Alien Invasion

Garlic Mustard at Cataract Falls. Photo by Marc Evans

Asian bush honeysuckle in bloom. Photo by Carrol Krause

English ivy clings tightly to a tree trunk. Photo by Carrol Krause

May 22, 2010 - HeraldTimesOnline.com 
By Carrol Krause
Herald-Times Homes [email protected]


They’re out there!

Invasive alien plant species are entrenched in the Indiana countryside, reproducing in mind-boggling numbers. And they’re probably growing in your own yard, poised to take over this corner of the planet. Fighting back is the only hope.

Some of the worst offenders were originally planted intentionally, according to Ellen Jacquart, Director of Stewardship for Indiana’s Nature Conservancy.

“Kudzu was planted to help with erosion control, back in the 1930s,” she noted. “It grew so fast that it was billed as ‘the magic bean plant’. It never used to set seed this far north, but with the slightly warmer growing seasons we’ve been having, it’s now starting to produce viable seed. There are five known kudzu locations in Monroe County.”

English ivy and creeping euonymus (commonly called wintercreeper) are widely sold as decorative groundcovers. Neither is native to North America, and both of them run amok here.

“If you want to see how bad creeping euonymus can get,” said Ellen, “go to Dunn Woods. It’s sad to see an area that once had beautiful wildflowers and shrubs be taken over by wintercreeper.”

Asian bush honeysuckle is equally pernicious.

“Go to Cascades Park and look at the Asian bush honeysuckle there,” Ellen advised. “It has pushed out the native ferns, wildflowers and tree seedlings, which are now totally missing from under this canopy of bushes. They not only shade out other plants, but research has shown that bush honeysuckles decrease the growth of mature trees above them by 50% due to their root systems’ more effective capture of nutrients.”

Garlic mustard grows virtually everywhere nowadays. It was originally brought over by German immigrants in the late 1800s as a culinary plant, but escaped. It flowers in late April and early May, then its seedpods ripen, split and drop thousands of seeds, ensuring an exponentially larger crop next year.

Robert Woodling owns more than a hundred acres in northeast Monroe County. He’s a tree farmer, certified by the Forest Stewardship Council (FSC), and does his very best to follow sustainable practices. Beeches and maples grow on certain sections of his property, but on other sections he’s actively encouraging oaks. He has struggled for years with invasives that reduce the number of oak seedlings on his property.

“My biggest headache is Japanese honeysuckle,” Robert acknowledged. “It’s difficult to eradicate. After honeysuckle, the next big one is multiflora rose. They both shade out oak seedlings as well as the natural flora. With the deer situation the way it is, it’s already a problem getting oak to grow; oak is like candy to deer! Deer won’t eat invasives; that makes invasives even more of a problem.”

There is no reliable all-organic herbicide, but Robert uses a relatively benign chemical called Garlon 4 to fight the unwanted species. Although direct application to the bark will kill plants, it’s not particularly toxic to animals or humans.

“For shrubs I spray it around the base of the trunk, 18 inches up,” he explained. “For honeysuckle, I spray each and every tendril. This is my weapon of choice, because I know I’m only killing what I spray it on. None of this happens overnight. It takes about three years to make a dent. Every year you have to do maintenance, and slowly the problems decrease.”

Each time he patrols his woods, he carries a backpack sprayer. For short trips he carries a spray bottle loaded with Garlon 4. On occasion he will also use Glyphosphate 5.

“I work very hard to clear my 100 acres, but neighbors aren’t doing anything, so I can’t rest,” he said. “There is a group of people whose management philosophy is ‘leave it alone, nature will take care of itself.’ That was true back when Indiana was covered with forest, but it’s not true today. If you purchase land and do nothing, you’ll not notice degradation before it’s too late.”

Inside Bloomington, less than half a mile from the courthouse square, historic home owner Marion Sinclair has been waging her own battles against invasives. Over the years her yard has become increasingly overrun with invaders that are smothering the native wildflowers.

“I have English ivy that I planted years ago!” she admitted ruefully. “I planted things before I knew about invasives. This whole bed over here is euonymus that crept over from the neighbors’. Ivy and wintercreeper are bad enough when they’re just ground vines, but they’ll both reproduce with berries if you let them climb trees.”

She also has a problematic privet hedge. “It’s not native. It seeds itself and tends to ‘walk’ out into the yard from the border. I have Asian bush honeysuckle and vining Japanese honeysuckle. My advice: keep up the fight! It’s hard work. I fear for our native plants, some of which are very vulnerable.” She, too, uses Garlon 4 against her invasives.

It’s a wearysome battle, fighting plants in your own yard, especially if your neighbors don’t care and allow the same invasives free rein. Homeowners need to learn to identify and eliminate them properly. Wintercreeper and ivy vines can be pulled up by the roots right after a hard rain has softened the soil. Don’t bother when the ground is hard and dry; the vines will break, leaving the roots to sprout again.

Ellen Jacquart urges everyone to join in the battle against invasives. She recommends Purdue’s Cooperative Agricultural Pest Survey web page, http://extension.entm.purdue.edu/CAPS/ for information on invasive species in Indiana, and bugwood.org for identification and control information on invasive plants.

“Be sure to attend the Farmers’ Market this morning!” she finished, “because at 10:00 there’ll be a native tree planting at 6th and the B-Line Trail, and MC-IRIS will be giving away native tree seedlings at the Farmers’ Market.” MC-IRIS is short for Monroe County - Identify and Reduce Invasive Species, a group of concerned citizens seeking to decrease the impacts of invasive species in Monroe County. To learn more or join, email Ellen Jacquart at e[email protected]. Also find ‘MC-IRIS’ on Facebook.