Aphid numbers remain relatively low. Note that we received two samples from some of our cooperators this week (Forest River, Hatton, Motley, and Staples) due to the holiday last week. Motley, Perham and Ada seeing some higher numbers than the rest of the sites. Two green peach aphids were collected this week, one from Forest River and one from Perham. Remember, the green peach aphid is by far the most efficient vector of PVY.
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.