Of the named roses I have, first place would be Grootendorst Pink, second running are Rabble Rouser and Cecile Brunner plus from what I seen Knock Out could be in this group. Alexander MacKinzie just fell of the running with a lot of rust. Big black spots and then the rust sets in.
Neil
Photos
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Those big black spots appear to be sun scald, Neil. Rust has never had that symptom here, even on Alexander MacKenzie.
Your right Kim, it’s not rust, just dead spots on the leaves. I hope your not saying AM can get rust. That’s about the only thing I cull for early on.
Neil
ANY rose, under the right conditions, CAN rust, black spot or mildew. AM is half Queen Elizabeth. QE is a great rose, but she is highly susceptible to rust in the right conditions here. Many more cold hardy roses, bred for harsh winters have suffered rust and black spot in my too long, too hot, too water stressed climate. Autumn Damask has rusted and black spotted here. Not that they aren’t great roses, they’re just not climatically suited to MY climate demands.
Along with water and heat stress is the stress of a plant not having the proper nutrition, pH, and a decent enough soil to support its’ flowering and reproductive needs. I have a couple of roses growing into the ‘compost pile’, which is an ongoing work in continuous progress. It is amazing to see how well some of the culls that did not get dumped fast enough recovered and are doing. The compost pile seems to be an instant recovery room for blackspot, even though I do sometimes dump diseased foliage there. The really ‘good’ performers do not need their own compost pile to thrive.
The really good performers don’t need anything special at all.
I do somewhat similar, the culls go to death row till there is time to dump and some perk right up.
A strange transformation sometimes takes place if left for over a year. I’ve had rooted cuttings of my lesser seedlings left to barely survive and at the end of the second year put out a great flower that I don’t recognize. After planting in the ground, the next year they are some of the cleanest.
Neil
Neil,
That doesn’t look like any rust I ever saw.
I have a question: What did you spray on that rose? I wondered whether you might have allowed the plant to get too dry, but the damage really does not look like the result of drought, so I’m wondering whether you have done some foliar feeding or have sprayed something else on the leaves.
Peter
Neil, have you investigated the orange-brown spots in the black patches in those leaves? If it’s rust, you should be able to rub off a rusty powder from their undersides. If there is nothing there, just the orange-brown dead spots, it isn’t rust.
Peter,
I don’t spray and haven’t watered yet. It could be from residual synthetic fertilizer applied during the rain or the sunburn. I just flick the fertilizer, it turned one red flower bright blue in parts as it shriveled up.
I did check closer Kim and realized it wasn’t powdery on the underside.
And thanks everyone.
Neil