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.
