Elite colleges and universities may prize the English ivy climbing up musty old walls, but in the environment, English ivy is a destructive invader.
All along the George Washington Memorial Parkway, many of the tree trunks and some limbs are covered with ever-climbing, green English ivy. The ivy vines especially stand out in the winter months along the parkway and, for example, in Mount Vernon Park next to the Belle View Boulevard hill just west of Fort Hunt Road. It’s also strangling many trees along Fort Hunt Road and Paul Spring Parkway in the Paul Spring Stream Valley Park.
It’s everywhere year-round and worsens every year if not controlled. English ivy occurs throughout the Eastern United States and many garden shops sell it.
English ivy (Hedera helix) is a perennial, aggressive, non-native, drought-tolerant plant. When it climbs, its aerial rootlets attach to the object it climbs. When it matures, it flowers and sets fruit. Birds eat and disseminate the fruits.
English ivy can cover a tree’s bark and block the sunlight the tree needs for photosynthesis. Ivy vines “that climb up trees slowly kill the tree from the base upwards by enveloping branches and twigs, blocking sunlight, causing branch and eventual tree death,” says Plant Invaders of the Mid-Atlantic Natural Areas. Trees that are weighed down with vines are susceptible to blowing down during rain, snow and ice storms.
When it grows up buildings and walls, it can damage stucco, wood, mortar, siding and shingles. On and around trees, ivy competes for nutrients and water. It can accelerate tree rot by trapping moisture on and close to the tree trunk.
Friends of Dyke Marsh volunteers are tackling the English ivy growing up trees in the Dyke Marsh Wildlife Preserve. They are cutting a 12-to-24-inch “window” in the ivy, pulling vines away from the tree’s base and bagging the plants for disposal so they don’t re-root. Eventually, the remaining ivy will die. Experts recommend pulling up ivy from the ground at least two feet around the tree.
Ivy spreads, carpets the ground and smothers all the native vegetation under it by blocking the sunlight these plants need. Ivy can be hiding places for rodents and is a reservoir for bacterial leaf scorch, a harmful plant pathogen.
For ivy on the ground, some property owners mow it with a lawn mower or string trimmer and cover it with weed cloth or cardboard to starve it of sunlight. It usually takes at least a year to kill the ivy using this method. There are chemical controls as well, but many herbicides can harm valuable plants and insects. Some people use a white vinegar and dish soap mixture. Whatever control method is used, English ivy is persistent and it can return from small roots and stem segments.
To help in Dyke Marsh, email email@example.com and put English ivy in the subject box. The Friends of Dyke Marsh will hold socially-distanced volunteer sessions from 10 a.m. to 12 noon on Jan. 9 and Jan. 18 and Feb. 6 and Feb. 20, 2021. Meet at the Haul Road trail entrance just off the parkway. Park in Belle Haven Park’s south parking lot. Wear a mask and gloves, long pants and sleeves and bring clippers and water.
The Fairfax County Park Authority needs volunteers to help with invasive plants. Visit https://www.fairfaxcounty.gov/parks/resources/ima/.
Tips on controlling English ivy: http://www.earthcorps.org/ftp/ECScience/Projects/Shoreline/Ivy_Herbicide_Study_2012.pdf ; https://hgic.clemson.edu/factsheet/english-ivy-control/
Invasive plants of the Mid-Atlantic: https://www.invasive.org/eastern/midatlantic/.