Pests & Diseases
Wednesday, July 15th, 2009
If you have visited the Dean Bond Rose Garden this growing season, you may have noticed a large section of the climbing and hybrid tea beds now contains marigolds, Tagetes patula cultivars, instead of roses. This April we removed about 17 rose shrubs because they were infected with Rose Rosette Disease (RRD).
RRD was first observed by a local gardener and Scott Associate, Judy Penney, on her climbing rose in Swarthmore. The disease has since devastated her once prolific rose and symptoms have begun to appear in the Dean Bond Rose Garden.
On the left a healthy branch of a rose bush…
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Friday, June 26th, 2009
This month you may have noticed shriveling of some stems on your clematis, while others of us have been so unlucky as to experience a dramatic demise of the entire plant shriveling and turning black in a week. These symptoms are typical of a disease called clematis wilt.
Cause
These dramatic symptoms most often manifest just as the plant is about to flower, typically striking the flower buds and new growth first. In my research, I have found 2 fungi credited with causing this theatrical demise, Phoma clematidina and Ascochyta clematidina. These pathogens enter the vine’s vascular system and clog the fluid-carrying…
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Thursday, April 9th, 2009
Now is a good time of year to scout your trees and shrubs for insects because there is no foliage present to hide insects living on the stems or branches. An insect not known to survive Pennsylvania winters, except for the Philadelphia region, is Indian wax scale, Ceroplastes ceriferus. Bill Costello, IPM coordinator, has been seeing these insects on Callicapra and cherry laurel in the John W. Nason Garden for the past three years. For the first time this year, he found them on Japanese maples outside of the Harry Wood Garden.
Indian Wax Scale on the stem of cherry laurel.…
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