Seed gall nematodes in grasses grown for seed: Survey and identification methods

Authors: Rivedal, Hannah; Zasada, Inga

Submitted to: Grow: Plant Health Exchange
Publication Type: Abstract Only
Publication Acceptance Date: 7/14/2023
Publication Date: 7/14/2023
Citation: Rivedal, H.M., Zasada, I.A. 2023. Seed gall nematodes in grasses grown for seed: Survey and identification methods. Grow: Plant Health Exchange. https://doi.org/10.1094/GROW-REG-07-23-001.
DOI: https://doi.org/10.1094/GROW-REG-07-23-001

Interpretive Summary: Oregon specializes in production of grasses for forage, including annual ryegrass (Lolium multiflorum) and orchard grass (Dactylis glomerata) seed. These grass species are hosts of Anguina funesta and Anguina spp., respectively, which cause yield-limiting seed galls and can vector Rathayibacter spp., toxic bacteria to grazing livestock. Export countries have strict regulations against these pathogens. Current best practices for determining Anguina infestations in grass seed fields focus on post-harvest seed evaluation for nematode presence. Methods to evaluate fields before harvest, could reduce the number of contaminated seed lots prepared for shipment overseas. In this webinar, we provide information on our efforts to evaluate timing, collections, and detection methods, to generate new recommendations for Anguina spp. survey best practices.

Technical Abstract: Oregon’s grass for seed industry is valued at $500 million and produces 70% of the world’s grass seed. Oregon specializes in production of grasses for forage, including annual ryegrass (Lolium multiflorum) and orchard grass (Dactylis glomerata) seed. These grass species are hosts of Anguina funesta and Anguina spp., respectively, which cause yield-limiting seed galls and can vector Rathayibacter spp., toxic bacteria to grazing livestock. Export countries have strict phytosanitary regulations causing rejection of seed lots infested with the vector nematodes, a costly expense for Oregon growers. Current best practices for determining Anguina infestations in grass seed fields focus on post-harvest seed evaluation for nematode presence. These methods do not allow a grower to determine a field’s risk of Anguina spp. infection before harvest. Methods to evaluate fields before harvest, could reduce the amount of contaminated seed prepared for shipment overseas and lead to fewer seed lot rejections. In this webinar, we provide information on our efforts evaluate timing, collections, and detection methods, to generate new recommendations for Anguina spp. survey best practices. We discuss the most appropriate nematode extraction methods, morphological identification characteristics, and molecular tools available to diagnostic and testing laboratories. We provide recommendations on survey and sample size from grass seed fields and seed lots.