DEALING WITH BLACK SPOT #171454 - Ask Extension

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DEALING WITH BLACK SPOT #171454

Asked March 25, 2014, 10:34 AM EDT

WHAT IS THE BEST METHOD OF DEALING WITH BLACK SPOT ON MY ROSES? I SEE A FEW INFECTED LEAVES THEN ALMOST OVERNIGHT MY DOZEN ROSE BUSHES ARE TOTALLY ENGULFED. IS THERE SOMETHING THAT IS ENVIRONMENTALLY FRIENDLY? I WAS ONCE TOLD DILUTED AMMONIA WATER WOULD HELP

Harris County Texas

Expert Response

Good sanitation is extremely important when dealing with this fungus. All leaves that have fallen should be cleaned up and disposed of in the garbage. You need to apply a fungicide containing triforine (Funginex), and you will need to apply every 7-10 days in order to protect the leaves that aren't infected.  Good air circulation also is important.

If you are battling black spot year in and year out you may want to consider growing EarthKind roses that have been tested for black spot resistance.
http://aggie-horticulture.tamu.edu/earthkindroses/

Additional resources:
http://www.extension.umn.edu/distribution/horticulture/DG1163.html

http://aggie-horticulture.tamu.edu/archives/parsons/trees/rose.html

Thanks for the question.
Paul Winski Replied March 27, 2014, 4:16 PM EDT

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