The latest Arizona Vegetable Integrated Pest Management Update from the University of Arizona (UA) Cooperative Extension in Yuma, Ariz.

Alternatives for aphid management in desert produce

By John Palumbo, UA Research Scientist and Extension Specialist

With the cold weather conditions experienced in early February, one might conclude that aphid pressure will subside. However, aphid populations monitored in untreated lettuce plots at the Yuma Agricultural Center (YAC) suggest differently.

We observed a steady increase in both green peach aphids and Acyrthosiphon lactucae, which is an aphid species specific to lettuce with no common name that occurs sporadically in desert produce.

The highest abundance recorded is about 18 aphids/plant, and on average we are finding about 4-5 aphids/plant in untreated lettuce. This is up from less than 2 aphids per plant prior to the freeze we experienced. We also observed an increase in winged (alate) aphids which is likely due to the gusting north winds experienced recently.

With warmer temperatures we anticipate these numbers to increase. You might want to pay particular attention for aphid colonization when visiting fields.

Additional notes:

Imidacloprid soil applications at 0.25 lb AI/ac (i.e., Alias 2F at 16 oz) are holding aphids to low numbers in lettuce trials at YAC.

Preliminary efficacy trials have shown that Movento, Beleaf, and Assail are maintaining green peach aphids at low levels for 14 days following sprays.

Anecdotal reports have been coming in from area pest control advisers that Foxglove aphid has been found in celery, and Lettuce "red" aphid in romaine.

For more information on the identification, biology, ecology and management of aphid species important on desert produce, check out this link: Insect Management on Desert Produce Crops: Aphids.  Also check out the Aphid Control Chart.

Contact Palumbo: (928) 928-782-3836 or jpalumbo@ag.arizona.edu.