Your nursery advice is all wrong. Wet foliage is exactly what allows blackspot spores to germinate and flourish. Research also shows no need to remove the affected foliage, although you will hear that advice all the time. There is no clear evidence that cornmeal will help with BS on roses. There are "soft" methods for control, such as sulfur, the Cornell formula, and others. A search of Gardenweb "Roses" forum archives will provide you with loads of information about this. While a healthy rose will be able to better outgrow disease, a BS susceptible rose will get it no matter what. However, you should be fertilizing your roses throughout the growing season and doing what you can to improve the soil tilth, such as adding compost top dressing. You might consider replacing your roses with more resistant varieties over time if you don't want to deal with controlling diseases. Good luck.

I made an error in my original message. My apologies. Someone else in my household is in charge of the watering, hence my error. The roses are on their own irrigation system and are only watered once a week unless you count the unintentional watering that the neighbor gives them. Thank you JAYK for your advice. You said just what I was afraid of--that it wasn't necessary for me to pull the leaves off the plant. I just spent over an hour reading some of the rose forum thread on chemicals to use on black spot and am still (more?) confused. Do you or anyone else have any advice for the rose bush that I pruned almost all the leaves off of (only about 6 leaves left on it now)? Do I use the neem oil my local nursery suggested (and have already purchased)or do I heed some research I did that shows neem oil can interfere with photosynthesis and wait for more leaves to grow before using neem? Or use something else entirely? A relative says he remembers using something many years ago that went in with the fertilizer in granular form and so didn't need to be sprayed and thus limited the safety precautions which I would certainly appreciate if it works. I didn't see anything about this product in the thread on black spot that I read; maybe it was there and I missed it but most of the discussion seemed to focus on commercial sprays. I'll do so more reading tomorrow and see if I can find a reference to it. I'd very much like to save the bush; it was well-established, planted about 15 years ago. I'd rather not be the one to kill it. Thanks.

I think your best approach at this point is to nourish the roses and keep them well watered. Try alfalfa and kelp. Avoid getting foilage wet, water in the a.m. so foilage that might get wet has a chance to dry. Some people, I'm not one of them, have had good luck using cornmeal to prevent and slow the advance of blackspot. Nandina, a respected member of GW, started a popular thread on the Garden Experiments forum about cornmeal/blackspot. You might want to review that thread.

The Cornell Method of blackspot/mildew prevention calls for fine horticultural oil. I don't know if neem oil would interfere with photosynthesis. Field has some good info on neem oil, organic and non-organic rose growing on his website.

Here is a link that might be useful: Field's site

If you want to go organic, the Cornell spray or wettable sulfur are the way to go. Search the archives and you'll find lots of posts on this. Since you are in CA, where blackspot usually isn't much of a problem, you can probably get good control of the situation this way. I agree with the other posts that your nursery was full of bunk. Stripping leaves is not a good idea and doesn't solve the problem.

If you want a simple fertilizer solution, go with Rosetone.

This time of year, roses usually need more water than just once a week, even on the coast where I am. I would water them at least every other day until you get more leaves.

- HershiGrl

Check to see whether the problem is true black spot. Black spot spots have fine fringy margins. Another spot disease is anthracnose, which makes reddish ring spots with gray or tan centers, and there are others. Where are you located? True black spot is rare in many parts of California.

Water on the foliage causes true black spot to spread only if it is continuously wet for 9-12 hours. So a sprinkle doesn't hurt if the humidity is low.

Rosenewbie, don't worry, new leaves will grow back, I have had many a bush loose all its leaves after digging up the bush in mid summer etc... As long as its well watered, a few weeks or a month later, new leaves will sprout.

I have found some small particles in two pots of roses. Within a day, they died. I didn't place those particles in the pot, but I know they were placed there purposely. What could it be and how can I protect them?