Seed Gall Nematodes in Grasses Grown for Seed: Survey and Identification Methods

July 2023 | 26 mins., 57 sec.
by Hannah M. Rivedal and Inga A. Zasada
Oregon State University


​Grasses grown for seed are produced in Oregon and travel around the globe through international and domestic trade. Plant-parasitic nematodes can cause costly export rejections if phytosanitary requirements are not met. In the grass for seed cropping system, Anguina seed gall nematodes can contribute to significant export rejections. This webcast provides information on seed gall nematodes and their relationship to grass species. Topics include the sampling methods and timings that are best for identifying these nematodes in annual ryegrass and orchardgrass seed fields in Oregon, as well as the challenges of both traditional nematology extraction methods and molecular testing for these nematodes in soil, tiller, and seed samples. By the end of this presentation, farmers, diagnosticians, and other practitioners should have an understanding of the Anguina seed gall nematode life cycle, methods for surveying fields, and best practices for either nematode extraction or molecular testing of plant materials. 

About the Presenter

Hannah M. RivedalHannah M. Rivedal obtained her PhD from Oregon State University and is a research plant pathologist in the USDA-ARS Forage Seed and Cereal Research Unit in Corvallis, Oregon. She has more than 10 years of plant pathology research experience in specialty crops, including 2 years as a plant disease diagnostician. Her current research program is dedicated to understanding the biology, epidemiology, and impact of pathogens on crop and seed health within seed crop production systems. Her program focuses on turf, forage grasses, and legumes grown for seed in Oregon and the Pacific Northwest.  

Inga A. ZasadaInga A. Zasada is a research plant pathologist with the USDA-ARS and a Courtesy Associate Professor at Oregon State University. Her interest in nematology began as a Peace Corps volunteer in Malta, where she worked on developing management strategies for the plant-parasitic nematodes associated with potatoes and other crops on the islands. She received a PhD in plant pathology from the University of California, Davis. Inga joined the USDA-ARS Nematology Laboratory, Beltsville, Maryland, in 2003. During her tenure, she led a national effort to implement a biosolid amendment product into a diversity of crop production systems for plant-parasitic nematode management. She also continued research on understanding the underlying mechanisms of nematode suppression with cover crops and organic amendments. In 2008, Inga accepted a position in the USDA-ARS Horticultural Crops Research Laboratory, Corvallis, Oregon. Her research program focuses on the management of plant-parasitic nematodes in small fruits, potatoes, and other high-value crops. She was part of the Globodera Alliance, a multistate project on potato cyst nematodes in the United States; her research focused on the biology, pathogenicity, and genetics of Globodera ellingtonae. She is also part of the newly funded SCRI project Potatoes & Pests Actionable Science Against Nematodes (PAPAS).

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