EFFICACY OF INSECTICIDE DRENCHES AGAINST CATERPILLAR
PESTS OF COLE CROPS
Alton N. Sparks, Jr., Extension Entomologist
University of Georgia, Tifton Campus
P.O. Box 748
Tifton, GA 31794
asparks@uga.edu
Introduction
The caterpillar complex is the key arthropod pest of cole crops in Georgia. This complex
consists primarily of diamondback moth, cabbage looper and imported cabbageworm. While
these pests have historically been managed with foliar insecticides, a newly registered insecticide
chlorantraniliprole, has shown good efficacy as a soil applied systemic insecticide. This active
ingredient is available as a single product (Coragen) or as a pre-mix (Durivo; mixed with
thiomethoxam). Another active ingredient (HGW86) being developed within this chemistry has
shown similar promise. This test was conducted to evaluate the efficacy and residual control of
caterpillar pests with these products applied as a transplant drench.
Materials and Methods
Collards were transplanted into single rows on six foot beds at the University of Georgia’s
Horticulture Farm in Tifton, Georgia. Plots were established in a randomized complete block
design with four replications. Each plot was a single row with 12 plants. Plants were transplanted
with a 1.5 foot in-row spacing to aid in pest monitoring; however, insecticide rates per plant were
calculated based on the more common 12 inch in-row spacing. Treatments evaluated were:
Coragen 1.67SC at 0.066, 0.088 and 0.1 lb AI/ac, HGW 86 (200g AI/l) at 0.066, 0.134 and 0.176
lb AI/ac, Platinum 2SC at 11 oz/ac, Durivo at 10.3 and 13 oz/ac, and two experimental products.
Platinum was not expected to show activity against caterpillar pests, but was included because its
active ingredient is contained in Durivo (combined with the active ingredient in Coragen). A nontreated control was included for comparison.
Insecticide rates were calculated on a per plant basis, with an assumed row spacing of 36
inches and an in-row spacing of 12 inches (14,520 plants per acre). The calculated dose was
delivered in a 2 oz transplant water drench. Holes were punched for the transplants. A bare-root
transplant was placed into the dry hole (container grown transplants were not available for this
test) and the 2 ounce drench was applied on the roots and into the transplant hole. The hole was
then closed. Plants were transplanted and treated on 30 April, 2008.
Insects were monitored through visual plant searches. Five randomly selected plants in
each plot were visually examined and all caterpillars were identified and counted. Plot damage
ratings were determined by visually examining all plants in each plot. Damage was rated on a 0
to 6 scale: 0 = no damage, 1 = light damage (feeding) on less than ½ of plants in the plot, 2 = light
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damage on > ½ of plants, 3 = moderate damage on < ½ of plants, 4 = moderate damage on > ½ of
plants, 5 = heavy damage on < ½ of plants, and 6 = heavy damage on > ½ of plants.
All data were analyzed with the PROC ANOVA procedure of PC-SAS. Where significant
differences were detected (P<0.05), means were separated with LSD (P = 0.05).
Results and Discussion
Experimental product 1 showed no systemic activity against caterpillars in this test.
Platinum showed only minor activity against caterpillars and no effect on damage ratings, as was
expected (platinum was included as a comparison with Durivo, which contains platinum as one of
its active ingredients).
All of the remaining insecticide treatments showed excellent systemic activity against
caterpillar pests, with almost no caterpillars detected in any of these treatments through 23 days
after transplanting and only minor infestations in a few treatments at 27 days after transplanting.
Further, damage ratings were below 2 for all but one of these treatments through 33 days after
transplanting.
HGW 86 and Experimental product 2, ‘played out’ at about the same time, with
significant caterpillar populations detected at 30 days after transplanting and obvious increases in
damage ratings at 36 days after transplanting. HGW 86 did appear to show a rate effect. The
Durivo and Coragen treatments provided longer residual control, with infestations less than one
larvae per plant in most treatments through 33 days after transplanting. These treatments
maintained damage ratings below or at 2 through 36 days after transplanting. The Coragen
treatments maintained damage ratings below 3 through 47 days after transplanting. All Durivo
and Coragen treatments showed significant effects on damage ratings at 61 days after treatment
(end of the test), with the two higher rates of Coragen with only moderate damage.
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Table 1. Collards - Transplant Drench Test - Hort Hill - 2008.
Total number of caterpillars per 5 plants
Treatment
9 May 14 May 20 May 23 May 27 May
30 May
2 June
5 June
9 DAT
14 DAT 20 DAT 23 DAT
27 DAT
30 DAT
33 DAT
36 DAT
9 June
13 June
18 June
40 DAT
44 DAT
49 DAT
17.25 a
26.50 a
15.50 a
Check
0.75 a
1.75 a
3.75 a
3.25 a
8.00 a
22.0 a
34.5 a
17.75 a
Platinum
0.00 b
0.50 b
0.75 b
3.25 a
4.00 b
19.75 ab
27.75 a
16.50 ab
---
---
---
Exp. 1
0.00 b
2.50 a
5.25 a
4.00 a
3.00 bc
18.00 ab
27.50 a
16.75 ab
---
---
---
Exp. 2
0.00 b
0.25 b
0.00 b
0.00 b
0.75 cd
3.50 cd
10.0 b
7.75 cd
---
---
---
HGW0.066
0.00 b
0.00 b
0.25 b
0.00 b
0.50 cd
11.25 bc
12.5 b
9.25 bc
---
---
---
HGW0.134
0.00 b
0.00 b
0.00 b
0.00 b
0.00 d
6.25 cd
7.75 b
3.75 cd
---
---
---
HGW0.176
0.00 b
0.00 b
0.00 b
0.00 b
0.00 d
1.75 cd
8.75 b
4.25 cd
---
---
---
Durivo 10oz
0.00 b
0.00 b
0.00 b
0.00 b
0.00 d
1.25 d
0.50 b
0.75 d
3.25 b
3.00 b
6.50 b
Durivo 13oz
0.00 b
0.00 b
0.00 b
0.00 b
0.25 d
0.50 d
3.75 b
1.50 cd
3.25 b
7.50 b
4.75 b
Coragen0.066
0.00 b
0.00 b
0.00 b
0.00 b
0.00 d
0.50 d
0.50 b
1.25 cd
1.00 b
4.50 b
3.50 b
Coragen0.088
0.00 b
0.00 b
0.00 b
0.00 b
0.25 d
0.25 d
0.50 b
1.50 cd
3.25 b
2.00 b
4.00 b
Coragen0.100
0.00 b
0.00 b
0.00 b
0.00 b
0.25 d
0.00 d
0.75 b
1.75 cd
2.25 b
2.25 b
5.50 b
27
Table 2. Collards - Transplant Drench Test - Hort Hill - 2008.
Plot damage rating (0 to 6)
Treatment
30 May
2 June
5 June
9 June
13 June
16 June
19 June
23 June
26 June
30 June
30 DAT
33 DAT
36 DAT
40 DAT
44 DAT
47 DAT
50 DAT
54 DAT
57 DAT
61 DAT
Check
4.25 a
5.00 a
6.00 a
6.00 a
6.00 a
6.00 a
6.00 a
6.00 a
6.00 a
6.00 a
Platinum
4.00 a
4.75 a
5.50 a
6.00 a
6.00 a
6.00 a
6.00 a
6.00 a
6.00 a
6.00 a
Exp. 1
4.13 a
4.50 a
5.63 a
6.00 a
6.00 a
6.00 a
6.00 a
6.00 a
6.00 a
6.00 a
Exp. 2
1.00 bc
1.88 bc
3.63 b
4.63 b
4.88 b
5.25 b
5.88 a
6.00 a
5.75 ab
5.75 a
HGW0.066
1.25 b
2.25 b
4.38 b
5.25 b
5.63 a
5.75 a
6.00 a
6.00 a
6.00 a
6.00 a
HGW0.134
0.25 d
1.50 bcd
3.13 c
3.75 c
4.75 b
5.25 b
6.00 a
6.00 a
6.00 a
6.00 a
HGW0.176
0.50 cd
0.75 de
2.25 d
3.38 cd
4.25 b
4.50 c
5.50 a
5.50 a
5.50 b
5.63 a
Durivo 10oz
0.88 bcd
1.25 cde
1.88 d
2.63 ef
3.13 c
3.75 d
4.50 b
4.38 b
4.88 c
4.75 b
Durivo 13oz
0.50 cd
0.75 de
1.63 d
2.88 de
3.13 c
3.25 de
3.63 c
3.88 bc
4.00 de
4.63 b
Coragen0.066
0.75 bcd
0.75 de
2.00 d
2.50 efg
2.50 cd
2.88 ef
3.50 c
3.75 c
4.25 d
4.38 b
Coragen0.088
1.00 bc
0.50 e
1.88 d
1.88 g
2.25 d
2.75 ef
3.25 c
3.50 c
3.63 ef
3.63 c
Coragen0.100
0.50 cd
0.75 de
1.50 d
2.13 fg
2.00 d
2.38 f
3.13 c
3.38 c
3.50 f
3.50 c
28