Page 24—Com Talk, Lancaster Fanning, Saturday, January 24,1
ESTABLISHING
SWITCHGRASS
IN CORN
Greg Roth
And BUI Curran
Department Of Agronomy
Penn State
A couple of years back we
were asked to help out on a
research project evaluating the
potential for converting com
fields to switchgrass.
Switchgrass is a warm sea
son perennial grass that pro
vides excellent cover for pheas
ants. rabbits, and deer. It can
also provide high yields of a
medium quality forage during
the August summer slump in
production of the cool season
grasses.
One problem with switch
grass is that it is slow to estab
lish, with very low yields in the
establishment year. It is diffi
cult to take a year off of produc
tion just to get the crop estab
lished. In addition to the finan
USDA
Corn
WASHINGTON. D.C
Despite a reduction in com
expoit numbers, USDA has
again projected record com use
for this crop year.
The recent USDA
figures project a total
use of 9.415 billion
bushels, 10 million
bushels higher than
the previous annual
use high of 9.40 Wl
lion bushels in
1994-1995.
Exports are down
125 million bushels
from last month’s
estimate, but domes
tic feed use is up 200
million bushels.
Food, seed, and
industrial use is also
up 40 million bushels,
due in part to higher
than expected
demand for ethanol
and high fructose com
syrup.
National Corn
Growers Association
(NCGA) President
Ryland Utlaut said he
is encouraged, opti
mistic, and pleased
with the USDA
numbers.
“This shows there
is excellent demand
domestically for our
crop," said Utlaut,
noting that com grow
ers will continue
dal loss, there is the potential
for weeds to invade during the
establishment year, greatly
reducing the potential success
of the switchgrass.
Several conservation groups
as well as other interest groups
in the state would like to see
more acres of switchgrass
established to improve habitat
and cover for some game spe
cies. used in riparian zones for
soil stability and reduced nutri
ent runoff, as additional sum
mer forage, or as a potential
source for the biofuel industry.
As a result, we have collabor
ated with Penn State researcher
Dr. John Shaffer and USDA
researcher Dr. Ron Schnabel to
evaluate switchgrass establish
ment in com.
Taking ideas from several
farmers in the state who had
tried this approach, we eva
luated various herbicides, plant
populations, hybrids, and nitro
gen rates. Our basic approach
was to no-till switchgrass into
com stubble in late April at a
Projects Record
Use This Year
working to expand this for our commodity. At the same
demand. “Figures showing time we have some woik ahead
higher domestic use than pro- of us in the export arena, espe
duction paints a bright future dally in Asia.”
‘rate of about 13 pounds of
switchgrass seed (pure live
seed or PLS) per acre. In early
May, we no-tilled com into the
field and treated it with a con
ventional Roundup plus 2
quarts per acre Bicep herbicide
program.
In another part of the field we
didn’t plant any com and
instead evaluated a number of
com herbicides for their injury
potential on the emerging
switchgrass. There are a num
ber of effective btoadleaf herbi
cides that provide adequate
safety to switchgrass. There
fore, we were particularly inter
ested in examining herbicides
that control annual grassy
weeds such as foxtail.
Our switchgrass stands in the
com were adequate, but not as
good as expected in the first
year of establishment. Howev
er, on the positive side we were
able to produce silage yields of
about 20 tons per acre with
minimal effect on the com.
None of the com management
factors appeared to have a
major impact on the switch
grass, except our preemergence
herbicide program (Bicep),
which appeared to greatly
reduce our first year switch
grass stand.
Even though our stands were
thin the first year, the switch
grass filled in well during the
second year in both fields we
worked with. Now these fields
are in their second and third
years of production and the
stands are providing excellent
wildlife cover.
This fall a we got our reward
from the project by seeing a fat
doe bound out of the switch
grass on a December afternoon.
We evaluated a number of her
bicides for switchgrass toler
ance including preemergence
applications of atrazine.
Bladex, Princep, Dual, and
Bicep as well as post applica
tions of Accent, Beacon, Basis,
and Pursuit In general, any of
the treatments containing Dual
or any of the post applied herbi
cides reduced the establishment
year switchgrass stand or
growth by at least SO percent.
The three triazines (atrazine.
Bladex, and Princep) caused
little or no injury to the switch
grass. However, as in the com
trial, by the year after establish
ment, switchgrass stands had
greatly improved in all treat
ments, although the best stands
were still in the triazine treat
ments (I believe that some
switchgrass plants recovered
from the herbicide treatment,
and other new plants emerged
later in the season and the fol
lowing year.)
Based on these results, sever
al herbicide programs may be
possible for establishing
switchgrass in com. However,
the safest herbicide program
should be based on the triazine
herbicides. Atrazine plus
Bladex, or Atrazine plus Prin
ted at 2 to 3 ids
(total triazine) per acre should
provide adequate safety for
switchgrass establishment as
well as some grassy weed
control.
Although switchgrass in the
nontriazine treatments
appeared to recover somewhat
by the second year, die reduc
tion in switchgrass stand during
establishment certainly raises
concern about their utility in
this cropping system. Peihaps
increasing the switchgrass
seeding rate or changing other
management inputs might help
the success of other com heibi
cides, but these variables
should first be adequately
tested.
The best advise is to avoid
establishing switchgrass in
fields that had heavy annual
grass populations (foxtail and
panicum) within the previous
two seasons and to use the tria
zines when necessaiy for sup
pression of susceptible weed
species. While switchgrass is a
great wildlife cover, it can be a
challenge to control in no-till
com and soybeans. It is dor
mant in the spring when con
ventional herbicides are
applied and, once established,
tolerates most residual
materials.
So in some of our continuous
no-till com and soybean fields
switchgrass has spread via til
lage and/or harvesting equip
ment has been become a prob
lem. In tilled fields, it is not a
(Turn to Pago 25)