Proceedings of the Sixty-first Annual Meeting of the Northeastern ...

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PRELIMINARY STUDY AT FOUR LOCATIONS ON USING GROWING DEGREE-DAYS
TO APPLY A PREMERGENCE HERBICIDE. M.A. Fidanza, The Pennsylvania State
Univ., Reading, J.A. Borger and M.B. Naedel, The Pennsylvania State Univ., University
Park, C.A. Bigelow, Purdue Univ., West Lafayette, IN, and P.C. Bhowmik, Univ. of
Massachusetts, Amherst.
ABSTRACT
Crabgrass (Digitaria spp.) is a troublesome and problematic annual grass weed
in cultured turfgrass. Preemergence herbicides are often used for the control of
crabgrass in lawns, however, in some years the level of control is considered marginal
or not commercially acceptable. The issue of poor or unacceptable crabgrass control
from preemergence herbicides in lawns may involve the early-to-mid spring application
timing of these kinds of products. Therefore, the objective of this research was to
attempt to determine optimum application timing for a commonly used preemergence
herbicide for the control of crabgrass in cool-season turfgrass maintained as a lawn.
The same field study was conducted during March through September, 2006, on a
mixed stand of cool-season turfgrass at four locations: (1) Bellewood Golf Course,
North Coventry, PA, (2) Pennsylvania State University, University Park, PA, (3) Purdue
University, West Lafayette, IN, and (4) University of Massachusetts, Amherst, MA. The
preemergence herbicide prodiamine (trade name = Barricade 65WG) was applied at
0.55 kg ai/ha (0.75 lbs product/A) over a range of 15 different cumulative growing
degree-day accumulations, as follows: 0 - 10, 11 – 20, 21 – 30, 31 – 40, 41 – 50, 51 –
60, 61 – 70, 71 – 80, 81 – 90, 91 – 100, 101 – 120, 121 – 140, 141 – 160, 161 – 180,
and 181 – 200. A base temperature of 10 C (50 °F) was used to calculate cumulative
degree-days from soil temperatures derived from each location via satellite weather
data. An untreated check was also included in the treatments, which were arranged in
a randomized complete block design with three or four replications depending on the
study location. Also, individual plot size varied according to study location, and mowing
height ranged from 5.0 to 7.5 cm (2 to 3 inches). At each location, the treatments were
applied from flat-fan nozzles with a CO 2 -powered backpack sprayer through an average
of about 408 gal water carrier per ha (1 gal water per 1000 sq ft) at 250 kPa (35 psi).
Preliminary analysis revealed that crabgrass control varied among the application
timings at all four locations. Also, preliminary analysis of the data from all four locations
indicated a need for improved accuracy with accessing soil temperature-based
cumulative growing degree-day information.
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