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!
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).
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)