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Diggin' In: Battling bamboo

March 17, 2014

NEWPORT NEWS, Va. ó If there is an expert on runaway bamboo, it has to be Dorothy Geyer, a natural resource specialist with the Colonial National Historical Park in Virginiaís Yorktown and Jamestown.

Dorothy spends a great deal of her work time evaluating and managing invasive species, including golden bamboo, a runner grass known scientifically as Phyllostachys aurea, that has claimed 23 acres of land in those two park areas. 

"All of it probably came from someone planting it in their backyard, with the exception of the Glasshouse at Jamestown," Dorothy says.  

"We think that at the Glasshouse someone may have misidentified the bamboo for native canebrake and planted it as a screen. There is some secondary documentation that said it was planted in that area. But we donít have much beyond that."

What Dorothy does know is how aggressively the bamboo has spread in those areas ó the 2.3 acres on the Colonial park/Yorktown Victory in 1999 turned into more than 5 acres by 2011, while 1.2 acres at the Yorktown Battlefield has become 3.3 acres in the same timeframe. Aerial imagery that maps the stands shows smaller, slower growth at the Glasshouse at Jamestown.

To deter more growth, the park service works to eliminate the bamboo, having cut and chemically treated 8 acres so far.  Dorothy says she has read of no biological controls for bamboo.

To best control bamboo, Dorothy suggests getting it while itís small ó stalks no bigger than an inch in diameter.  Cut the bamboo and spray the stump tops with a glyphosate product that has a sticking agent in it.

"Cutting and stump spraying is a good winter activity," Dorothy says.

"I try to go out on a sunny day in the 50s temp to get this work done. This is mostly for human comfort."

Bigger, bolder bamboo demands heavier equipment and effort, she says. Depending on the type of bamboo you have, you need a chain saw, weed whip or weed whacker, Swedish brush axe, pruning snips or other tool that cut through bamboo stems. Hand-held pruning snips work fine for the thinner stemmed running bamboos (Psuedosasa), but it is more labor intensive and time consuming. Cut down as low as is comfortable and leave the remains alone for the summer, allowing it to regrow. In October or early November, on a sunny, no-breeze day, spray the leaves of regrown plants with a 2 percent rate of glyphosate ó   Accord or Roundup Pro ó   mixed with water, according to the label directions ó Dorothy says the 3 percent rate has worked best for her. Apply thoroughly, just to the point of drip.

"Usually this is when I stop for the season," she says.

"However, the Glasshouse location had some very mature bamboo, and there is more re-sprouting going on here, so I am going to try a second spray schedule."

That schedule includes:  Wait 10-14 days and reapply the glyphosate at the same rate. After the second treatment, leave the bamboo alone. Do not cut, mow, or remove plant material. The following spring, the bamboo will be browned out and should not grow back. At this point, you can cut and remove the dead vegetation. If any bamboo remains or does reappear, repeat the procedure.  Learn more about this process at www.nps.gov/plants/alien/pubs/midatlantic/control-grassesandsedges.htm.

"Many manuals say a continuous mowing of the shoots prevents their spread," says Dorothy.

"That is somewhat true, but if you back off the manual cutting, they shoot out quickly. The root tips are amazingly strong and look like little spears. Bamboo has been recorded to grow as much as 10 feet a year in some places. I havenít seen that here, but Iíve seen at least five feet."

If you donít have bamboo in your yard, donít plant it, advises Dorothy. The unruly species she deals with is a runner kind that spreads by underground rhizomes. There are better-behaving clumping types, but when you deal with a bad batch of bamboo, you are usually scarred forever.

"Bamboo has been known to completely take over driveways, concrete pads, etc.," says Dorothy.

"No one ever thinks this stuff will spread until they plant it. This species, as I read the literature, seems to be the most invasive in the Southeast. It is on Invasive.org as a rapid runner. I have found roots that go under and through heavily compacted trails and come out through filter fabric.  

"I wonít suggest any varieties as an alternate because I donít trust the genus, but I have been told that black bamboo isnít bad. But then what happens when the climate changes?  

"My recommendation is to stick with the native canebrake, also known as switch cane, or Arundinaria tecta. It grows thick and tall like bamboo but does not spread at the rate that bamboo does. We have a lot of it in the park and by the Glasshouse site where bamboo got a hold."

In Smithfield, Va., plant collector Linda Pinkham agrees the average gardener should not plant bamboo in the ground ó but possibly in pots that can contain it.

"We love bamboo," says Linda, including landscape designer-husband Bill.

"We have two kinds of bamboo in the ground ó each actually planted in a kiddy pool with the edge exposed so we can see when it tries to jump over the edge. One is an unknown that has yellow vertical stripes on the stems and the other a named cultivar of the black stem bamboo called Black Jade.

"We also have two kinds in pots so they wonít spread. The Sasa veitchii is lovely ó the edges of the leaves turn brown in the winter ó a highly prized dwarf form in Japan.

While most bamboo planters have good intentions of keeping things under control, itís not as easy as you think, warns Linda.

"Even keeping it contained in a kiddy pool can be a little tricky," she says.

"If our big striped one has the edge covered with mulch around the edge, the bamboo shoots jump over in the spring and start growing outside the pool likely crazy. Most gardeners donít want that kind maintenance.

"We have also seen landscapes where bamboo has gotten loose and taken over. It can cause feuds between neighbors   ó one letting it go and the other trying to keep it off their property.

"It is the kind of plant to be used very thoughtfully ó  if at all."

Better-behaving bamboos

Black bamboo, a slower-spreading running bamboo, is used and sold cautiously.

"We sell black bamboo ó Phyllostachys nigra ó which is the only running bamboo that we offer," says Bill Kidd, vice president of merchandising at McDonald Garden Center in Hampton, Va.

"This one is slower to spread and we make sure customers are aware that it is a runner. When choosing a running type itís important to consider installing a barrier to keep the roots from spreading out past where you want them. My neighborís son planted bamboo 20 years ago in her wooded area and we still have to work to control it, so use running only if the correct preparations are made or if you are willing to work to control on a regular basis."

Eric Bailey, a Yorktown landscape designer, likes black bamboo ó but only in containers because it runs.

Clump-forming bamboos are marketed as safer bamboos, but even those depend on where they are planted and how they are planted.

"A few years ago, I spoke to a bamboo grower about clump-forming bamboos ó and he laughed and said there was no such thing ó they just grow slower," says Eric.

Monrovia, a brand name of plants sold extensively at local garden centers and nationwide, markets several new clump-forming bamboos, including Golden Goddess and Sunset Glow.

Nicholas Staddon, director of new plant introductions for Monrovia ó www.monrovia.com ó likes bamboo because itís a sustainable crop, and provides material to craft garden stakes, trellises and fences. Also, fresh bamboo tips can be used in stir-fry dishes, he says.

Clump-forming bamboo is a far cry from the running type, he maintains.

"In the Pacific Northwest, I saw a 15-year-old clump with a 15-foot-high canopy and a clump that was 3-feet wide," he says.

If you fear bamboo, by all means plant it in a container, he says. Bamboo planted in the ground can be safeguarded with a rhizome barrier such as the ones featured and sold by Bamboo Garden at www.bamboogarden.com.

His favorite use of bamboo is a restaurant owner who plants it in wheeled carts that can be quickly arranged to create screening for large-party patrons. This same concept could be used around a home patio.

"It creates an instant room and instant privacy," he says.

 

 


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