Friday, Sept. 10, 2004 – 3:13 p.m.
After weeding this past weekend, much of the bed by the fence was left without mulch. Between the weeds and the natural decomposition of the old mulch (pinestraw), things were pretty much back at bare soil. So yesterday I went and bought 8 bags of pine bark at Lowes. This morning early, I went out to apply some of it. I got several bags down around the roses at one end of the bed (Fragrant Cloud, JFK, Mr. Lincoln, and Madame Berkley) and started looking at the bushes themselves and their spotted leaves. Once a leaf shows spots, that leave is going to die; there is not “healing” from blackspot. Therefore you work to keep existing leaves from getting infected.
There are basically 4 things you do to deal with blackspot on roses:
- Grow disease-resistant varieties.
- Keep the leaves dry. This is done by minimizing overhead watering, particularly in the evening, and planting bushes such that they get good air movement around and through them (to dry the leaves).
- Remove diseased leaves from bushes, including those that fall off and gather around the bush.
- Spray with fungicide.
At this point, I can’t really do anything about #1 and #2 and #4 is being done. That leaves #3 (Sanitation). So, using one of the empty bags from the mulch, I went around and pulled leaves off a the bushes in the bed next to the fence and picked up leaves that had fallen around the bushes. Since the leaves were diseased, I wanted to truly dispose of them rather than compost them. They say that a good working compost pile will destroy the spores… but why take chances? After all, they will winter in the mulch (which is one of the reasons for pulling out and replacing the mulch every spring). I will confess, I could not bring myself to pull off ALL the leaves that show blackspot… but I did the worst of them. Nor did I get to all the beds; The only one I got through completely was the bed by the fence. For the other beds, I basically went through and grabbed the obviously diseased leaves.
Still, it should help…