Friday, September 4, 2015

Trap Catches Identified to September 4

Vector numbers and PVY risk have dropped dramatically from the past two weeks.  Still seeing some bird cherry oat and soybean aphids but in much smaller numbers.  Ada led the sites with a PVY Risk of 3.15, down from 12.81 lasat week.  All other sites reporting index values below 2.0, many below 1.0.  
We've had fewer sites reporting as some are beginning to vine kill and harvest.  We will continue to report as long as we get traps in!  Good luck out there!
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.

PVY-Vector Risk Index - click on map for full size


9-4 table9-4 graph

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