Locking the doors to rose black spot

Authors: ZLESAK, DAVID - UNIVERSITY OF WISCONSIN; ZURN, JASON; HOKANSON, STAN - UNIVERSITY OF MINNESOTA; Bassil, Nahla; BRADEEN, JAMES - UNIVERSITY OF MINNESOTA

Submitted to: American Rose
Publication Type: Trade Journal
Publication Acceptance Date: 8/30/2020
Publication Date: 9/1/2020
Citation: Zlesak, D., Zurn, J.D., Hokanson, S., Bassil, N.V., Bradeen, J. 2020. Locking the doors to rose black spot. American Rose. September/October:75-81.

Interpretive Summary: As rose lovers, few things make our hearts skip a beat more with excitement than a garden filled with blooming, healthy roses. As rosarians we try to be proactive to minimize threats to our roses thriving. For those of us in humid/wet climates (for even just part of the year) one of the greatest threats is rose black spot disease. This fungal disease can spread quickly and lead to defoliation. The outcome is dramatically reduced growth and blooms. The primary way to deal with black spot, and other fungal diseases, has traditionally been routine, preventative fungicide sprays. Fortunately, over the past couple decades, there has been great strides made towards breeding roses with elevated levels of black spot resistance. A number of researchers around the world have worked to gain a greater understanding of the genes contributing to resistance. We are grateful to be among the scientists on this adventure. Over the past few years, we have been able to make some notable advances with support from the USDA grant, “RosBREED: Combining Disease Resistance with Horticultural Quality in New Rosaceous Cultivars.” Although the grant mainly focused on fruit crops in the rose family, we are grateful our rose work was able to be included. Our team is located at different institutions, and we have brought our unique areas of expertise together to significantly push the understanding of resistance to black spot forward. We’ll share a bit of background on rose black spot disease, our recent contributions, and how this knowledge can support rose lovers with improved cultivar.

Technical Abstract: As rose lovers, few things make our hearts skip a beat more with excitement than a garden filled with blooming, healthy roses. As rosarians we try to be proactive to minimize threats to our roses thriving. For those of us in humid/wet climates (for even just part of the year) one of the greatest threats is rose black spot disease. This fungal disease can spread quickly and lead to defoliation. The outcome is dramatically reduced growth and blooms. The primary way to deal with black spot, and other fungal diseases, has traditionally been routine, preventative fungicide sprays. Fortunately, over the past couple decades, there has been great strides made towards breeding roses with elevated levels of black spot resistance. A number of researchers around the world have worked to gain a greater understanding of the genes contributing to resistance. We are grateful to be among the scientists on this adventure. Over the past few years, we have been able to make some notable advances with support from the USDA grant, “RosBREED: Combining Disease Resistance with Horticultural Quality in New Rosaceous Cultivars.” Although the grant mainly focused on fruit crops in the rose family, we are grateful our rose work was able to be included. Our team is located at different institutions, and we have brought our unique areas of expertise together to significantly push the understanding of resistance to black spot forward. We’ll share a bit of background on rose black spot disease, our recent contributions, and how this knowledge can support rose lovers with improved cultivars.