Pre- and post-harvest strategies for leek moth control on diversified vegetable farms in Vermont

Leek moth, a pest of members of the Allium family, and whose larvae feed on crop foliage, causes stunting of plant growth, and compromises the marketable yield of fresh alliums and the quality of alliums in storage. Our team took a participatory action research (PAR) approach, inquiry in which researchers and stakeholders work together to understand a problem and identify potential solutions, to address this emerging threat to Northeastern allium production. We tested the efficacy of the commonly available generalist egg parasitoid, Trichogramma brassicae, as a biological control for leek moth, and the effect of variable “topping” lengths for the reduction in the number of leek moth exit holes and subsequent reduction in marketability of onions post-harvest. The release of T. brassicae within onion plots significantly reduced the incidence of leek moth damage in onion leaves by an average of about 50%, topped onions exhibited significantly less leek moth exit holes when compared to onions cured with intact leaf tubes and then topped before storage, and topping did not significantly affect onion quality after six months of cold storage.