Wednesday, October 9, 2013

The Aphid Alert Season Summary

What I would define as a high aphid number year has come to a close.  Most trap locations had at least moderate total seasonal trap catch numbers and some much higher.  There were 4 locations whose total seasonal trap catch exceeded 200 individual aphid vector; Walhalla, Hatton (which had close to 250), and the Linton II (which had close to 300) ND sites and Staples MN.  Much of this resulted frm later season flights.  The Linton II trap had high aphid captures throughout most of the summer and then their numbers declined later in the season.  Alternatively, most of the seasonal catch in the other 3 locations resulted from one or two very high weekly captures; in Hatton and Staples this was the sample period ending Aug 23, Walhalla had two significant flights during the Aug 23 period and then again 2 weeks later in the period ending Sept 6.

Many of the other sites also had high catch numbers; the Linton I site, Hoople and Forest River in ND and Gully in MN all captured close to or in excess of 100 individual aphid vectors.  There were a number of sites that would be categorized as having moderate numbers of seasonal catch; Lake of the Woods, Crookston, Erskine, Sabin, and Perham MN all had seasonal cpatures of close to or exceeding 50 individual aphid vectors.  The remaining sites (Cando ND, Stephen and Syre MN) all had lower capture numbers but traps there still recovered important vector species.

This year's results seem to support the idea that most of our aphid flight, and therefore most of our virus movement, occurs later in the season.  The application of crop oil and antifeedant insecticides have potential to decrease virus movement within fields but it may be that killing vines prior to some of the heaviest aphid flights may also decrease the introduction and movement of inoculum.  Given our late planting and drought conditions in many locations this season, this obviously would have been a difficult year to implement this tactic.

The Aphid Alert II network will be back next year, we are hoping to increase the number of traps and refine the resolution of our network.  Thanks and appreciation are due to all of our cooperators - we are hoping you're willing to host again next year and we'll soon be in touch regarding storing and servicing the traps.  I hope harvest went well for all.

Cumulative Seasonal Catch (click on the image for larger version)

Cumulative Seasonal Catch (click on the image for larger version)