Just a quick update on aphids in the field. – from Chris DiFonzo

Aphid numbers are still variable across the state. However, in areas where aphid numbers have increased, the increase was incredibly FAST. For example, numbers at the Bean and Beet research farm south of Saginaw went from 10-20 per plant to 500-600 per plant in just seven days. Overnight, from the day of counting, plants went from ‘clean looking ’ with 500-600 aphids per plant, to honeydew-covered with even more aphids per plant. Not only are aphids increasing, but winged aphids are also distributing around the landscape, and adding new babies to plants. Last week, the trap on the MSU campus had the highest winged trap catch (96 aphids) of any of the suction traps running in the Midwest.

Areas reporting increasing aphid populations – Drier areas across the state; Saginaw County; Kalamazoo County; Hillsdale (Jerome area); NW Ohio and southeast Michigan.

Insecticide update:

• We have sprayed several plots in the last two weeks for aphids. Our observations mirror what we’ve seen in the past. Lorsban = exceptional kill in hot weather (remains to be seen if recolonization will occur with all of the winged aphid production). Warrior – working well. A few aphids left after spraying, but overall looks good. Other products were Ok 4-7 days after treatment. Will have further data on longevity of treatments in the next 1-2 weeks as we continue to count plots.
• Organic spray trial at the Bean and Beet Farm: Pyganic does little against SBA, as we’ve observed in the past. Corn syrup – does less than nothing on SBA, despite its alleged properties. Citric acid = some potential aphid reduction, but a bit too early to tell?. We need to respray these plots, and will have additional counts in the next 1-2 weeks.
• Seed treatments = Seed treated beans are being colonized, and in fact went over threshold at heavy aphid sites, at the same time as the untreated beans. The seed treated beans are taller than the untreated, but it appears that the lethal levels of treatment are no longer present in the plant. We have large seed treated and untreated plots (plus large block of Cruiser sprayed and unsprayed) so that we can take and compare yields in the fall.

Respray: I have reports of plots sprayed early, in late June / early July, being recolonized by aphids. This is not a surprise, as early sprays killed predators, and some may have been suboptimal (tank mixed w/ glyphosate). Also, insecticides sprayed 2 weeks ago have broken down and there is no residual left to kill the winged aphids colonizing these fields. Watch early sprayed fields closely, because they may need to be treated again.

Opportunities to learn about aphids/ scouting/ or products:
July 27-28th: MSU Diagnostic day
Aug 4th: Field day at John Diehl’s place in Mason
Aug 30th: Field Day at the Bean and Beet farm in Saginaw

Chris

p.s. CORN ROOTWORM UPDATE – Rootworm adults are emerging. – My untreated plots in various studies have lodged – First root washing rating will begin at the end of the week of July 25, so you may bring roots to campus after that. I will leave pools out at the MSU Ent Farm. label each root w/ masking tape.

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