(F45) SORGHUM: Sorghum bicolor (L.), ‘Pioneer 86G66’ EVALUATION OF SELECTED INSECTICIDES FOR CONTROL OF CORN EARWORM AND SORGHUM WEBWORM, 2006 J. H. Temple LSU Agricultural Center Department of Entomology 402 Life Sciences Bldg. Baton Rouge, LA 70803 Phone: (225) 578-1839 Fax: (225) 578-1643 E-mail:
[email protected] P. Price and B. R. Leonard LSU Agricultural Center Macon Ridge Research Station 212A Macon Ridge Rd. Winnsboro, LA 71295 Phone: (318) 435-2157 Fax: (318) 435-2133 Corn earworm (CEW): Helicoverpa zea (Boddie) Sorghum webworm (SWW): Nola sorghiella (Reilly) Selected insecticides were evaluated for control of corn earworm and sorghum webworm in three tests at the Macon Ridge Research Station (Franklin Parish). Grain sorghum seed were planted into a Gigger silt loam soil on 15 May in Tests 1 and 2 and on 20 May in Test 3. Plot size was four rows (centered on 40 inches) and 45 ft in length. Treatments were placed in a RCB design with 5 replications in Tests 1 and 2 and 6 replications in Test 3. Insecticides for Tests 1 and 2 were applied on 13 Jul and on 17 Jul in Test 3 with a John Deere high clearance sprayer and CO2 -charged system calibrated to deliver 6 gpa through Teejet TX-8 hollow cone nozzles (2/row) at 60 psi. Plants were in the “milk” stage of development when treatments were applied to the test areas. Treatment efficacy against CEW and SWW was determined at 3 and 7 DAT in Tests 1 and 2 and at 2 and 9 DAT in Test 3 by shaking 10 seed heads per plot into a 2 gal foam bucket and counting larvae of each species. Data were subjected to ANOVA and means separated according to DMRT. No rainfall occurred during these tests. In Test 1, Baythroid, Tracer, and Lannate significantly reduced CEW at 3 DAT compared to Novaluron, Lorsban, and the non-treated check. Tracer, Novaluron, and Lannate significantly reduced CEW at 7 DAT compared to the non-treated check. Tracer, Novaluron, Lorsban, and Lannate provided significantly better control of SWW at 3 DAT and 7 DAT when compared to Baythroid and the non-treated check. In Test 2, all insecticide treatments significantly reduced CEW and SWW compared to the non-treated check at 3 DAT. Novaluron 0.83EC (0.026, 0.039 lb/AI) treated plots had significantly fewer CEW than the non-treated check at 7 DAT. All insecticides significantly reduced SWW densities compared to the non-treated check at 7 DAT. No significant differences in insect numbers wee detected between formulations. In Test 3, Tracer significantly reduced CEW and SWW at 2 DAT and 9 DAT compared to that in the non-treated check. Novaluron significantly reduced CEW and SWW compared to that in the non-treated check only at 9 DAT. No phytotoxicity was observed with any of the insecticide treatments in these tests.
Test 1 Larvae/10 seed heads CEW Treatment/ formulation Baythroid 2EC Tracer 4SC Novaluron 0.83EC Lorsban 4EC Lannate 2.4LV Non-treated check
Rate/acre (lb AI) 0.025 0.05 0.039 0.5 0.4 ---
P > F (ANOVA)
SWW
3 DAT 7 DAT
3 DAT
7 DAT
6.0b 3.2b 9.2a 12.0a 4.8b 11.4a
16.2b 2.0d 7.2c 3.8cd 4.8cd 25.2a
7.8a 0.4b 1.0b 0.2b 0.2b 9.2a
< 0.01
2.8abc 1.6c 2.2bc 5.0ab 1.6c 5.8a 0.02
< 0.01
< 0.01
Means within columns followed by a common letter do not significantly differ (DMRT, P > 0.05). Test 2 Larvae/10 seed heads CEW Treatment/ formulation Novaluron 0.83EC Novaluron 0.83EC Novaluron 0.83F Novaluron 0.83F Lannate 2.4LV Non-treated check
Rate/acre (lb AI) 0.026 0.039 0.026 0.039 0.4 ---
P > F (ANOVA)
SWW
3 DAT 7 DAT
3 DAT
7 DAT
6.4b 4.0b 7.6b 6.0b 4.8b 22.4a
2.4b 2.6b 6.4ab 5.4ab 4.8ab 8.2a
12.6b 8.8b 18.0b 10.8b 5.2b 59.0a
5.2b 2.2b 6.0b 1.4b 1.0b 18.0a
< 0.01
0.02
< 0.01
0.02
Means within columns followed by a common letter do not significantly differ (DMRT, P > 0.05). Test 3 Larvae/10 seed heads CEW Treatment/ formulation Tracer 4SC Novaluron 0.83EC Non-treated check P > F (ANOVA)
Rate/acre (lb AI) 0.05 0.033 ---
2 DAT 9 DAT 0.8b 4.7a 5.0a
0.2b 1.7b 7.5a
< 0.01 < 0.01
SWW 2 DAT 0.8b 10.0ab 13.3a < 0.01
Means within columns followed by a common letter do not significantly differ (DMRT, P > 0.05).
9 DAT 0.3b 2.3b 7.8a < 0.01
