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Project Leader: Russell R. Hahn,
Department of Crop & Soil Sciences
Cooperators: None
Type of Grant: Cultural methods;
sanitation; physical controls
Project locations: Findings might
be applied throughout the Northeast
Abstract:
A field experiment was established April 30,
2001 at Caldwell Field, Tompkins County, NY to determine the value of
using recommended and double seeding rates of timothy or orchardgrass
for suppression of roughstalk bluegrass (Poa trivialis L.) in
alfalfa/timothy and alfalfa/orchardgrass seedings. No data on treatment
effectiveness was collected in 2001 since the bluegrass was not present
during the establishment year. Bluegrass did invade the plot area in
the fall of 2001. The plots were harvested four times in 2002 and three
times in 2003. Total forage yields and the percent of the botanical
components (alfalfa, timothy or orchardgrass, bluegrass, and other weeds)
were determined for each harvest date. In the alfalfa check plots, roughstalk
bluegrass was responsible for 46, 12, 3, and 5% of the total forage
yield for the first, second, third, and fourth cuttings respectively
in 2002 and for 30, 18, and 13% of the total forage yield for the first,
second, and third cuttings respectively in 2003. Since bluegrass was
mainly a problem in the first cutting, forage quality analysis was conducted
on the botanical components for those cuttings only. In 2002, first
cutting forage yield from the alfalfa check was 2.51 tons dry matter/acre
(T DM/A) with 46% of that yield from bluegrass. In 2003, first cutting
forage yield from the alfalfa check was 1.68 T DM/A with 30% of that
yield from bluegrass. The use of Select herbicide provided 100% bluegrass
control both years but reduced forage yield to 1.39 and 1.11 T DM/A
in 2002 and 2003 respectively. Forage yields for the alfalfa/timothy
and alfalfa/orchardgrass treatments ranged from 2.36 to 2.97 T DM/A
and were similar to the alfalfa check in 2002. In 2003, the alfalfa/timothy
yields averaged 1.71 T DM/A and were similar to the alfalfa check. The
alfalfa/orchardgrass mixtures yielded more than the alfalfa check and
averaged 2.08 T DM/A. Each of these alfalfa/grass mixtures effectively
suppressed the bluegrass. There was no bluegrass in either of the alfalfa/orchardgrass
treatments in either year and bluegrass made up no more than 8% of the
first cutting yield for either of the alfalfa/timothy treatments either
year. Forage from the alfalfa check, which had 40 and 55% alfalfa in
2002 and 2003 respectively had a crude protein (CP) value of 16.6% in
2002 and 17.4% in 2003 due to the bluegrass in this treatment, while
the alfalfa/Select herbicide treatment, had 77% alfalfa and 22.1% CP
in 2002 and had 82% alfalfa and 19.3% CP in 2003. The alfalfa/timothy
treatments averaged 14.8% CP in 2002 and 16.9% CP in 2003. Alfalfa/orchardgrass
treatments averaged 12.8% CP in 2002 and 11.1% CP in 2003. Milk yield
in 1b/T DM and in lb/A were calculated using the yield and forage quality
data. Although the milk yield/T DM was among the highest for the alfalfa/Select
herbicide treatment both years, this treatment would have produced less
milk/acre than the alfalfa/timothy mixtures in either year. These alfalfa/timothy
treatments were favored by higher yields and moderate CP values. In
2002, the alfalfa check and the alfalfa/orchardgrass treatments would
have produced milk yields/acre between the low for the alfalfa Select
herbicide treatment and the high yield for the alfalfa/timothy treatments
but not statistically different from either. Results from 2003 showed
all of the alfalfa/timothy and alfalfa/orchardgrass mixtures, as well
as the alfalfa check, would have produced more milk/acre than the alfalfa/Select
treatment. The results demonstrate the value of perennial forage grasses,
either timothy or orchardgrass, for suppression of roughstalk bluegrass
compared with chemical control of this weedy grass. They also suggest
that the ÒrecommendedÓ seeding rate of 5 lb/A of timothy or orchardgrass
in alfalfa/grass seedings is adequate for suppression of the bluegrass
and suggest that even lower seeding rates might be adequate. A new experiment
using 2.5 and 5 lb/A of timothy or orchardgrass was established in August
2003.
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