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Last season my climbing rose had a very strong fungal infection, black-spot or something similar. It affected most of the leafs. This spring I have noticed black rings on most of the canes (see pictures). The canes with the rings have none to almost none new growth. Only one cane looks free of these spots and seems to have new growth.

My questions are:

  1. Does it look to you like these canes are affected by a fungal infection or are those marks cold damage or something else?
  2. Should I trim down all those canes with marks?

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Red areas on the stems can be caused by a heavy black spot infection, but also canker. With canker, the spots may be red or tan or dark brown, but usually they're slightly sunken, whereas black spot red areas are slightly raised. Both are caused by different fungal organisms, so using a fungicide that treats for these, if you can find one, might be helpful. Further information here http://homeguides.sfgate.com/red-spots-rose-stems-69588.html

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  • This was the only article I could find as well, Bamboo. Roses are so...prodigious I expected an awful lot more info on the internet. The 'images' were the lamest group ever.
    – stormy
    May 2, 2018 at 6:27

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