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Black spot?

Posted by redhighlander 6 (My Page) on
Wed, Jul 3, 13 at 18:04

Beginning rose gardener. We recently moved into this house. I was deadheading a climbing thornless rose, and discovered that the leaves were dropping like crazy. They're pretty yellow and before they turn yellow, they seem to have a few black spots. Is this black spot? Any suggestions what to do now? Thank you!

Follow-Up Postings:

RE: Black spot?

It might be, or some other spot disease. "Drooping like crazy yellow foliage" sounds like the issues are going to be too little water; too much water; too much heat (reflected/radiated/direct); something damaging the roots (gophers, voles, moles loosening the soil interrupting water intake); too heavy or improper fertilizing (done with too little water?); too heavy or improper spraying. Check out the soil moisture, heat levels, soil and root situations first. Adjust what's wrong there before you do anything corrective about potential black spot. If it's as stressed as your description makes it sound to me, anything you do chemically to help it, could severely damage or even kill it. Clear, detailed photos of the specific issues would certainly help eliminate possibilities and aid in diagnosing the problems. Kim

RE: Black spot?

Where are you located? If you are in the East or Midwest, chances are you have black spot.- it is ubiquitous. You may have other problems as well, but whatever they might be, chances are that black spot is high on the list.

Please tell us where you are located and what your growing conditions are. And yes, photos are the next best thing to being there when it comes to diagnosing disease problems.

RE: Black spot?

From your description you do have blackspot. Pick off all the infected leaves and pick up all the fallen leaves. Blackspot will not kill the plant, it will weaken it. Bayer makes a product call Rose Disease Control. If you apply that fungicide as the label says it will keep your leaves clean all year

RE: Black spot?

"Black spot will weaken a rose bush but not kill it." I've read that so many times it is beginning to take on the aspects of a garden myth.

Is it true? Speaking strictly, yes. In practical terms that matter to us as gardeners, no. it is not true.

An uncontrolled black spot infection may significantly weaken a rose bush through a number of actions (defoliation, metabolic reduction, and others). That makes the bush susceptible to other injury, such as from winter damage, drought damage, etc. So the bush dies. Did the black spot kill it? In practical terms, it did.

RE: Black spot?

Yes, being weakened by defoliation can lead to death by other causes. For example, if a rose is trying to grow out during the fall after being defoliated, it may use up most of its stored chemical energy (sugars and starches) in producing this new growth. Then it doesn't have the reserves needed to prepare for winter (it needs sugar for antifreeze) and needed to grow out in spring. So in zone 7a and colder, defoliation from blackspot can lead to the death of rose plants over the winter, especially with hybrid teas and floribundas. However, varieties that are more winter-hardy may survive these conditions for years.

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