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The accessions are maintained in insect proof screenhouses and tissue culture protocols to prevent reinfection. All plants are retention tested yearly to ensure the highest level of cleanliness available. 

The National Clean Plant Network-Hops (NCPN-Hops) program brings together industry leaders, plant pathologists, regulators, and clean plant centers. They work together to ensure that clean, virus-tested hop propagation material is available to the U.S. hop industry, minimizing the economic impact of damaging viruses and virus-like agents. Hops was added to the National Clean Plant Network in 2010 as industry demand for reliable sources of disease-free hop propagation material increased after hop stunt viroid was discovered in U.S. commercial production blocks in 2004.


With over 99% of the United States hop production in Washington, Oregon, and Idaho, the Clean Plant Center Northwest (CPCNW) at Washington State University - Prosser serves as the headquarters for NCPN-Hops. The Clean Plant Center Northwest maintains the NCPN-Hops foundation collection of virus-tested, G-1 hop accessions.

Our clean plant center:


Foundation level plant material is sold primarily to the nursery industry to establish healthy sources of propagation materials for commercial production. Order policies and minimums differ between centers. Please contact a center or program for specifics. 


NCPN Testimonals


  At Select Botanicals Group and Hop Breeding Company we have seen first-hand the impact widespread infection by virus and viroids can have on hop production, and therefore cannot overstate the importance of NCPN’s role as a critical and trusted link in the hop supply chain.”

Jason Perrault, Select Botanicals, Toppenish, Washington


“F&B Farms propagates clean, trusted material provided from the NCPN. With their technical support testing, cleaning, and verifying material, we can provide services that growers need.  Having the clean plant center at our back allows us to provide plants that are clean and production for the growers will be maximized.”

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“The NCPN is an invaluable resource to the Latitude 46 breeding program and is an integral part of our variety development process. The impacts on viruses and viroids on hop production can be devastating, and the hop industry recognizes the benefits of the availability of clean plants, diagnostics, and virus elimination services. “

Fred Geschwill, F&B Farms, Woodburn Oregon

Megan Twomey, Latitude 46, Washington

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