Arthropod Management Tests 2014, Vol. 39
doi: 10.4182/amt.2014.G10
(G10)
TURFGRASS: Tall fescue, Schedonorus arundinaceus (Schreb.); Kentucky blue grass, Poa pratensis L., and perennial rye
grass, Lolium perenne L.
EVALUATION OF INSECTICIDE APPLICATION TIMINGS AGAINST WHITE GRUBS IN COOL SEASON
TURFGRASS IN VIRGINIA, 2013
Sudan Gyawaly
Department of Entomology
Virginia Tech
Blacksburg, VA 24061-0319
Phone: (681) 285-5905
Email: [email protected]
R. R. Youngman
C. A. Laub
T. P. Kuhar
White grubs (WG): Cyclocephala lurida Bland and Popillia japonica Newman
This study was conducted to examine the efficacy of two rates of insecticides and timing of application against white grubs
in cool season turfgrass in Virginia. Treatments included low and high recommended rates of Merit (imidacloprid) and
Acelepryn (chlorantraniliprole) and an untreated check. Insecticides were applied as spring, summer, early fall and late fall
applications. Experiments were conducted at two locations: Virginia Tech Turfgrass Research Center, Blacksburg, VA, and
Tazewell County Country Club, Tazewell, VA. Turf plots 5 ft (1.5 m) by 5 ft (1.5 m) were used as experimental units.
Treatments were assigned to plots in a RCB with four replicates. Insecticides were applied as foliar sprays on 1 May
(spring), 25 Jul (summer), 11 Sep (early fall), or 3 Oct (late fall) in Blacksburg and on 24 Apr (spring), 11 Jul (summer), 10
Sep (early fall) or 1 Oct (late fall) in Tazewell using a CO2 backpack sprayer. The backpack sprayer was equipped with
4,8002VS stainless steel spray tips and calibrated to deliver 20 gpa at 40 psi. On 5 Nov in Blacksburg and 31 Oct in
Tazewell, a 1 ft² sample of turf from the center of each plot was cut and the number of live WG recorded. Treatment means
were compared using ANOVA. Means were separated using Student’s t at the 0.05 level of significance. All data were
subjected to square root transformation to normalize variance, but untransformed means are presented.
WG density was relatively low at both locations, and was comprised of predominately southern masked chafer (85% of the
total WG) at Blacksburg and Japanese beetle (70 % of the total WG) at Tazewell. There was a significant effect of
treatment at both locations. In general, all the insecticide treatments applied as spring or summer applications resulted in
relatively fewer numbers of grubs compared to early fall or fall applications of the same insecticide treatments. However,
none of the treatments had significantly lower numbers than control treated plots at both locations. No phytotoxicity was
observed from any of the insecticide treatments. This experiment was supported by products and research funding from
Dupont.
1
Arthropod Management Tests 2014, Vol. 39
doi: 10.4182/amt.2014.G10
Table 1. Blacksburg
Treatment
formulation
Rate
Application Density of WG/ft²
(oz) /acre
timing
on 5 Nov
Acelepryn 1.67SC
16.0
Acelepryn 1.67SC
8.0
Merit 75WP
8.6
Merit 75WP
4.3
Untreated check
---
1 May
25 Jul
11 Sep
3 Oct
1 May
25 Jul
11 Sep
3 Oct
1 May
25 Jul
11 Sep
3 Oct
1 May
25 Jul
11 Sep
3 Oct
1 May
1.75abc
0.00c
0.50c
0.00c
0.00c
0.00c
1.25abc
2.75ab
0.00c
0.00c
1.25abc
3.25a
1.75abc
0.00c
2.00abc
1.25abc
1.12bc
Means within each column followed by the same lowercase
letter are not significantly different according to
Student’s t (P>0.05).
Table 2. Tazewel
Treatment
formulation
Rate
(oz) /acre
Acelepryn 1.67SC
16.0
Acelepryn 1.67SC
8.0
Merit 75WP
8.6
Merit 75WP
4.3
Untreated check
---
Application Density of WG/ft²
timing
on 31 Oct
24 Apr
11 Jul
10 Sep
1 Oct
1 May
25 Jul
11 Sep
3 Oct
1 May
25 Jul
11 Sep
3 Oct
1 May
25 Jul
11 Sep
3 Oct
24 Apr
0.00d
0.00d
4.50abc
4.00abcd
0.50cd
0.25cd
1.00cd
4.00abcd
0.75cd
0.75cd
5.75ab
8.25a
1.50bcd
0.75cd
1.00cd
5.75ab
4.00abcd
Means within each column followed by the same lowercase
letter are not significantly different according to
Student’s t (P>0.05).
2