trap recovered only 5 vectors and 6 total aphids.  Corn Leaf, Cotton/Melon and Soybean aphids were the most common species recovered overall this week.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to September 13, 2019.

Cumulative PVY Vector Risk Index for 2018 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for Sept. 06 - 13, 2019

Cumulative Aphid Species Capture and PVY Vector Risk Index to Sept. 13, 2019

Trap Catches Identified to September 09, 2019

Greetings

Aphid captures per location were similar to last week, but fewer locations are reporting with the waning season. A wide variety of species were captured this week, including some efficient vector species. Green Peach Aphid numbers were down to only 3 this week from 2 locations (Crookston and Syre MN).  With this week's capture, we are still tracking higher than last season's totals and the PVY Vector Risk Index values. 

Ada MN again led aphid captures this week with 76 total vectors being recovered, including Soybean, Corn Leaf, Sunflower, Potato and Cotton/Melon aphids. Crookston and Syre both recovered Green Peach Aphids this week and increases in their PVY Vector Risk Index. 

Aphids continue to be entering potato fields in numbers and Oil and early vinekill are recommended practices to decrease late season movement of PVY.  Remember: If Potatoes Are Green, By Vectors They'll Be Seen!
  
Aphid Fact of the Week - The low evening temperatures and decreasing photoperiod will be signalling aphids currently on their summer hosts to develop a winged generation, which will disperse back to overwintering hosts.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to September 09, 2019.

Cumulative PVY Vector Risk Index for 2018 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for Aug 30 - Sept. 09, 2019

Cumulative Aphid Species Capture and PVY Vector Risk Index to Sept. 09, 2019

Trap Catches Identified to August 30, 2019

Greetings

Aphid captures were up from last week, with 151 vectors being recovered from traps. A wide variety of species were captured this week, including some efficient vector species. The capture of 14 Green Peach Aphids from 3 locations (Ada, Crookston and Syre MN) caused a big increase in the PVY Vector Risk Index values in those locations.  With this week's capture, we are tracking higher than last season's totals, with potentially 2 weeks of trapping remaining.  Some locations are vine killing this week and will discontinue trapping. 

Ada MN again led aphid captures this week with 100 total vectors being recovered, including 7 Green Peach Aphids! This caused doubled the vector risk index for that location. Several other important vector species were also recovered from the Ada trap this week.  Syre also recovered numerous vectors this week (37) including 6 Green Peach Aphids and also saw a increase in its PVY Vector Risk Index. 

Aphids continue to be entering potato fields in numbers and Oil and early vinekill are recommended practices to decrease late season movement of PVY.  Remember: If Potatoes Are Green, By Vectors They'll Be Seen!
  
Aphid Fact of the Week - Aphid species that colonize potatoes, including Green Peach Aphids, preferentially colonize the field edge first, later dispersing into the rest of the field.  This may be a response to the contrast of the green canopy to the bare soil at the headland of potato fields.  If that is the case, it underscores the importance of scouting and protecting plants until vinekill is complete.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to August 30, 2019.

Cumulative PVY Vector Risk Index for 2018 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for Aug 24-30, 2019

Cumulative Aphid Species Capture and PVY Vector Risk Index to Aug 30, 2019

Trap Catches Identified to August 23, 2019

Greetings

Aphid captures dropped this week with only 91 vectors being recovered from traps. With grain being harvested, the first flush of cereal aphids seems to be decreasing.  Numbers of English Grain aphids were down across the region, but numbers of Bird-cherry Oat and Corn aphids were rising (although far less than English Grain aphids over the past 2 weeks).  Green Peach aphids continue to be present in the region with two locations each capturing one of these highly effective vectors.

Ada remains the hot spot for aphid captures with 60 aphids being recovered this week, almost half of which were Corn Leaf aphids.  Soybean aphids are still being captured but numbers remain low. Black bean aphid and Cotton/ Melon aphids were some of the other more common aphids recovered in traps this week. 

With this week's catch, the PVY Vector Risk Index is still tracking closely to that of last year.  I have heard that some growers will be initiating vine kill in the next week.  Not a bad decision; the presence of green plant material means there can still be transmission of PVY.   Aphid dispersal events are continuing and scouting and oil applications are again strongly recommended! 
  
Aphid Fact of the Week - Throughout the growing season, the aphid vector species we follow reproduce asexually; there are no males, no eggs and offspring are deposited as live nymphs on plants that are appropriate food sources. 
In the late summer / fall, decreasing night temperatures, daylight hours and food quality will trigger the development of a winged generation of male and female winged, reproductive aphids.  These winged reproductive stages will attempt to disperse to specific plant species, often different plant species from those upon which they've feed throughout the growing season.  Sexual reproduction will occur on these plants (referred to as the Primary Hosts) resulting in eggs that will overwinter on the Primary Host. 
Some of the vector species of importance, including Green Peach Aphid, probably don't make it through our winters due to the lack of specific primary host plants species or adverse climatic conditions (it's not easy to make it through the Polar Vortex!)

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to August 23, 2019.

Cumulative PVY Vector Risk Index for 2018 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for Aug 16-23, 2019

Cumulative Aphid Species Capture and PVY Vector Risk Index to Aug 16-23, 2019

Trap Catches Identified to August 16, 2019

Greetings

It's been another big week for aphids with 200 plus aphids being recovered in the traps - of course, almost 100 of those came from one trap (must have been a busy week for aphids in Ada, MN!).  Lots of cereal aphids and a few Green Peach Aphids again this week, and a real mix of species at several locations...

The trap at Ada, MN recovered almost 100 aphids this week, more than half of which were English Grain Aphid (this doubled the PVY Vector Risk Index values for Ada).  Cereal fields in the region have turned and are coming up on harvest, explaining the movement of cereal aphids.  Never-the-less, 58 English Grain aphids in one week was a big capture!  Other than that, Cotton/Melon and Thistle Aphids were captured at several locations.  Soybean aphids have also been increasing (but are still at very low numbers) at a number of locations.  Green Peach aphids were recovered at 1 location this week..  

The PVY Vector Risk Index has doubled again this week and is on track with last year's.  Seems 2019 is quickly making up for a low start.  

If potatoes still have green leaves, there can still be transmission of PVY.  Aphid dispersal events are continuing and scouting and oil applications are again strongly recommended! 

Aphid Fact of the Week - Many of our PVY vectors don't overwinter in NW MN and NE ND.  Those that do generally will be seeking overwintering hosts within the next month.  For many of these species, this will also mean the development of male forms and eventual sexual reproduction which leads to the production of eggs (the overwintering stage of many of these species).    

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to August 16, 2019.

Cumulative PVY Vector Risk Index for 2018 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for Aug 09-16, 2019

Cumulative Aphid Species Capture and PVY Vector Risk Index to Aug 09-16, 2019

Trap Catches Identified to August 09, 2019

Greetings

Sorry this is late getting out this week, I was on a road trip collecting Colorado Potato Beetles for resistance bioassays and didn't get back till late last night.  If I'd known what was waiting in the trap samples, I might have stayed on the road...

Aphid numbers took a big jump this week, with some important vector species (including Green Peach Aphid) making appearances.  The cumulative seasonal catch increased by almost 50% with just last week's catch (our total vectors captured was 214 last week, in the past week, traps captured a total of 197 vector species across the region).  The Vector Risk numbers rose accordingly, doubling over last week.  Especially with the first seasonal appearance of Green Peach Aphid, the most efficient vector of PVY.  

Green Peach aphid was recovered at 4 locations in northwest/west central MN (Gully, Humboldt, Lake of the Woods and Sabin).  Potato aphid, another important vector species that colonizes potatoes, also saw increases and distribution. 

Most vector species were recovered in increased numbers at many locations, but the crown for numbers this week again goes to English Grain Aphid, which was recovered at most trap sites.  The other small grain aphids, Corn Leaf and Bird-Cherry Oat aphids, also increased in numbers and locations being trapped.  This increase in cereal aphids at this point in the season is due to the rapid senescence of grain fields and is an important factor in the late season transmission of PVY in seed potatoes in MN & ND.  Soybean aphids have started to be more widely recovered, but in limited numbers.  Thistle, Buckthorn and Cotton/Melon aphids also seem to be on the wing and turned up in numbers at several locations.

Bottom line - aphids are flying, the late summer dispersal events have started and scouting and weekly oil treatments are strongly recommended.  Some early fields may be nearing vine kill - this may well be a season where early vine kill may decrease PVY infection in seed potato fields.

Aphid Fact of the Week -  Maturation is occurring in crops other than cereals, and aphids will be sensing a decreasing food quality there as well.  Aphids in these crops will also eventually be developing a winged generation which will disperse to find better food sources.  Many of these species will be non-colonizing species in potato and will work their way through fields, probing and testing plants as potential hosts.  In this way, an increased movement of PVY can occur.  The later development of aphids in the northern plains is evident by the seasonal flight dynamics monitored by the Aphid Alert trapping network.  Our peak flights tend to be in late July to early August (a benefit of living in the home of the Polar Vortex?).  Weekly trap catches are available on the archived Aphid Alert Blogs, going back to 2012 on this site.    

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to August 09, 2019.

Cumulative PVY Vector Risk Index for 2018 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for Aug 02-09, 2019

Cumulative Aphid Species Capture and PVY Vector Risk Index to Aug 02-09, 2019

Trap Catches Identified to August 02, 2019

Greetings
Trap counts for the Aphid Alert Network continue to rise; higher catches were seen in all sites reporting.  The Ada MN trap reported a total of 42 aphids from 8 different vector species.  The Crookston, Gully and Staples trap sites all reported double digit catches of vectors as well. A number of different vector  species were recovered but no Green Peach Aphids so far.  As expected, a lot of sites were reporting cereal aphids, especially English Grain Aphid - this species seems to have had a good year...

The overall PVY Vector Risk Index values remain similar to those of last year but we are catching up... If aphid numbers continue to increase, the PVY Vector Risk Index could quickly rise.

Aphid Fact of the Week -  Many aphid species, including many of the aphids that vector PVY, have a strong preference for eating a particular species of plant during the summer season. As our summer progresses and many of those plant species mature and their physiology changes, the nutritional quality of their sap decreases.  Aphids, in response, will eventually develop a generation of winged aphids which will disperse, seeking food of greater nutritional value.  This is why our aphid catches tend to rise later in the season and we begin to recover species like the cereal aphids.

As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to August 02, 2019.

Cumulative PVY Vector Risk Index for 2018 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for July 19-26, 2019

Cumulative Aphid Species Capture and PVY Vector Risk Index to July 26, 2019

Trap Catches Identified to July 26, 2019.

Greetings
The trap counts are up in several locations and the cereal aphids are starting to fly.  It looks like the late July / early August vector flights are starting.  Trap catches are up overall and the hotspot this week was Crookston and Ada reporting 22 and 20 vector aphids each.

Most spots are reporting some cereal aphids, mostly English Grain Aphid and some Corn Leaf Aphid, not a lot of Bird-Cherry Oat Aphid so far this year.  Several sites reported Soybean Aphid, so the Sturgis Dispersal Event (thanks Bruce Potter for one of the most evocative terms for a dispersal event) seems to be on time, albeit very small because of the very low numbers in most parts of the North Central region.  This dispersal is unlikely to develop into much of a problem in most locations given the low number of individuals involved and the maturity of soybeans in most locations.

Other species with higher populations this week included Cotton Melon and Black Bean aphids.  Damson Hop aphids and Cannabis aphids were absent this week.

So, it looks like things may be heating up.  And this means so are the chances for the spread of PVY.  Remember, the application of oil is recommended as a mechanism of reducing the spread of PVY.

Aphid Fact of the Week - Many of the aphid species that vector (transmit) PVY in potatoes will not colonize potatoes.  At this time of year, many aphid species develop a winged generation to disperse from host plants that are beginning to senesce (like cereal crops) and are seeking greener fields (literally).  When they enter a potato field, they will probe a plant to determine if it's a suitable food host, somewhere they can leave a daughter to start a new colony.  Aphid species that can feed on potato will leave a live daughter and may feed for a period before moving on.  Aphids for whom potatoes are not a food source will continue through a field probing plants until they eventually leave the field.  This probing activity can move any PVY virus present in the field to uninfected plants.  The more aphids crossing the field, the greater the chances for PVY movement.  So while aphids colonizing potatoes are a sign that PVY spread may be occurring, the absence of aphid colonies on potato plants doesn't mean it isn't happening. Using trap data (suction or pan), sticky cards, field scouting, etc will all contribute to good estimates of vector presence.

 As always, keep on scouting!

Click on any image below for full-scale version.

Cumulative PVY Vector Risk Index to July 26, 2019.

Cumulative PVY Vector Risk Index for 2018 (for comparison)

Aphid Species Capture and PVY Vector Risk Index for July 19-26, 2019

Cumulative Aphid Species Capture and PVY Vector Risk Index to July 26, 2019

Trap Catches Identified to July 19

Greetings!

Trap catches for the week of July 12-19 have increased but are still relatively low.  We now have 12 traps reporting and several more will com online next week.  No Green Peach Aphid to this point but we recovered 2 Damson-Hop aphids and 1 Cannabis aphid.  These populations are lower than last year but we're still including them in our Risk Index calculations.  Soybean aphids remain low but are starting to show in a couple of traps. Most of the other aphids recovered in traps this week were the usual suspects for this time of year, including Cotton/Melon, Black Bean, and Thistle aphids.  Small grain development is advancing and aphid populations in cereals have been noted in a number of locations.  So we can soon expect to start recovering cereal aphids in the traps (and because the 3 most frequent cereal aphid species in MN & ND are PVY vectors, we'll be watching!) 

While numbers are still low to this point, aphids are flying and, if you haven't started scouting, it's time to start. The absence of aphids on potatoes, however doesn't mean there's no risk of PVY.  Non-colonizing aphid vectors can be as important in sp[reading PVY, if not more so, than many of the colonizing species. Remember, the application of oil is recommended as a mechanism of reducing the spread of PVY. 

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. 

As always, keep on scouting!

Cumulative PVY Vector Risk Index to July 19, 2019

Cumulative PVY Vector Risk Index for the 2018 Season (for comparison) 

Aphid Species Capture and PVY Vector Risk Index for July 12-19, 2019

Cumulative Aphid Species Capture & PVY Vector Risk - To July 19, 2019.

Trap Catches Identified to July 12

Greetings!

Trap catches for the week of July 05-12 remain low.  However, 1 Damson-Hope aphid was recovered from Gully, MN.  This aphid has been reported as being ~1/2 as efficient as Green Peach Aphid, meaning it could be a major player in spreading PVY if we see numbers this season.

Data from other researchers continues to highlight the value of early application of crop oils (e.g. Aphoil, JMS Stylet oil).  Researchers in New Brunswick have also reported additional value in adding either lambda-cyhalothrin insecticides (e.g. Warrior II, Silencer, Grizzly, etc) or the insecticide, Beleaf to oil applications.  All products should be suitable for tank mixing with fungicides (but remember to always check the label! a jar test may also be useful if you have concerns).  No other insecticides tested were found to provide additional efficacy.

While numbers are low to this point, aphids are flying and, if you haven't started, it's time to start...

As always, keep on scouting!

 Cumulative PVY Vector Risk Index Map to June 30, 2019

For Comparison - Cumulative PVY Risk Index For 2018 Season

Aphid Species Capture & PVY Risk July 05-12

Cumulative Aphid Species Capture + PVY Risk - To Week of July 12, 2018