Harnett County,
North Carolina

Cooperative Extension 

How can I fight this black spot on my roses?

ASK THE HORT AGENT

Question How can I fight this black spot on my roses?

Answer Black spot disease and beauty are at odds in the modern day “War of the Roses.” The original War of the Roses took place in medieval times (1455-1487). The House of Lancaster fought against the House of York for control of England. Their war had nothing to do with roses. It wasn’t even named, The War of the Roses, until the 1700s. However, there were roses indirectly involved. King Henry VI (House of Lancaster) had a badge with a red rose on it. Richard, Duke of York, had a badge with a white rose on it. At the end of the war, Henry VII symbolically merged the two sides by creating a red and white rose badge called the Tudor Rose.

The Tudor Rose of the modern day rose war is the Knock Out Rose. This new line of roses is a merger of black spot resistance and beauty. Knock Outs can be found at most garden centers and nurseries. Check them out at http://www.theknockoutrose.com/

Roses that are not resistant to black spot disease are constantly fighting for their lives. Fungicides are required for these susceptible plants. Regularity of spraying and thoroughness of coverage are important. Fungicides protect plants from infection. Once black spot has invaded foliage, fungicide application is of limited value. Susceptible plants must be covered with a protective fungicide at all times during the growing season. Begin spraying new leaves early in the spring. From spring through frost, the plants should never pass through a rainy period without a protective coating of fungicide on the leaves.

Maintenance played a role in the original war of the roses. In the medieval war, the breakdown of royal authority was a major factor. This breakdown was caused by powerful nobles (wealthy English folk) offering protection to followers who would sport their colours and badges (called livery). These nobles also controlled large numbers of paid men-at-arms (called maintenance).

A different type of maintenance plays a key role in the current rose war. Modern day maintenance is a lot safer. A gardener should simply rake and remove diseased leaves in the fall. Diseased canes should also be pruned back to healthy wood. During the growing season, overhead irrigation should be avoided. If you consider yourself a noble, then pay somebody to perform these tasks.

For more black spot info (including a list of fungicides), visit http://www.ces.ncsu.edu/depts/pp/notes/Ornamental/odin002/odin002.htm If you do not have internet access, then call me at 910-893-7533 or email me at gpierce@harnett.org

In the original War of the Roses, the two sides fought under banners not badges. Henry’s banner had a red dragon on it. Richard’s banner had a white boar on it. If historians had named it the war of the dragons and pigs, then instead of the Tudor Rose, the merger would have been called barbecue.

Gary L. Pierce

Horticulture Extension Agent

Harnett County

 
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