What can I do to get rid of black spot disease in my little bed of shrub roses? I sprayed it early in June with a product that Suburban Gardens suggested but it still got progressively worse. We moved to Olathe from Iowa last July & the rose bed was already in place, some large, most small. They bloomed profusely last summer and (so far) this summer. A few have lost most all their leaves at this point.
My concern is not so much for this year as not having to deal with black spot next year. Should I just pitch the bushes that are worst?
Thanks....
Black spot is the most common disease on some types of roses mostly the old fashion hybrid tea types. Many of the new shrub roses such as the widely popular Knock Out are less prone to the disease and flower all summer. Of course you do not get big showy flowers, more small and lower petal count blooms.
Control of black spot is done by regular, weekly or so sprayings throughout the growing season. This is a lot of work, but if you want these types of roses then spray. If not remove and replant. I have attached a K-Stat Fact Sheet on black spot.
Black Spot on Roses
Another option is to plant with the newer so called shrub roses that flower and do not get the diseases. In fact we are promoting a whole group of roses called Earth Kind. These flower all summer long and need little or no care. We are holding a day long workshop this fall. For more information:
Earth Kind Rose Symposium
Best of luck - you will need to decide what is best for you. For me it is only the easy care roses in my garden.
Dennis - Johnson County Extension