Getting Rid of
Japanese Barberry: Why and How
Japanese barberry,
(Berberis thunbergi), arrives in the woods by birds eating the fruits in winter
and pooping/planting them. It can grow in full shade and established woods.
Nobody, (especially not deer), eats the leaves or the prickly twigs. It can
root where branches touch the ground and where seeds are dropped in place to
make eventually an extensive, dense cluster. Its leaves break down quickly and
raise the nitrogen level in the soil, encouraging earthworms and discouraging
native woods plants. It offers mice shelter from predators, encouraging them to
congregate and share germs. Its dense foliage keeps the area underneath it
moist so that ticks can be active almost all the time.
Research by Tom
Worthley, ( University of Connecticut Dept of Extension in College of
Agriculture & Natural Resource), Scott Williams, ( University of
Connecticut Dept of Natural Resources & Environment), and Jeffrey Ward
(Connecticut Agriculture Experiment Station Dept of Forestry & Horticulture),
found:
o 120 Lyme infected
ticks per acre where barberry was “not contained”
o 40 Lyme infected
ticks per acre where barberry was “contained”
o 10 Lyme infected
ticks per acre where barberry was absent
I’ve often said that we
can work with snow on the ground. Snow actually insulates the ground and keeps
it from freezing; it also increases contrast and helps you spot the small
barberry sprouts. But we can’t work when the ground is frozen. Last year I had
to cancel half the work sessions I’d scheduled because of frozen ground: you
just can’t pull plants from frozen ground. The tops just break off and leave
the crown of the plant behind, which leaves it alive and harder to pull the
next time you try. Other years only one or two scheduled workdays have had to
be cancelled: we really don’t get a lot of ground freezing around here,
especially not in the woods with a good layer of leaf litter. The barberry at
Fraser is not found in bare ground locations where the ground would freeze more
readily.
Barberry is what Alan,
(Alan Ford, Potowmack Chapter President), calls a “crown plant:” you kill it by
removing the junction between the topgrowth and the roots. Often it’s easiest
and causes less soil disturbance if you clip the roots and just remove the
crown. It does not grow back from bits of root left in the ground. It does grow
from seeds dropped under larger plants, so that it is very worthwhile to return
to places where there were large plants or patches to pull sprouts until the
seed bank is exhausted — I don’t have statistics on this, but most of them are
gone after 3 years of sprout-pulling.
Margaret Chatham
Potowmack Chapter Newsletter Editor
Potowmack Chapter Newsletter Editor
Read the Potowmack
Chapter Newsletter, which includes information about helping to remove barberry
this winter at Fraser: Potowmack News