When to start treating for blackspot?

davidchance(7a)March 7, 2012

Sorry for the beginner question.

The weather here in NJ has been really warm this winter, and most of my roses are already starting to leaf slightly.

Last summer some of my roses got blackspot and I was way to late to respond to it so by late summer they were nearly 3/4 bare canes.

So when would be a good time to start spraying?

Thank you for reporting this comment. Undo
michaelg(7a NC Mts)

Disease can spread as soon as leaves have expanded. Blackspot germinates when leaves are wet continuously for 8-12 hours with temperatures staying between 60 and 78. I am not sure whether it germinates with temps in the 50s, but, if so, it probably requires longer wetting. So what you want to watch for is mild, humid, drizzly days. It will be too cool at night for a while. With the Bayer tebuconazole fungicide, you can spray up to a week after germination and still stop the infection.

    Bookmark   March 7, 2012 at 1:36PM
Sign Up to comment
More Discussions
Speckled canes?
Hi all, I was out looking at all the lovely new growth...
Dinglehopp3r z7A. EastTN
Double Grafted Rose Bush
I just bought two at my local Lowes ($12.95) but I...
kublakan
Mrs. B. R. Cant
Here are some cuttings of MBRC I started in November,...
thahalibut
Tons of bugs on newly planted roses
So it's been alittle over 2 weeks now and I'm noticing...
bruin27
Fire ants. Friend or foe?
I have fire ants here and there, but they seem to be...
jkellydallas
© 2015 Houzz Inc. Houzz® The new way to design your home™