Friday, February 3, 2012

How to prevent blackspot on roses from coming back?

I have a climbing yellow rose bush, I believe it was called "Golden Showers", that I have had for almost 4 years. Last year it got blackspot. It is starting to fill in again with leaves %26amp; it looks like the spots are gone. All the leaves seem to be free of any blemishes. How do I prevent it from coming back again before it starts. According to the USDA map I live in Zone 6.

How to prevent blackspot on roses from coming back?
As with most fungi, this fungus requires free water for infection to occur. The spores must be wet for at least 7 hours before they can germinate. A temperature of 65 degrees F is best for spore germination and the disease develops most rapidly at about 75oF. Temperatures of 85oF and above inhibit the spread of the disease



Following are some great tips (found at http://www.ehow.com/how_9358_control-bla... that will help you prevent another BLACKSPOT outbreak on your roses;



1) Look for black spot on the leaves of rose plants. This fungus disease will appear as round, black spots ringed by yellow tissue.



2) Water roses only from below. Try not to get the foliage wet when you water.



3) Water in the early morning hours so the rose plant has time to dry during the day.



4) Rake up any fallen leaves from the soil surrounding the plant. Black spot as well as other fungus diseases are transmitted by water splashing back up onto the leaves and stems.



5) Remove any diseased leaves. Pick off and destroy any foliage that has evidence of black spot. Dispose of infected foliage in a sealed plastic bag.



6) Dust roses infected with black spot with sulfur powder. Sulfur will not kill the fungus spores, but it will prevent a new generation from germinating.



7) Spray a solution of 1 tsp. baking soda mixed in 1 qt. warm water in the early morning hours.



8) Spray roses with a dormant oil or Bordeaux mixture when plants are dormant (usually in winter).



FYI: There are a couple of good fungicides found at your local hardware store that will control Blackspot once it appears but I'd recommend that you begin treatments early; "Bayer Advanced Disease Control" or "Daconil". It's been my experience that fungicides haven't been that effective in controlling this disease. If possible, spray ever 7 to 10 days but try to use an alternate fungicide every 3rd spray to avoid resistance to the chemical itself.



Good luck and hope this information was helpful to you!



-Certified Professional Crop Advisor with over 30 years of experience and a Degree in Plant Science
Reply:I'll bet it's a beautiful rose. Start your controls next month. http://www.ag.auburn.edu/aaes/communicat...


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