Talking Integrated Pest Management at Blossom Farms

The Community Alliance with Family Farms (CAFF) hosted our fourth Biologically Integrated Orchard System (BIOS) field day, titled “Effective IPM Strategies for Major Walnut Pests,” at Blossom Farms on July 12th. Attendees gathered in the cover cropped orchard to discuss their observations and management strategies for key walnut pests this season.

Hanna Kahl, CAFF’s Ecological Pest Management Specialist, kicked off the event by introducing CAFF and the BIOS project, which began in the 1990s and involved some growers in the same neck of the woods as Blossom Farms. The BIOS project is now collaborating with Blossom Farms to assess the effectiveness of mating disruption, cover cropping, and natural enemy releases in reducing pest populations. 

Hanna Kahl explaining CAFF programs and resources to growers at the beginning of the field day.

The group then migrated to a shaded walnut orchard, where Mike Devencenzi, Blossom Farms’ Pest Control Advisor (PCA), shared the history of Blossom Farms and the different practices that the grower, Randy Rajkovich, employs within the orchard. Mike recounts how Randy started planting cover crops in 2010 to combat soil compaction and to incorporate biomass into the soil. Randy also owns his own seed drillers, and plants cover crops on other farms in the area. Another interesting installation of Blossom Farms is an owl box by the driveway, which Randy installed to control gophers; he has found better control in his walnuts, since his apples are too closely planted for owls to fly through. 

After this introduction, Mike brought out different traps used to monitor pest populations. He discussed how to most effectively deploy these traps, what lures to use in specific conditions, and how to make management decisions based on pest numbers. The whole group discussed the methods they use to control codling moths, aphids, spider mites, and walnut husk fly. The discussion highlighted the importance of a whole systems approach, which focuses on not disrupting beneficial insect populations, efficient water management, and promoting soil health. 

Mike Devencenzi putting a trap back into a tree after showing and explaining the uses of different traps in monitoring.

Following these discussions, Jhalendra Rijal, the UC Cooperative Extension IPM Advisor for Stanislaus County, presented pest numbers from the 2022 season so far. Jhalendra highlighted that codling moth and navel orangeworm (NOW) numbers are low at the moment, but to keep an eye on NOW as their numbers can rise exponentially near harvest time. Jhlanedra then discussed some of his ongoing research projects on walnut husk fly management, particularly identifying potential alternatives to the limited management options growers have now. 

Jhalendra Rijal explaining population trends of common walnut pests.

To wrap up the event, Hanna presented the results of the BIOS project at Blossom Farms. Although only mating disruption targeting codling moth was set up at Blossom Farms, NOW was reduced in the block with mating disruption compared to without. This may be because nuts damaged first by codling moth early in the season are easier for NOW to also infest. Hanna also discussed how cover crops may have enhanced minute pirate bugs, a spider mite predator, at Blossom farm. 

This field day at Blossom Farms gave everyone the opportunity to learn from experts in pest management as well as share their own perspective and experience on pest management. We hit on broad impacts of cover cropping to specifics of lure types. Participants were able to add additional pest management techniques to their toolkit from this event.