It looks like the cooler weather has begun to decrease aphid numbers. We are reporting two weeks worth of data for the Hatton and Tappen sites, and in each case there is a significant reduction in total vectors and PVY risk. Green peach numbers are down and soybean aphids have dropped dramatically in all locations except Ada.
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 colonizach ap Cattion 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.
Cumulative PVY-VRI Risk Map for Trap Catch up to Aug 24 and Total for 2014 (click on map for full size )