Fireblight on Roses? - Ask Extension
As members of the Rosaceae family, are roses susceptible to fireblight? A landscape contractor told me the roses in a large, recently acquired, r...
Knowledgebase
Fireblight on Roses? #125964
Asked May 08, 2013, 12:34 PM EDT
As members of the Rosaceae family, are roses susceptible to fireblight?
A landscape contractor told me the roses in a large, recently acquired, rose garden have fireblight. I think the damage is caused by the recent cold weather and lack of protection. The mulch had been removed just prior to the cold weather. There is some blackening on some plants, and other signs I associate with winter die-back. There has been no pruning on the roses since last summer, however the person pruning them was untrained. Additionally, the roses were previously covered in vines and in poor health due to years of neglect.
A landscape contractor told me the roses in a large, recently acquired, rose garden have fireblight. I think the damage is caused by the recent cold weather and lack of protection. The mulch had been removed just prior to the cold weather. There is some blackening on some plants, and other signs I associate with winter die-back. There has been no pruning on the roses since last summer, however the person pruning them was untrained. Additionally, the roses were previously covered in vines and in poor health due to years of neglect.
Denver County Colorado
Expert Response
Fireblight is common on apple, pear, and crabapple. It affects members of the rose family, and occasionally rose as well. It is difficult to confirm from the photos whether it is fireblight or not. Fire blight cankers on branches or stems appear as dark discolored areas that are slightly sunken, with a narrow callus ridge along the outer edge. The narrow callus ridge is diagnostic for differentiating fire blight cankers from other cankers. Fireblight is most prevalent following warm, wet weather.
You mentioned that the roses were covered in vines - when were the vines removed? Sunscald combined with very cold spring weather could produce similar symptoms.
You mentioned that the roses were covered in vines - when were the vines removed? Sunscald combined with very cold spring weather could produce similar symptoms.
I have not seen any callus ridges or cankers, just areas of discoloration that are towards the outside of the plants ranging from light tan to almost black (the winter mulch was rotting on the roses with black stems). We have not had warm, wet weather this year. I believe the vines were removed summer 2011. A number of declining fruit trees that were previously identified as having fireblight are adjacent to the rose garden.
Fire blight is difficult to control and often requires a multi-faceted approach. More info can be found in the following fact sheet: http://www.ext.colostate.edu/pubs/garden/02907.html
