Field efficacy trials of Metarhizium anisopliae alone and in combination with entomopathogenic nematodes against the larval stage of the Carrots Rust Fly Psila rosae

We are working directly with organic growers to help them make management decisions to minimize damage cause by the Carrot Rust fly larvae, based on monitor for Carrot Rust Fly adult using yellow-orange visual sticky traps. In addition, we are testing selected entomopathogenic nematodes to determine their effectiveness against the soil dwelling larval stage of the carrot rust fly. All experiments were done on organic farms in Western Washington. Eleven farmer volunteered to monitor for the pest and were given a training in how to put traps out and identify the adult stage of the pest. Only one farm had populations levels significant enough to justify any action to mitigate potential damage by the larval stage. At Terry’s Berries, carrots were treated with three different nematode species to compare their effectiveness for protecting carrots from larval damage. At the time of writing this, the treated carrots are still in the field so no data is available for this year. Last years results demonstrated that the entomopathogenic nematode, Steinernema feltiae, gave significant protection against this pest. This year we tested S. feltiae and two other species as well, Heterorhabditis marilatus; Heterorhabditis bacteriophora. All three species were treated at a
high (7.4 x 108 juveniles/acre) and low dose (2.2 x 108 juveniles/acre). In addition to the entomopathogenic nematodes, the fungal pathogen Metarhizium anisopliae has shown great promise as a tool to protect carrots from this pest. Due to EPA registration problems, this product was not used in these experiments this year.

Grant Information

  • Project ID: 012
  • Project Status: Complete


  • Principal Investigator(s): Muehleisen, D.
  • Grant Amount: $16,139