Is this Black Spot?

Yorky · Rowan Tree Joined: 17 Apr 2007 Posts: 148

If so, can it be treated organically? I've read that a 1:1 ratio of milk and water can be sprayed . Would this be suitable for the stem with no foliage in the picture? How often should I spray?

There are several bushes in the bed and most are affected to varying degrees, the worst being the heavily spotted stem.

http://i238.photobucket.com/albums/ff250/Kilnadrain/P1050254.jpg
http://i238.photobucket.com/albums/ff250/Kilnadrain/P1050256.jpg
http://i238.photobucket.com/albums/ff250/Kilnadrain/P1050257.jpg

Belfast · Ash Tree Joined: 23 Apr 2009 Posts: 243 Location: CSA

try here
Blackspot on roses (Diplocarpon rosae)
http://www.gardenplansireland.com/forum/about1595.html

Liparis · Posted: Sun May 17, 2009 9:04 pm Post subject:

Chimney soot. Not easy to get now. Chimney sweeps used to leave the soot in a heap in your garden after cleaning your chimney, you spread it in the rose-bed. With the advent of smokless zones, blackspot on roses became rife.
Bill.

michael brenock · Posted: Mon May 18, 2009 10:23 am Post subject:

the nitrous compounds present in soot killed off the spores of the overwintered black spot on dead leaves on ground or at least reduced the numbers and viability of the spores. it helps to rake off the dead leaves under the bushes in winter and early spring as this reduces the sources of infection. Follow this with a mulch of garden compost and the extra feed with the smothering effect of the mulch will go a long way to reduce black spot. varieties vary in their resistance to black spot.
michael brenock horticultural advisor (retired)