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RRD information email from Dr. Mark Windham to me yesterday.

3 years ago
last modified: 3 years ago

My email and his reply are self explanatory.

NOTE: His reply was inserted with red into my email and the red did not come over when I copied and pasted so I made his replies in Bold and Slanted, hope that works. Not a lot new except in regards to the removal of limbs vs. entire plant but we each make our own choice on that. He asked me to share here for those that may not be aware of some of the safeguards and remind us that things change as research continues.

Windham, Mark T Dr <>

Betty, I answered you questions below. My comments are in red. Hope this helps.


Dear Dr. Windham,

Could you please clarify ongoing concerns I have about RRD that I could not find answers to in my research or the links you sent in August, 2019. Reminder: You graciously answered several questions I had in 2019 and as they say, “a good deed seldom goes unpunished”. So, here I am again with additional concerns.

I have read that:

  • RRD cannot be transmitted via sap on clippers. I know other disease can be transmitted on pruning equipment but at this time my concern is RRD.
  • That the mite does not live more than 24 hrs. when not on a host. The mite can live to up to 5 days off a host (usually 3 days)
  • That we can remove a limb rather than the entire plant if the disease is discovered immediately. This is not true. Many people try this; there is about 25% chance of success – not good odds even for Vegas. If a bush has it, get it out of there. If you can’t get it out when detected, cut out the rosette and remove bush as soon as possible.

Of Concern- In preventing the transfer of the mite from one bush to another, it seems that my gloves or possibly my clothes would be an equal or greater transmitter of the mite than the clippers.

Previously I have done the following to discourage the disease:

  • Sprayed with a suggested miticides alternating products. Forbid (21 days) my first choice. I do not want to harm beneficials.
  • Cleaned pruning equipment between rose bushes using Lysol Disinfectant Spray with Bleach. (impossible to get these days so using off brand wipes from Home Depot without bleach). Without bleach is best. Bleach corrodes pruner edges.
  • Kept rose limbs from touching each other – good idea
  • Kept my roses limited to the back yard where I have a solid wood 9’ fence. another good idea. This helps more than you think.
  • Had my yard maintenance men discontinue blowing in my back garden except right after a miticide spray. I would never use a leaf blower near roses.
  • Sent RRD samples to Texas A & M to verify the disease. Have A & M confirm that the mites were no longer present on the samples sent after bushes were sprayed. I did this when I last discovered the disease in my garden. Excellent

I have not had an outbreak in about 2 years. Since Dallas is a hot spot your previous suggestions and my above mentioned efforts must be helping somewhat. I replaced and replanted several bushes last fall and this spring. As you know it takes a few years for our roses to reach their full potential. I do not have the years in front of me to start my English garden anew after this, so I am doing all I can to limit or omit a reoccurrence of RRD.. I am reaching out to see if there is anything else I can do with special concern over transfer of active mites on gloves and clarification on the proper cleaning of secateurs. It seems you are doing all that can be done. I would not worry about mites on clothes. If there are mites about, they will be more in the air than on your clothes. They do not have wings, so they can fly off of you if they land on you.

I hope you know that all rosarians appreciate the work you and others are doing in the fight to eliminate or control RRD in our gardens. Thank you for the kind words. All the best to you. MW

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