Cankers on Knockout Rose canes - organic remedy ?

Asked March 6, 2016, 3:48 PM EST

Good Afternoon. Using the Missouri Botanic website site's photos I identified the blackened areas on my knockout roses canes as cankers. If I was to prune out all of the effected canes there would only be a few of the smallest left. I read that copper fungicide may be effective. May I have your insight on the best way to move forward? Prune? Treat with copper or another alternative? Sadly I located the issue as I was pruning this year and now understand these new wounds are susceptible to the disease. Thank you for your guidance.

Alexandria Virginia

1 Response

We would suggest that you prune six inches or so below the affected wood. Good hard pruning will be good for your knockout roses. Now is a good time to be pruning. vw