"JimS." wrote

Does being near or under a tree make blackspot worse? My Kentucky Derby
is
always COVERED with blackspot, and no amount of anything will keep it from
looking pitiful. The tree is a crabapple, I think. I have 3 other roses
under the same tree (it doesn't block their sun) and they all have minor
blackspot too, though not as much. I wonder if the tree makes it worse?
Or
weeds? Does anyone else have a blackspot problem with Kentucky Derby?

JimS.

Hello Jim,

Are you sure it is blackspot and not cercospora?
The trees in the park around us have a constant strain of cercospora and
naturally everything including our roses are spotted with it. Actually the
two roses under our crabapple Brandywine are clean as whistles. Check this
link for the cercospora info.

http://www.aces.edu/department/extco...5/anr-505.html

Allegra