My roses have black spots on their leaves - is this harmful and what should I do?

Answer 1

It sounds like it could be black spot (really) It is a fungus: Diplocarpon rosea the proper steps to take are:1) Rake and discard all fallen leaves because they are the main source of spores in the spring. 2) Also prune and discard any obviously infected canes. 3) Avoid wetting the foliage especially during dark cloudy days. 3) Grow plants in an open sunny location to promote rapid drying of the foliage. 4) Do not plant in dense plantings and avoid windbreaks to allow good air circulation. 5) Roses vary in their resistance to this disease. Use resistant varieties for low maintenance plantings. 6) Removing infected leaves as they arise early in the season may help to retard the rate of disease spread. 7) Several fungicides are registered for control of black spot Because of the waxy nature of rose leaves, a spreader added to the spray will give better coverage.
If humid conditions are anticipated, spray preventitivly with a fungiced listed for roses. If the infection is severe enough, you nmay have to dig out the rose, discard it and plant a resistant variety. When pruning an infected rose, always disinfect the blades of your pruner between cuts.

Hot and humid weather contribute to this disease. Contact your Local Cooperative Extension office and ask to speak to a Master Gardener. That will be your best source of LOCAL information.

Answer 2

Black spot is the most important infectious disease of roses. It occurs only on roses (Rosa spp.), and is widespread among rose species and cultivars, although some of the shrub roses and rugosa roses show more resistance. Many hybrid tea roses are very susceptible. Lists of black spot-resistance hybrid tea roses often are variable due to localized races of the pathogen.

Diagnostic Symptoms
Round to irregular black splotches with fringed margins are quite obvious, mostly on upper leaf surfaces. Leaf yellowing develops around these black spots, with defoliation of these infected leaves common. Repeated defoliation weakens plants, leading to poorer blooming and greater sensitivity to other stresses. Occasionally symptoms are noted on petals (red dots, distortions), and on petioles, fruit and canes.

Control Hints

Keep foliage dry. Plant roses in sunny locations to encourage drying after rains. Avoid sites with dense surrounding vegetation, so that good air movement will dry leaves. Avoid overhead irrigation, especially late in the day. Black spot is most severe in summers with sustained rainy periods.


Sanitation. Remove all black spotted leaves from and around plants. This should be done throughout the season. Before winter, remove and clean up all diseased leaves and remove diseased canes where possible.


Disease resistance. Listing susceptibility and resistance of all roses would take volumes. In addition, the occurrence of local races of the pathogen often result in a particular cultivar being listed as susceptible in one area and resistant in another. However, some lists have general usefulness; see Table 1. Also, consult local Extension publications and books, consult local rosarians and garden center horticulturists, and make observations of relative disease incidence in local rose collections and your own gardens.

Preventive fungicide applications. Fungicide controls are not successful if cultural and sanitation practices listed above are not followed. For fungicides to work, applications must be made preventively.

Answer 3

When you typed this question, similar questions came up. Why didn't you check them??? This question has been asked and answered several times. If you do a search on "blackspot roses" I'll bet you will find answers!

Yes, it's a fungus. Follow the sanitation directions you were given. Then spray the foliage with a solution of 1 T. baking soda in a gallon of water. Repeat after a rain. Baking soda changes the pH of the leaves, which is all you need.

Answer 4

If the spots look like scabs, then you've got an insect problem. Otherwise it sounds like a mold or fungus. Check out web sites about scale, mold and fungus'. I bet you can save your roses, though.

Answer 5

sounds like blite