Aphid Alert 1999, No. 1, February 10

Data from aphid-trapping in 1998

Photograph above from UC Statewide IPM Project

Seasonal flight activity of green peach aphid (primary vector of PLRV)

Week 1, 1998. Aphid trapping was begun the last week of June. The dots (actually circles) on the map represent sample locations. In all maps, the area of the circle is in proportion to numbers of aphids captured per trap. During the first week of trapping no green peach aphids were captured. To view any image in greater detail click on image.

Week 2, 1998. Trapping network was still under construction. Traps were operating only at Little Falls, Hollandale, Morris, and Lamberton. A single green peach aphid was captured at Morris, which was most likely a spring migrant arriving from its overwintering site.

Week 3, 1998. Trapping network has been established except the site at Karlstad. A single green peach aphid was captured at Morris, and 10 green peach aphid was captured at Climax.

Week 4, 1998. Large colonies of green peach aphids containing all life stages and forms (winged and wingless) has been found in a canola field near Crookston, MN. Green peach aphids were captured at Waseca (4), Climax (1), and Karlstad (1).

Week 5, 1998. Sporadic green peach aphid captures occurred across the trapping network, Little Falls (1), Hoople (1), Cando (1), and Rolette (1). Green peach aphid colonization of seed potato fields had begun. The numbers of wingless green peach aphids found at Hoople and a field near Grafton had exceeded treatment threshold.

Week 6, 1998. Green peach aphids were captured across the trapping network indicating that summer migration of green peach aphid is now occurring throughout the Red River Valley. Green peach aphids were captured at Lamberton (1), Little Falls (1), Climax (2), Hoople (12), Cando (8), and Rolette (1).

Week 7, 1998. An increase of green peach aphid captures has been observed across the trapping network indicating the increased flight activity of summer migrants. Inspectors of the Minnesota Department of Agriculture have also reported an increase in seed potato fields colonized by green peach aphids. Green peach aphids were captured at Hollandale (2), Waseca (3), Lamberton (2), Morris (2), Baker (1), Climax (5), Karlstad (14), Hoople (31), Cando (12), and Rolette (46).

Week 8, 1998. Green peach aphids were captured across the trapping network indicating that summer migrants of green peach aphid are now occurring throughout the State. Green peach aphids were captured at Hollandale (2), Lamberton (2), Morris (12), Little Falls (3), Baker (3), Climax (16), Karlstad (10), Williams (2), Hoople (21), Cando (13), and Rolette (22).

Week 9, 1998. Green peach aphid capture continued to increase and colonization of potato fields were a common occurrence across the Valley. In potato fields where aphid management did not follow recommendations, result of large-scale aphid colonization is especially striking. In these fields severe aphid pressure did not only caused aphid holes but also whole fields were killed prematurely by aphids. Green peach aphids were captured at Waseca (2), Lamberton (3), Morris (1), Little Falls (1), Baker (3), Climax (57), Karlstad (25), Williams (6), Hoople (67), Cando (2), and Rolette (9).

Week 10, 1998. Green peach aphid flight activity was generally similar to that of previous week. Aphid holes had been observed on seed potato fields. Green peach aphids were captured at Morris (4), Little Falls (1), Climax (71), Karlstad (13), Williams (2), Hoople (26), and Rolette (1).

Week 11, 1998. Green peach aphids flight activity decreased across the State. Green peach aphids were captured at Little Falls (1), Climax (4), Karlstad (4), Williams (1), Hoople (6). There were no traps at Hollandale.

Week 12, 1998. Green peach aphids were captured only at Hoople (5). There were no traps at Rolette.

Week 13, 1998. No green peach aphid capture. There were no traps at Lamberton, and Little Falls.

Week 14, 1998. Green peach aphids were captured at Climax (1), and Williams (1). There were no traps at Morris.

Seasonal flight activity of potential PVY vectors

Week 1, 1998. Few PVY vectors bird-cherry oat aphids and English grain aphids were captured at Little Falls and Hollandale.

Week 2, 1998. PVY species capture increased in the southern sites.

Week 3, 1998. Increased flight of PVY vectors with the largest aphid capture at Climax. Sunflower and grain fields in close proximity to the Climax trapping site are most likely responsible for the large numbers of aphid caught at Climax.

Week 4, 1998. PVY vector capture almost doubled in Climax and Hoople. Substantial numbers were also caught at Karlstad. However, the southernmost site, Baker and the northernmost sites Williams, Cando and Hoople had lower captures than the central Red River Valley.

Week 5, 1998. There was a general increase in PVY capture across the Red River Valley. This increase corresponds to the buildup of aphids in maturing small grain fields, weeds and other crops.

Week 6, 1998. There was a rapid increase of PVY vector capture this week. Sunflower aphids were abundant at all sites of the Red River Valley and over 70% of aphids captured were sunflower aphids at Climax and Hoople where the highest capture occurred.

Week 7, 1998. Aphid captures begun to decline at the southern sites while they peaked at the northern sites. Sunflower aphids were the dominant species at all sites.

Week 8, 1998. Flight activity of PVY vector species declined across the Red River Valley.

Week 9, 1998. Similar flight activity of PVY species to the previous week. Week 10, 1998. Rapid declined flight activity of PVY vector species signaling the end of PVY vector flight activity.

Week 10, 1998. Rapid declined flight activity of PVY vector species signaling the end of PVY vector flight activity.

Week 11, 1998. Only sporadic capture of PVY vector species across the trapping network.

Week 12, 1998. Only sporadic capture of PVY vector species across the trapping network.

Week 13, 1998. Only sporadic capture of PVY vector species across the trapping network.

Week 14, 1998. Only sporadic capture of PVY vector species across the trapping network.

Recommendations for virus control in seed potato production