Hop Testing & Therapy

The Clean Plant Center Northwest provides testing services to growers, propagators, regulatory agencies, and researchers. We can test for the viruses and virus-like agents listed below. Additionally, if plant material tests positive for targeted pathogens, therapy can be initiated to develop propagative material that has been cleaned of economically significant diseases. Please contact CPCNW for information on the fees for these services.

copped hops in heat chamber

At left: Hop plants receiving treatment in heat therapy chamber.




Virus-like agents commonly tested for in hop plants include:

Pathogens of concern in North America:
  • Hop stunt viroid
  • American hop latent virus
  • Hop latent virus
  • Hop mosaic virus
  • Apple mosaic virus (a.k.a. Prunus necrotic ringspot virus – hop isolate)
Of less concern in North America:
  • Apple fruit crinkle viroid (not known to occur in North America)
  • Arabis mosaic virus
  • Strawberry latent ringspot virus
  • Cherry leaf roll virus
  • Phytoplasma (not known to occur in hop in North America)
  • Hop latent viroid

Testing Fees and Sample Submission

A signed Testing Agreement must be submitted before pathogen testing can commence.

Virus Therapy Techniques

We use a variety of techniques to rid hop plants of viruses, including:

  • Meristem Culture
  • Heat Therapy & Meristem Culture
  • Chemotherapy & Meristem Culture
  • Cold Therapy & Meristem Culture


Please contact Martin Joseph for questions regarding our virus testing and therapy services for hops.