Potato Extension


Andy Robinson

Potato Extension Agronomist


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Aphid Alert II

Aphid Alert II trap catches for the week ending Aug 15 are now available. Aphid vector numbers in seed potatoes took a huge jump this past week with capture numbers doubling at most locations! Vector species captured include lots of small grain aphids (not surprising given maturing small grains), green peach aphid from two locations, and soybean aphid from multiple locations. Aphid scouting and management should be well underway! If you're in a position to kill vines early, consider it. Most of our PVY is transmitted in the late season.
Hi folks!
Vectors have nearly doubled this week with 18 sites reporting.  444 aphid vectors were collected this week as compared to 232 last week.  Ada, Crookston, and Forest River had especially high numbers while Hallock, Hatton, and Staples recorded mid range numbers and the remaining were relatively low.  Soybean aphid populations have begun to blossom in a few areas while bird cherry oat, corn leaf, and green bug continue to make up a majority of aphids captured.  This week we also collected some green peach from Staples and Crookston.  Remember that a lot of PVY transmission happens late season and high numbers of aphids are a large factor in this!
If you have not yet begun aphid management, it is important to do so.
So Keep Scouting!
Scouting for aphids in potatoes:
- Select leaves from the lower to mid canopy.  Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy.
 - Avoid leaves on the ground or in contact with the soil.
 - In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY.
 - The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.
- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.
More information at www.aphidalert.blogspot.com ro aphidalert.umn.edu
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