About Us

The Clean Plant Center Northwest (CPCNW) is a part of the National Clean Plant Network and is based at Washington State University (WSU) Prosser Irrigated Agriculture Research and Extension Center.

With funding from USDA, WSU, and commodity groups, we work closely with fruit tree, grape, and hop industries to propagate, distribute, and maintain virus-tested fruit trees, grapevines, and hop plants at our facilities in WSU-Prosser. Our connection to the agriculture industry ensures we continue to provide plant material that is relevant and economically important to each commodity. Our philosophy of “start clean, stay clean” emphasizes the importance of planting with clean materials to ensure high-quality production from orchards, vineyards, and hop yards. We provide clean plant material to nurseries, growers, and other research agencies. The clean ‘mother’ plants in our greenhouses, screen houses, and foundation vineyard are a cornerstone in the Pacific Northwest fruit trees, grapes, and hops industries.

Through our virus diagnostic lab, we offer custom testing for viruses and virus-like agents in a variety of commodities. Our diagnostic lab helps inform our research, as we aim to better understand the viruses and virus-like agents that cause plant diseases. By understanding the biology of the diseases and their associated pathogens we can develop improved pathogen detection, therapy, and management strategies. Science-based detection and management strategies allow growers to make informed decisions to help minimize the economic losses caused by virus-like agents. Viruses can move quickly through an industry and have devastating effects on yield, produce quality, and long-term sustainability. For example:

The Northwest hop industry is fighting a disease caused by Hop stunt viroid (HSVd). Depending on the hop cultivar, the disease reduces yield by as much as 70 percent.

The picture shows the lime green leaves symptomatic of HSVd.

Little cherry virus 2 causes cherry trees to produce small, flavorless fruit. This disease is an ongoing threat to Northwest cherry orchards.

The picture shows cherries picked from healthy trees compared to cherries picked from diseased trees.

Wine grapes are susceptible to Grapevine leaf roll disease. Infected vineyards exhibit red-colored grape leaves with a downward curl. Wine grapes with this disease take longer to ripen, if they ripen at all.

The picture shows a Grape leafroll disease-infected plant.




Apple green crinkle disease causes deformed apples and severely impacts yield.

The picture shows symptoms of apple green crinkle disease.