BIOS Field Day at Unruh Farms

In continuing to promote the Biologically Integrated Orchard Systems (BIOS) project, Community Alliance with Family Farmers (CAFF) held its third field day event hosted at Unruh Farms located in Princeton, CA., on June 16th. The event focused primarily around beneficial insects in orchard systems, and how the incorporation of diversified species of cover crop plays a critical role. As an added bonus, the 30 attendees were treated with first-hand demonstrations of a predatory mite release and application of predator attractants by host Daniel Unruh.

Hanna Kahl, CAFF’s Ecological Pest Management Specialist, started the meeting by welcoming attendees and highlighting CAFF’s mission objectives, results from year one of the BIOS project, and the variety of resources for farmers. She introduced the host and farmer Daniel Unruh and UC ANR entomologist & IPM specialist Amber Vinchesi-Vahl Ph.D. 

Daniel Unruh presenting his custom-built mite blower used in the predatory mite release demonstration.

Daniel Unruh is a 2006 transplant from South Dakota and has been farming the land surrounding his home since 2010. He started off by discussing the different setbacks he has faced with his farming operation. Early on, he encountered nematode issues post-planting, which led to him incorporating brassica cover crops to suppress the nematode population; he has continued to plant cover crops in his orchard ever since. On top of that, he also had a large spider mite population which can cause severe defoliation of trees. He found that he could control spider mites by releasing predatory mites which are voracious spider mite predators, and spraying “predator food” (soy flour, protein formula, sugar/sucrose, and nutritional yeast) mixed with wintergreen oil (which contains a plant volatile compound that signals attack by herbivores) to attract and retain natural enemies. 

Miguel Alvarez and Hanna Kahl examining a yellow sticky card used to monitor beneficial insects.

After discussions of how to best manage cover crops and promote beneficial insects, the group moved to the orchard for first-hand demonstrations of a predatory mite release and predator attractant application. Using his custom-built mite blower, Daniel demonstrated how he releases predatory mites into the tree canopy, focusing on the edges of the orchard that are most susceptible to damage. He then applied the minty-smelling predator attractant mix to encourage movement of beneficials into the orchard. In addition to these demos, Miguel Alvarez, a field technician for the BIOS project, showed the group how to properly monitor natural enemy populations using yellow sticky cards he had set up in the orchard as part of CAFF’s preliminary experiment on the effects of the predator attractant mix on predators and spider mites. 

Following the in-field demonstrations, Amber Vinchesi-Vahl spoke on the importance of arthropod natural enemies in controlling pest populations, and led the group through an identification guide for common arthropod natural enemies. Chris Ball from Rincon-Vitova Insectaries followed this discussion with a walk-through of multiple live natural enemy samples brought, including lacewings, lady beetles, and even some praying mantis egg cases. 

Amber Vinchesi-Vahl walks through the natural enemy identification guide.

Despite the heat, attendees were happy to walk the orchard and get close-up looks at Dan’s custom-built equipment. Many left with samples of beneficial insects, and hopefully a deeper understanding of the importance of promoting biodiversity within orchards.