Pests & Diseases
Monday, July 27th, 2009
We are excited about weevils at the Scott Arboretum. The stem-boring weevil, Rhinoncomimus latipes, has been found throughout the Arboretum nibbling on the invasive mile-a-minute weed, Polygonum perfoliatum.
Mile-a-minute weed is an annual Asian vine that has invaded habitats in the northeastern US: forested floodplains, streamside herbaceous wetlands, and upland forests. It can be found growing along the Crum Creek, in the Crum Woods, and on banks throughout the campus.
This prickly, branching vine germinates in April in the Mid-Atlantic region and proceeds to rapidly climb over other plants. It produces iridescent blue berry-like achenes in the beginning of mid-summer, completing its…
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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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