We recently moved into a new home on a canal. The landscaper put down mulch, but a plant called Phragmites, a tall bamboo-like grass, is poking up everywhere. I tried digging the network of roots, but they are 18 inches deep and everywhere. What environmentally friendly potion can I use to kill them? Or are they good natives I should leave alone?
This reedy grass with fluffy seed plumes has confounded scientists. Its explosive population made it seem like a foreign invasive plant, yet phragmites appears in Maryland's ancient fossil layers. Recently, the mystery was solved when Kristin Saltonstall of the University of Maryland Center for Environment and Estuarine Studies, determined from its DNA that there are two types of phragmites. The invasive one is indeed non-native. Native phragmites is now rare, the invasive type having crowded it out on the East Coast except in the Delmarva area.
You probably have the aggressive non-native type, which forms dense stands and emerges earlier in spring. Our native phragmites is the opposite. It also decomposes faster, which means the two types affect the bay very differently. To control phragmites, do not dig. Roots break and re-sprout, spreading the plant. When phragmites is blooming, use a glyphosate herbicide formulated to be safe near water. Paint it on cut stems or spray on foliage. If you cannot use herbicide, cut the plants every year in late July to reduce spread. For an herbicide permit, call Ed Gerther, Maryland Department of the Environment, at 410-537-3651. The permit form is at www.mde.state.md.us / epsc / wmapermit.html. Some counties allow burning of phragmities.
1. Monitor evergreen trees and shrubs, especially spruces, for signs of newly hatched bagworm larvae (you'll see very small bags attached to needles and stems.) Spray with Bt, a microbial insecticide, to control young larvae.
2. Remove spent blossoms to promote vigorous plant growth and continuous flowering.
Jon Traunfeld, regional specialist, and Ellen Nibali, horticulture consultant, work at the University of Maryland Cooperative Extension's Home and Garden Information Center. The center offers Maryland residents free gardening information and answers to plant and pest questions. Call its hot line at 800-342-2507 (Monday through Friday, 8 a.m.-1 p.m.) or e-mail questions to www.hgic.umd.edu. (You can also download or order publications and diagnose plant problems online.)