Pattie, where are you located?
What sort of weather have you been having?
And are photos possible?

Jeri

Hi, Jeri,

As always, you respond quickly to anxious novice questions. What a gift you are to this board and all the other forums you support.

I am in Novato, (home of the lovely OTN!) about 30 miles north of San Francisco. We had a few 100 degree days two weeks ago, but lately it has been very temperate, in the 80s most days. I will add that, like the rest of CA, we are under water restrictions, so the roses' water supply has been carefully monitored. Is this their way of telling me that they need more? When I went to take photos, I realized that the blotches on the cane are only on one cane that is stretched out horizontally on the fence. Can canes get sunburned?

I'm sorry these photos are so large, but this is my first experience with Photobucket. Honestly, I am simply thrilled that I managed to make it work!

{{gwi:296423}}

{{gwi:296424}}

Thank you so much for your kindness and your help!

Pattie

Hi, Jeri,

As always, you respond quickly to anxious novice questions. What a gift you are to this board and all the other forums you support.

I am in Novato, (home of the lovely OTN!) about 30 miles north of San Francisco. We had a few 100 degree days two weeks ago, but lately it has been very temperate, in the 80s most days. I will add that, like the rest of CA, we are under water restrictions, so the roses' water supply has been carefully monitored. Is this their way of telling me that they need more? When I went to take photos, I realized that the blotches on the cane are only on one cane that is stretched out horizontally on the fence. Can canes get sunburned?

I'm sorry these photos are so large, but this is my first experience with Photobucket. Honestly, I am simply thrilled that I managed to make it work!

{{gwi:296423}}

{{gwi:296424}}

Thank you so much for your kindness and your help!

Pattie

>Can canes get sunburned?

Yes, Ma'am! They surely can!
Pattie, I was thinking maybe downy mildew, but these look burned. The leaf for sure is. Have you sprayed with anything at all?

If it makes you feel any better, I've had damage just like this. It's particularly a problem down on my hillside, which is South-facing. I've absolutely lost roses down there because their canes were burned so extensively.
I'm not even sure more water would prevent it. I do try to hose-wash the roses when the temperatures go up very quickly -- but of course, even that is denied to us by rationing in many places.

Jeri

I have not sprayed anything. I was planning to spray with AACT, but haven't gotten to it. My MACs, SdlM, and several Austins have downy mildew, but the plants with the purple, burned leaves do not. Only a few leaves on three plants are showing this damage, so I'll watch carefully to see if it worsens, improves or spreads.

I think that one cane got sunburned in the heatwave. The rest of the plant looks healthy, and other than the burn, so does the affected cane. Again, I'll watch it. It's funny that last year that same plant was in too much shade so I moved it into a prime, sunny spot and now it's burned. Ah well... rose gardening is a humbling adventure in trial and error!

I use the hose periodically, too, especially when it gets really hot. Then I hold my breath and tremble when the water bill arrives. I am willing to pay the higher rates, but I fear penalties for overusage. sigh. The weather gurus are predicting this will be an El Nino year, so perhaps we won't have to worry next year!

Thanks for your help, Jeri!

Pattie

I agree that this is sunburn on the canes and water stress of the foliage. Hard to avoid when temps get above 95F. Water, water, water, as much as you can afford to.

We're sure praying this is a wet El Nino year.
I'll gladly deal with drowned rose beds and wet dogs, in return for something approaching normal (or over-normal) rainfall.

Jeri

Hi, Patti. That foliage is mighty green. I don't know what fertilizer you're using, but it's risky to fertilize around here in late June, July and early August unless you can provide ample water. If you fertilized heavily in the spring, that fertilizer might be coming into contact with the roots when the rose is dry.

I'd also like to see photos of downy mildew in Novato. A few more weeks at these temps, and the DM will be gone.

I also was going to mention fertilizer as a possible factor, interacting with hot dry air and low soil moisture. Basically, anything soluble in the soil moisture reduces the plant's ability to take up water through osmosis, plus some nutrients are directly toxic in excess.

It is rarely over 90 F here, and my plants usually have ample water. But I used to see exactly that type of foliar damage occasionally. I thought for a while it must be a fungus, but finally decided it was ammonium toxicity from too much fast nitrogen.

Hi, Cass!

I have not used any fertilizer except about 1 cup of alfalfa in April. I was feeling guilty about that and was preparing to do another dose, but now I won't.

The roses I mentioned in the earlier post have powdery mildew. The photo below shows three Austins with what I think is downy mildew. Leaves from top are Incredible Mr. Fairchild, Benjamin Britten and The Alnwick Rose. Between this and the endless rust, nearly all the Austins are on the way out of my garden.

Thanks,
Pattie

{{gwi:296425}}

That looks like what we understand as downy mildew.

But cheer up! Once it gets real hot, that's less of a problem!

Jeri

And I agree. Patti, it's a very odd year to have DM. We had a dry winter and spring, which I wouldn't expect to promote DM. I think I only saw a tiny amount. Give your Austins more of the hot summer to get rid of the DM, assuming they don't have rust. If they rust, off with their heads sooner rather than later.

Oh, Cass is right!
If any of your Austins turn out to be rusters, just prune 'em with a shovel right now, and don't prolong the agony!

Jeri

Cass and Jeri, I'm laughing because I just posted my shovel-pruning plans in the 2010 Rose Plans thread. Most of my Austins have DM, PM and rust, so they are on the way out. Plus, I planted 3 of each in a small triangle per Michael Marriott's instruction, so I will replace each group of 3 sick Austins with 1 healthy tea, china or found rose, thereby saving water in the process. The only sad part is that the grafted Austins are huge and replacements are babies, so in the short-run the garden will look like it's taking a step backwards. But I'd rather have healthy babies than rusty, mildewed big plants any day!

But your definite replies about rust make me wonder: is it contagious? Are the nearby baby teas, chinas and noisettes going to start rusting, too?

Thanks to both of you for sharing all your advice and experience. Cass, I always check your website for rose evaluations before I purchase -- thanks!

Pattie

I don't think it's really contagious -- if the things around it are resistant, they're resistant.
But it really is ugly, isn't it?

One of the worst rusters I've EVER had was the Austin, 'Ambridge Rose.' I'll never forget it, because it was so spectacularly awful. I kept it for 3-4 years, hoping it would improve, but it never did, and in retrospect, I should have shovel-pruned it LONG before I did.

Jeri
(About to head out for a road trip to NW Texas)

Pattie, once a ruster, always a ruster. Rust mean the rose never makes it into the ground. Rust is not curable in our coastal climate.

With PM, some roses will actually outgrow it. Or you'll find the cause is too much or not enough water. Some roses are just susceptible to PM, and they can't be tolerated in my climate.

With bs, it can occur in a the damp spring and at no other time. I rarely worry about it unless I see it off season. BS mid-summer or in the fall means I remove the plant because it's highly susceptible to bs.

DM....is difficult. A young rose that came with DM would never make it to the ground. This year, nothing should really have had DM unless the rose was delivered with it. And that does happen. If the rose is already in the ground and otherwise resistant, I might let it get through the summer and see what it does in October. I've had outbreaks of DM where the roses didn't recover until late summer. But that was during mega-wet winters and springs. We didn't have that this year.

NEXT spring is when we in CA may see downy. If in fact it is a wet El Nino year. But I'll wrestle with that, in return for the groundwater.

Jeri