kimloveroses
Newly Registered
Posts: 6
Joined: Fri Apr 17, 2015 4:18 pm
Location: SW MO Zone 5

Black Spot

Hello fellow gardeners, I need help. I planted several knock out roses last summer and spring is now upon us and they are leafing out. However they are all covered in black spot! On the canes mostly. The leaves are still healthy, not black spots on them yet. From what I have read I need to remove any part of the rose that has the black spots on them however if I do that I will be left with nothing but a stub sticking out of the ground. The spots are to the base of the roses. Can these roses be saved? Do I need to prune them back to the ground and treat the plant and hope they come back? Thank you for your help

luis_pr
Greener Thumb
Posts: 824
Joined: Sun Jul 05, 2009 8:31 am
Location: Hurst, TX USA Zone 7b/8a

Regarding the " need to remove any part of the rose that has the black spots on them", I would apply that to the leaves only. I would not prune them but when you spray them, make sure you spray all the branches and both sides of a-l-l the leaves (ie, new and still opening leaves plus older ones too). There is just no good way to look at a leaf and know if it has already been infected or not. Maybe if you wear the orange glasses and the blue light flashlights that they use in the CSI TV Programs! Hee hee hee!

kimloveroses
Newly Registered
Posts: 6
Joined: Fri Apr 17, 2015 4:18 pm
Location: SW MO Zone 5

Thank you for your reply. I found some Bayer Rose treatment at the store but it is granules that is added to the soil around the base of the plant. It also treats for bugs and fertilizes. Is this a good option or for black spot should I stick to a spray? I am not sure how a granule will kill the fungus on the leaves.

imafan26
Mod
Posts: 13962
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

The systemic rose care will do a good job on black spot and prevents mildew as well. It does contain imidacloprid so to be good to the bees, disbud for at least a couple of months. If you are using Bayer tree and shrub it will protect for one year. That will give you fewer problems with pests and disease, but will definitely impact the bees.

Some roses are more susceptible to black spot than others. Roses with glossy leaves have fewer problems with both mildew and black spot.

Make sure your roses are spaced so they get good air circulation by planting them far enough apart and pruning to open them up.

When the weather gets humid, it is best to prevent rather than cure fungal problems. You can use a preventive horticultural oil spray, sulfur, or milk spray that will help to coat the leaves and prevent the disease from getting a hold.
You will need to spray regularly.

Remove and destroy any infested leaves as they appear, especially from the ground.



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