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Andy Robinson

Potato Extension Agronomist

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Aphid Alert II: Aug 8. Aphid number are increasing rapidly!

Trap catches from the Aphid Alert II suction trap network are in for the week ending Aug 8. This has been one of the biggest capture weeks so far this summer. We had large increases in almost all trap locations over last week. If you have not started aphid management, it's time to start!

Friday, August 8, 2014

Trap Catches Identified to Aug 08.
Here are the trap catches we received up to Aug 08.

aphidalert.blogspot.com OR aphidalert.umn.edu

It looks like aphids are now moving into potatoes in earnest!  We had large increases in almost all trap locations over last week.  If you have not started aphid management, it's time to start!  Nate reports that over all trap sites we collected 232 vectors this week compared to 51 last week.  Aphid populations were high across the region and many locations recorded their highest vector numbers of the season.  Only our Linton and Langdon sites saw fewer aphids this week.  Bird cherry oat aphids continue to be our most caught species followed by green bug, english grain, and corn leaf aphids.

So far, no green peach or soybean aphid (despite soybean aphids being present in soybean fields in low numbers).  If the  weather starts to favor soybean aphid reproduction, we may yet see this species moving into seed potato fields!

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.

 

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