Research Report
Acelepryn & HGW86 20SC White Grub Control in Turfgrass (2012 DuPont Field Trials) Virginia Tech Researchers: Rod Youngman, Ph.D., Professor; Curt Laub, Research Associate; Shaohui Wu and Sudan Gyawaly, Graduate Students, Department of Entomology Sponsors: DuPont Professional Products, Virginia Agriculture Council and Virginia Turfgrass Foundation
To
evaluate the efficacy of various soil insecticides against white grubs on golf course turf, we conducted research at two locations in southwest Virginia in 2012: (1) Tazewell Country Club, where the turf is an 80% fescue/20% bluegrass mixture, and (2) the Virginia Tech Turfgrass Research Center in Montgomery County on 100% ‘Penncross’ bentgrass.
Table 1. Treatment list for 2012 Dupont Acelepryn & HGW86 20SC white grub efficacy trials in Tazewell and Montgomery Counties, Virginia. Trt. No.
Application Timing1
Treatment/ Formulation
Application Rate (amt. product/acre)
1
Early
DPX-HGW86 20SC
4.0 fl. oz.
2
Early
DPX-HGW86 20SC
6.0 fl. oz.
3
Early
DPX-HGW86 20SC
8.0 fl. oz.
4
Early
Acelepryn 1.67SC
8.0 fl. oz.
5
Early
Merit 75WP
6.4 oz.
Meridian 25 WG +
8.58 oz.
DPX-HGW86 20SC
10.3 oz.
6
Early
7
Late
DPX-HGW86 20SC
4.0 fl. oz.
8
Late
DPX-HGW86 20SC
6.0 fl. oz.
9
Late
DPX-HGW86 20SC
8.0 fl. oz.
10
Late
Acelepryn 1.67SC
8.0 fl. oz.
11
Late
Merit 75WP
6.4 oz.
Meridian 25 WG +
8.58 oz.
DPX-HGW86 20SC
10.3 oz.
12
Late
13
--
Untreated check
1 Early Application: June 7 at Site 1 (Tazewell); June 13 at Site 2 (Montgomery). Late Application: July 11 at Site 1 (Tazewell); July 12 at Site 2 (Montgomery).
Our research
The treatments used in these trials are shown in Table 1. Plot size was 5 ft. by 5 ft. Application timings were either early (June) or late (July). Early applications were applied on June 7 at Site 1 and on June 13 at Site 2, and late applications were applied on July 12 at Site 1 and on July 11 at Site 2. Liquid insecticide treatments were applied as foliar sprays using a CO2 backpack sprayer equipped with four 8008VS stainless steel spray tips and calibrated to deliver 80 gpa at 40 psi. Approximately 1/2" of overhead irrigation water was applied immediately after treatments were applied. No fungicides were applied at either site. White grub counts were taken on September 14 at Site 1 and on September 13 at Site 2. A sod-cutting machine was used to cut a 12" wide by 1" deep strip the length of each plot: in each untreated check plot, a 2' section of turf was
Table 2. White grub counts in Tazewell County, Virginia (Site 1). Application Rate (amt. product/acre)
White grubs per sq. ft. (+ SEM)
--
9.50 (1.17) a
DPXHGW86 / June / Low
4.0 fl. oz.
9.00 (1.08) a
DPXHGW86 / June / Med.
6.0 fl. oz.
3.00 (0.41) b
Meridian+DPXHGW86 / June
8.58 + 10.3 oz.
3.00 (0.71) b
Meridian+DPXHGW86 / July
8.58 + 10.3 oz.
1.50 (1.50) bc
DPXHGW86 July / High
8.0 fl. oz.
1.25 (0.75) bc
DPXHGW86 June / High
8.0 fl. oz.
1.00 (0.71) bc
6.4 oz.
0.75 (0.48) bc
Acelepryn / June
8.0 fl. oz.
0.50 (0.50) bc
DPXHGW86 / July / Low
4.0 fl. oz.
0.50 (0.29) bc
DPXHGW86 / July / Med.
6.0 fl. oz.
0.00 (0.00) c
Acelepryn / July
8.0 fl. oz.
0.00 (0.00) c
6.4 oz.
0.00 (0.00) c
Treatment/Timing1/ Formulation Untreated check
Merit / June
Merit / July
1 Early Application: June 7. Late Application: July 11. The treatment source of variation for white grubs was highly significant (P < 0.0001) according to ANOVA. Statistical analysis including Tukey’s HSD was performed on square root transformed data (x + 0.5)1/2. Actual treatment means are shown in table. Means within a column by site followed by the same letter are not significantly different (P > 0.05; LSD).
22 | Virginia Turfgrass Journal May/June 2013 www.vaturf.org