Aphid Alert 2000, No. 5, July 9

Update: Summary of virus vector situation through 9 July

To date, aphid captures in the Aphid Alert network traps have been few. Only four green peach aphids have been collected, one each at Little Falls - 26 June, Climax - 3 July, Walhalla - 7 July, and Karlstad - 10 July. On this date in 1998 and 1999, we were averaging 0.5-0.75 green peach aphid per trap.

Other aphid species (most of which are potential PVY vectors) have been more abundant, but during the week ending 14 July total captures were still in the range of 0-35 per location (i.e., 0-12 per trap).

It is possible that some locations aphids were lost from pan traps flooded by heavy rains. Note: In Minnesota, North Dakota and Wisconsin, we operate one suction trap and two pan traps at each location. Our cooperators in Nebraska and South Dakota operate a suction trap only.

Our team in the Red River Valley reports that many canola fields now have moderate to heavy infestations of green peach aphid. These populations do not appear to be as large as large as occurred last year. However, green aphid numbers likely will to continue to increase for the next several weeks.

Much of the canola in the Valley is past flowering and the lower leaves are beginning to senesce. We anticipate that as the canola matures, captures of green peach aphid captures in our traps will increase sharply.

Small grains are now maturing and it does not appear that these crops are supporting large aphid populations. Cereal aphids are potential PVY vectors, so their comparative low numbers are good news.