Trap Catches to July 09, 2021.
Aphid vector catch numbers increased significantly this week with the PVY Vector Risk Index values doubling in the past 7 days. Cereal aphids are dispersing from the senescing small grains; most trapping sites reporting in the past week captured English Grain Aphids, and many reported Corn Leaf or Bird-Cherry Oat aphids. Soybean aphids have also started their summer dispersal flight with most sites recovering low numbers of this aphid. Cotton/melon and Buckthorn aphids were also recovered at several sites this week.
The weather conditions still favor aphid population development and we expect further cereal aphid flight over the next couple of weeks. The most numerous species reported this week are non-colonizing species, they don't become established on potato but they do enter potato fields and probe plants to assess if they're suitable food sources. This probing is sufficient to acquire virus particles on their mouthparts. After they determine potatoes aren't a viable food host, these aphids will fly to another plant, relatively close by and probe that one. Non-colonizing aphids will work their way across a field trying plants and moving on. Consequently, they will spread any PVY inoculum in the field. Unfortunately, because they don't form colonies on potato plants, they're unlikely to be spotted with standard scouting techniques. But colonizing species are being recovered as well, so it's still important to keep up the field scouting.
Increasing flights of colonizing and non-colonizing aphid vectors in our traps are good indications that the risk of PVY spread is increasing in the region. The use of refined crop oils may well be a good addition to management practices (see below).
We'll keep reporting numbers. As always, keep on scouting!