Virus in Dahlias – Become Part of the Solution!

One of the opportunities that has evolved from the virus work at Washington State University is for you to become an important part of the solution to the problem of virus in our dahlia patches.  There are two key items that need to become a part of your routine practice in your garden.  First is to watch for the appearance of virus on the leaves of your plants.  Virus symptoms were illustrated in the brochure distributed in the June, 2016, ADS Bulletin and those pictures can also be found on the ADS Website,  If the foliage on your plants match the appearance of the leaves in the brochure, the plant(s) should be removed from the garden and destroyed in an area away from the garden.  Aggressive implementation of a “remove and destroy” strategy on a dahlia garden has been shown to lead to a virtually virus-free garden!  However, you could also be removing some plants that don’t need to be removed.  An intermediate approach that has been available at the WSU Clean Dahlia Center is to test your dahlias for virus.  That way you will know which of those suspicious-looking plants really has virus.  In 2017 and 2018, testing was available at a subsidized rate of 30 samples for $300.  The rate was made possible by the cooperation of Professor Hanu Pappu and the financial support of the Scheetz-Chuey Foundation.  We hope to be able to establish a similar arrangement for 2019.

It is virtually certain that your garden contains a mix of clean and virused dahlias.  Some of the plants with virus could lack any evidence of virus on the foliage.  When you work in your garden, there is a very real risk that you can and will move virus from the virused plants over to the clean plants unless you disinfect your tools between each plant.  A 10% bleach solution is the “gold standard” for disinfecting your tools but there are a couple more options listed in the table below. 

The dishwashing detergent has the advantage of avoiding the damaging effect of the bleach on the metal in your tools.  It is also readily available and inexpensive.  The Virkon S is an anti-viral product that is routinely used in veterinarian cleaning applications.  It is readily available from internet suppliers.  (My grandchildren tell me to “just Google it!”)  Please be aware that anti-bacterial products like hand sanitizer can be completely ineffective in killing virus. 

Disinfecting your tools is an essential part of dividing your clumps.  There is no more aggressive “attack” on your plants than When you divide those clumps into tubers.  

Disinfecting Options

  • 10% Solution of Bleach
  • Dawn Dish Soap 4 tsp in 5 cups Water
  • Virkon S

Be sure to have one of the sterilization options sitting on your cutting bench to sterilize those cutting tools between each clump.  I will have two or three cutters and both the bleach and soap solutions on my bench.  The tools will be used in turn.  Each will get a bleach dip and a soap rest while waiting for the next clump!

To become part of the solution of the dahlia virus problem; 1) Remove obviously virused plants from your garden and 2) Disinfect your tools between working on different plants.

Professor Hanu Pappu, Ron Miner and the Virus Team: Brad Freeman, Nick Weber, Jerry Moreno, and Linda Taylor