Arthropod Management Tests 2014, Vol. 39
doi: 10.4182/amt.2014.F36
(F36) GRAIN SORGHUM: Sorghum bicolor (L). Moench, ‘DKS 54-00’ EVALUATION OF SELECTED INSECTICIDES FOR CONTROL OF CORN EARWORM IN GRAIN SORGHUM, 2013 Sandy Steckel The University of Tennessee West Tennessee Research and Education Center 605 Airways Blvd Jackson, TN 38301 Phone: (731) 425-4718 Fax: (731) 425-4720 E-mail:
[email protected] Scott Stewart E-mail:
[email protected] Corn earworm: Helicoverpa zea (Boddie) Selected insecticide treatments were evaluated for control of corn earworm in grain sorghum at the Research and Education Center at Milan (Milan, TN). Grain sorghum was planted on 12 Jun. The test was arranged in a RCB design with 4 replicates. Individual plots were 12.5 x 30 ft. Treatments were applied with a high clearance sprayer calibrated to deliver 10.8 gpa at 32 psi with 80015 flat fan nozzles. Foliar application was made 16 Aug. Plots were sampled with a standard 15 inch sweep net. On each date, 20 sorghum heads from the center two rows of all plots were sampled by bending individual heads over the mouth of the sweep net and vigorously shaking them to dislodge insects. Insect control was evaluated 22 Aug, 6 days after treatment (6 DAT) and 28 Aug (12 DAT). Yield was taken 29 Oct by harvesting two center rows with a plot combine. Data were subjected to ANOVA and means were separated using a protected LSD. All foliar insecticides reduced the number of both small and large corn earworm larvae at both evaluations except small earworm at 12 DAT (Table 1). There was no significant effect of any treatment on yield which was numerically more in the treated sorghum compared with untreated. No phytotoxicity was observed with any treatment. This research was partially supported by industry gifts of pesticide and seed. Table 1. Number larvae per 20 heads 6 DAT
Treatment/ Formulation Stallion 3.03EC Mustang Max 0.8EC Belt 4SC Belt 4SC + Quilt Xcel 2.2F Untreated check
Rate amt product (oz)/acre 11.75 4.0 2.0 2.0 10.5 P>F
6 DAT
Corn Corn Earworm Earworm a b Large Small 0.8b 1.5b 0.5b 0.3b
0.3b 0.3b 0.0b 0.0b
6.5a 0.0001
4.5a 0.0005
6 DAT Corn Earworm c Total
12 DAT
12 DAT
12 DAT
Corn Corn Corn Earworm Earworm Earworm a b c Small Large Total
1.0b 1.8b 0.5b 0.3b 11.0a 0.0001
0.0a 0.3a 0.0a 0.0a
0.8b 0.8b 0.8b 0.3b
0.8b 1.0b 0.8b 0.3b
131.5a 131.3a 132.1a 134.9a
0.5a 0.1586
8.0a 0.0001
8.5a 0.0001
126.4a 0.1029
Column means followed by the same letter are not significantly different (LSD, P > 0.05). a Small = larvae < 0.25 inch. b Large = larvae > 0.25 inch. c Total = small + large larvae.
1
Yield (bu/acre)
