I don't have blackspot issues but it occurs to me that in a climate such as yours roses with morning sun and afternoon shade would be less stressed and therefore would have more resistance to disease. People with more local knowledge can obviously give you more practical input.

Ingrid

It is probably because morning sun tends to dry the leaves earlier and those with morning shade keep damp leaves longer which encourages blackspot growth. Many roses in the high heat areas of the Southeast seem to welcome a little afternoon shade.
Enjoy your roses!

It might also have to do with how much airflow is available. Perhaps the ones with BS problems are a little too crowded? Just a thought.

Kate

I think it has a lot more to do with the rose selection and the air flow, rather than the time of day the rose is getting exposed to the sun. Morning sun vs. afternoon sun vs. full sun has no correlation to blackspot in my own garden. Right now, here are some examples that I can readily think of:

1. Roses getting full morning sun and afternoon shade that have LOTS of blackspot (example: Pink Gruss an Aachen)
2. Roses getting full morning sun and afternoon shade that have NO blackspot (example: Duchesse de Brabant) or VERY LITTLE blackspot (Heritage)
3. Roses getting no morning sun and full afternoon sun with NO blackspot (example: Reine des Violettes, Mrs Dudley Cross, & Nur Mahal)
4. Roses getting no morning sun and full afternoon sun with LOTS of blackspot (example: Rise-N-Shine)
5. Roses with all day sun with LOTS of blackspot (example: Pink Gruss an Aachen)
6. Roses with all day sun with NO blackspot (example: Thomas Affleck & Valentine)
7. Roses getting mid-day sun only with NO blackspot (example: Basye's Blueberry)
8. Roses getting mid-day sun with quite a LOT of blackspot (Pink Gruss an Aachen)

Randy

I haven't noticed that, but i have had rain,rain,rain, here and haven't seen any bs, i guess the rain keeps the spores either washed off the leaves or out of the air and back to the ground. It probably has more to do with how resistant a rose is, if it's over 85 degrees, i've even noticed less on roses growing in heavy grass/weeds.

I my experance, I do not think it is if the rose gets just morning or just afternoon sun. I have had black spot problems with my roses no matter what when they are exposed to the sun. This year I attacked black spot early by spraying every 7 days and right now (knock on wood) I am keeing it in check by spraying with a natural produce every 14 days. I truly think it has to do more with the rose and if they are under stress. Last year I had major problems but we were in a drought, this year we have had a lot of rain and cooler temps. July and Aug will be the real test in my area.

I have noticed this more with powdery mildew, those with more shade get more mildew (those that are susceptible)

Thank you for all the thoughtful responses.

Blackspot is a problem here. Has been anyway, but I've gotten rid of nearly all the most susceptible. The only thing I have left that's prone in a bad way is SDLM. That may have to go, too, one day.

But there is so much contradictory stuff about blackspot floating around the internet. One site says to hose off the leaves. Another says don't do that because it splashes the spores around. One site says to pick off the infected leaves from the plant and the ground. Another site says that it won't make any difference. Who to believe?

Thanks again.

bellegallica,i hear the contradictions! i don't do anything, and here it doesn't make a difference.

Randy, I don't like to hear that about Pink Gruss an Aachen. I'd really prefer that we just not talk about it. But I must say, after completely defoliating earlier this spring, mine do not have THAT problem at the moment. But at least your comments will keep me from worrying about placement.

Sherry

Morning shade and afternoon sun does not generally make for happy roses in the humid south, especially Florida. Both Paul Zimmerman from Ashdown Roses, and Mike Shoupe from The Antique Rose Emporium do not advise planting roses in full morning shade/afternoon only sun. Both have stated to me that they have never seen a rose truly healthy and happy in that situation, and that has been my experience as well. The only roses that I've had in that situation that do O.K. are the original Knockouts, although they do much better in full sun.

Both my roses and I are much happier now that I gave up on the shade thing. They are all either in full sun all day long, or are getting full sun all day until late afternoon. This has made a HUGE difference. They are well spaced, and I don't spray, including the few hybrid teas I have. I don't keep any roses that can't stay healthy (not necessarily perfect, but robust and healthy), with good soil, good sun, and good air circulation.

Sandy

Sandy, it's probably because it is not as humid here as it is in Florida, but my tea roses that are growing in morning shade and afternoon sun are wildly healthy. Even my hybrid musk growing in those sun conditions is very healthy.

Hi, Sherry. I'm sorry to give you that report on Pink Gruss an Aachen. It's not really so much of a "blackspot" issue as it is a "yellow leaf drop" issue for PGaA. Not really ugly foliage, more of just a lack of foliage at times. BUT ... this is typical of my Pink Gruss roses here. They go through a few cycles during the year of that leaf drop, then, the next thing I know they are beautifully leafed out again. Overall, I love the rose, imperfections and all, and I don't try to compare its blackspot resistance to a china rose, which would be unfair to PGaA in this china-paradise climate of mine. Even though my PGaA's do lose some leaves at times during the year, its leaves are never as "eaten up" with true blackspot as, say, Paul Neyron.

Randy

Thanks, Randy, for the clarification. I've noticed that about PGaA and GaA. I was thinking it was because they're very young, but I guess not. I'm going to try keeping them very well fed and see how that works.

Sherry

Randy, I'm jealous that you can grow roses in morning shade and afternoon sun with no problems! I've had to put three Knockouts as a foundation planting with that exposure for some color, because they seem to do well in that spot. My husband really likes them, and had actually requested them for outside his "home office" window. I, however, would have liked an OGR, although I have to admit they are pretty there.

Since the roses I wanted on the rest of the west side weren't all that happy there, it has given me an opportunity to explore some native plants that don't mind the morning shade and harsh afternoon sun. (I didn't want all Knockouts). I have to admit, the combination is very, very nice. So...it's been a blessing in disguise.

What hybrid musk are you growing in the morning shade/afternoon sun? Is it Nur Mahal, or do you have others?

Sandy