Disease resistant roses

Asked March 22, 2020, 1:12 PM EDT

After many years of fighting black spot on our numerous roses, I pulled them all out a few years ago and swore I'd never grow another rose. However, I read about new varieties--Knockout, etc. that are disease resistant, hardy, bloom non stop, etc. I am tempted and seduced by these claims but am skeptical. Do you know of any studies, research etc. you might recommend that was done in our climate and area? Thank you

Washington County Oregon roses knockout roses

1 Response

Our area is famous for roses. The International Rose Test Garden is in Washington Park. However, as we are all aware, roses do have their problems, and black spot is one of the worst. Selecting disease resistant roses makes it much easier to grow beautiful flowers. This article has good information on these roses, Disease Resistant Roses make gardening life Easier https://www.oregonlive.com/hg/2017/02/disease-resistant_roses_make_g.html.

There are preventative steps you can take to prevent black spot, which is caused by the fungus, Diplocarpon rosae. Like most funguses it likes moist cool conditions. The key to managing fungal diseases is moisture control, especially avoiding wet leaves. Wet leaves favor fungus, dry leaves favor good rose health. Water at the base of the plant rather than using overhead sprinklers. Space plants to encourage good air circulation. Good air movement within the plant helps dry leaves, so prune the rose to open up the center. This hellps air move to dry the leaves. Sanitation, removing black spot infected leaves, as well as any diseased or damaged stems, placing them in a bag and putting them in the trash is also important. This insightful article discusses the main diseases and problems in roses and how to manage them, Controlling Diseases and Aphids on your Roses https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1520.pdf

May you enjoy beautiful, healthy roses.