Aphid Alert 1998, No. 6, September 4

Features of this issue

  • Aphid flight activity to date
  • Aphid flight activity 17-28 August

Welcome to the final issue of Aphid Alert. Our goal in publishing this newsletter was to provide information concerning aphid flight activity in the Red River Valley. We hope that you found the data on aphid flight activity accompanied with articles on aphid identification, biology and management useful in your decision making.

We would like to express our gratitude to the following cooperating seed potato growers in Minnesota: Peter Van Erkel, Hollandale; Robert Anderson, Little Falls; Brian Halverson, Baker; Jerry Larson, Climax; Justin Dagen, Karlstad; Scott Pieper, Williams; and in North Dakota: Brad Nilson, Hoople; Henry Miller, Cando; and Jim Jorde, Rolette.

Aphid traps were collected by the following seed potato field inspectors of the Minnesota Department of Agriculture: Dr. Willem Schrage (director), Michael Horken, Darrell Anderson, Charles Steinke, Donna Omdahl, Michael Bothum, Perry Paschke, Brent Amundson; and field inspectors of the North Dakota State Seed Department: Dr. Hossien El-Nashaar (director), Michael Oosterwijk, David Drechsel, and Richard Bares. Their help was greatly appreciated. Duane Preston, Yvonne Hanson, Dr. Robert Holder, Dr. Ian McRae and staff members of the University of Minnesota Northwest Agricultural Experiment Station, Crookston also provided valuable technical assistance. The project was funded by the 1998 Minnesota State Legislature.

Aphid Trapping

Aphid flight activity was generally similar to that of the previous week (Figure 1, Table 1). However, green peach aphid captures continued to increase and colonization of not only table stock but also seed potato fields is now a common occurrence across the Red River Valley. Aphid holes, where aphids are so dense that they are killing the plants (for more information please refer to the previous issue of Aphid Alert) have also been observed on seed potato fields. Remember, the threshold to initiate successful aphid control is very low, only 3 aphids per 100 leaves. However, by this time of the year the best management option left for seed potato growers is to kill the vines as early as possible to prevent late season virus infection. Early vine kill is especially necessary under this year’s severe aphid pressure. Current data from Hollandale and Little Falls are unavailable.

Have a safe harvest, and successful re-certification!

Figure 1. Aphid captures on the seven sampling dates, 1998

graph showing aphid captures on the seven sampling dates in 1998

Table 1. Aphid species (% of total capture, 08/17-08/28) *
*: in traps with >50 aphids / trap a sub-sample of 50 aphids
**: only 2 green tile traps

  Baker Climax
seed
Climax **
process
Karlstad Williams Hoople
seed
Hoople **
process
Cando Rolette
green peach aphid 1.7 5.2 5 8.8 4.8 10 4 1.1 3
PVY-vectors                  
birdcherry-oat aphid 5.1 2   1.5 7.6 2 2 3.8 0.5
corn leaf aphid 6.8 1.6 1 4.9 37.1 1.6   1.1 0.5
English grain aphid                  
green bug                  
pea aphid                  
potato aphid 0.6 0.8 2 0.5 1.9 7.2 12 0.5  
sunflower aphid 48.9 53.6 60 38.5 29.5 44.8 54 56.5 63.5
thistle aphid 2.3 0.8   3 2.9 2.8   0.5 1
turnip aphid 0.6 4.8 10 9.3 3.8 1.2 2 1.1 1.5
Identified non-vector species 5.6 0.2 0 0.3 1 0.4 2 0.5 0
Total # captured 484 2774 185 631 182 925 350 258 1002