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Andy Robinson

Potato Extension Agronomist

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Aphid Alert up to August 1

Aphid counts were down this week over last with only the Ada site reporting more than 10 vector species individuals. Even numbers of non-vector aphid species were down this week, indicating that aphid flights were suppressed but warmer temps, especially nights, may well drive numbers higher (or then again, maybe autumn is coming - nothing would surprise me about this summer!). Bird cherry oat aphids were again the most numerous vector species and was recovered from 13 of the 18 sites reporting. No green peach aphids or soybean aphids were recovered in any trap but green peach aphids were found in our greenhouse on potted potato plants. We suspect they were already present in low numbers and the warmer days increased their reproductive rate in the greenhouse.

Trap Catches Identified to Aug 01.
Here are the trap catches we received up to Aug 01.

Aphid counts were down this week over last with only the Ada site reporting more than 10 vector species individuals.  Even numbers of non-vector aphid species were down this week, indicating that aphid flights were suppressed but warmer temps, especially nights, may well drive numbers higher (or then again, maybe autumn is coming - nothing would surprise me about this summer!). Bird cherry oat aphids were again the most numerous vector species and was recovered from 13 of the 18 sites reporting.  No green peach aphids or soybean aphids were recovered in any trap but green peach aphids were found in our greenhouse on potted potato plants. We suspect they were already present in low numbers and the warmer days increased their reproductive rate in the greenhouse.

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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