Trap Catches Identified to July 18.
Here are the trap catches from the sites we received up to July 18. Note that sites
are on different schedules to send in trap catches (spreading out our
Nate reports there are higher number of aphid vectors at the Ada,
Forest River, and Linton II sites this week. However, most sites are
still seeing very low numbers of aphids. Overall numbers are low
compared to data from the previous two years of this project and this is
most likely due to the cool weather and rain we've had this summer. As
temperatures increase we expect to see aphid numbers to increase as
Species included English grain aphid, cowpea and buckthorn aphids. No green peach or soybean aphids were recovered this week. Soybean aphid populations are low in northern MN and ND but are starting to establish in SW MN and this species is dispersed by wind.
So, until next week…
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.
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
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.