the Fate of Field Paspalum Control - The Paginator

to 9.4) on May 13 (Table 1). Echelon
0.3G + Fertilizer (about 0.65 lb.
N/1,000 ft 2 ) improved color and
quality compared to all other treatments,
except CGM or Oceangro.
Our research results
Due to unusually high temperatures in
late March and early April, crabgrass
seedlings were observed on April 7,
2010, which was about 8 to 12 days
earlier than the usual emergence time.
Most germination, however, occurred
in June, but some new germination
continued to be stimulated by thunderstorms
in July and August. Since the
site was not allowed to enter a state
of drought dormancy, crabgrass populations
were kept in abeyance by the
presence of a fairly dense and competitive
turf.
Smooth crabgrass cover was
assessed on July 12 and August 13.
In general, crabgrass populations as
low as 0.5% (i.e., one half of one
percent of the plot area) in early July
invariably indicate that the level of
crabgrass control will be unacceptable
by early August (i.e., ≥120 days since
the treatment was initially applied).
Only data collected on August 13 will
be discussed, but you can make your
own judgment of each herbicide’s loss
of residual effectiveness (i.e., through
dissipation) based on the July 12
evaluation. Crabgrass cover (i.e.,
tillering) increases exponentially in late
summer in College Park, MD, and
mid-August ratings are more likely to
identify significant treatment differences.
By early September, however,
even a single multi-tillered plant can
cover 5% of the plot area, which is
above the threshold.
Crabgrass pressure was considered
to be severe compared to most commercial
lawn or golf course rough
situations. All treatments, including
Oceangro, reduced crabgrass levels
significantly compared to the untreated
control (Table 1). However, the
Table 1. Pre- and postemergence smooth crabgrass control with commercial herbicides, College Park, MD, 2010.
Quality
Color
% Crabgrass Cover
Herbicide*
Rate (lb. ai/A)
Timing
May 13
May 13
July 12
Aug. 13
Dimension 2 EW
0.38
Pre
6.8 c***
6.6 e
0.3 c
4.8 d
Dimension 0.21G
0.38
Pre
6.9 c
7.3 d
0.5 c
5.3 d
Echelon 4SC
0.75
Pre
6.9 c
7.4 d
0.0 c
5.5 d
Echelon 0.3G + Fert
0.75
Pre
8.1 b
8.4 c
0.0 c
1.3 d
Barricade 4F
0.75
Pre
6.9 c
7.1 de
0.0 c
0.3 d
Pendulum Aquacap 3.8ME
1.5 + 1.5
Pre
6.6 c
7.1 de
0.0 c
0.6 d
Pendulum Aquacap 3.8ME
3.0
Pre
6.8 c
6.9 de
0.1 c
5.0 d
Team Pro 2G (1992 product)
3.0
Pre
6.8 c
7.1 de
0.0 c
0.9 d
Tenacity 4SC
0.187 + 0.187
Pre
6.5 c
6.9 de
4.9 bc
37.8 b
Corn Glutten
20 lbs./M
Pre
9.4 a
9.4 a
2.6 bc
24.5 bc
Corn Glutten
15 + 15 lbs./M
Pre
9.3 a
9.1 ab
7.0 b
26.5 b
Oceangro 5-5-0
2.0 lbs. N/M
Pre
9.3 a
8.8 bc
7.5 b
39.3 b
**Drive XLRB 1.5SC + MSO
0.75
Post
7.3 bc
6.9 de
0.1 c
9.8 cd
**Acclaim Extra 0.57EW
0.110
Post
7.1 c
7.4 d
0.0 c
5.0 d
**Tenacity 4SC + Activator
0.187 + 0.187
Post
7.4 bc
7.1 de
0.0 c
0.6 d
Untreated
—
—
7.1 c
7.0 de
12.8 a
63.5 a
*** Preemergence (Pre) treatments were applied April 2, and sequential treatments were applied May 18, 2010.
*** Postemergence (Post) treatments were applied June 29 (2 to 4 tiller crabgrass); the Tenacity sequential treatment was applied July 13, 2010.
*** Means in a column followed by the same letter are not significantly different according to Fisher’s LSD, P ≤ 0.05.
SUMMER 2011
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