In an unmanaged tangle of weeds, a year-old pine tree just isn’t
the big guy out there. And all those weeds can add years to the
time it takes a pine to become the towering tree people want.

So within the first year after planting, foresters recommend
spraying a herbicide to knock back the weeds and give the pines
the chance to rise above the crowd.

Herbicides have long been used to control hardwoods in pine
forests, said David Dickens. And for a number of years now, an
early, once-over spray to control smaller weeds has become a
standard management practice.

Worth the Extra Cost

“It’s particularly useful here in the South,” Dickens said,
“where we get such lush vegetative growth. We’ve found it can
enhance growth enough to warrant the additional expense.”

Does the added use of herbicide pose an added threat to people
and wildlife?

Not really, Dickens said.

“In general, the herbicides we use now are very safe, to the
environment and to ourselves, if we take care when we handle and
use them,” he said. “And we use them only once or twice in the
life of the forest, which may be 20-30 years or more.”

Use Herbicide Early

Foresters often recommend using a herbicide to control herbaceous
weeds either in preparing the planting site or within the first
year after planting.

Then within three to five years, they may recommend another
application to control the hardwoods that compete, as the weeds
did earlier, for the moisture and nutrients in the soil.

Later on, as the trees get tall enough, foresters use fire to
control the competing vegetation. Each practice is geared to
giving the pines an edge over the other plants.

Herbicides are simply a management tool in forestry, Dickens
said. And how much management a forest needs depends on what the
landowner wants to do with his land.

Management Extremes

“At one extreme is a highly managed forest with heavy
applications of fertilizer, pesticides and herbicides so there’s
nothing out there growing but pine trees,” he said.

“We do that on some research plots, but it’s often not economical
in general use,” he said. “At the other extreme is an unmanaged,
green jungle. What you generally want is somewhere in-between
those extremes.”

Giving pines an edge but allowing some hardwoods and other plants
in a forest is not only cost-effective, Dickens said, but can
also open the forest to more wildlife species and other
benefits.

Managing toward either extreme would narrow the range of wildlife
that would find the forest attractive. “If you manage the forest
just for one wildlife species such as the spotted owl or red
cockaded woodpecker,” Dickens said, “you manage to hurt other
species.”