(F27) COTTON: Gossypium hirsutum L., 'STV 5599BGRR' EVALUATION OF SEED/SOIL TREATMENTS AND FOLIAR INSECTICIDE COMBINATIONS AGAINST THRIPS ON COTTON SEEDLINGS, 2005 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] K. D. Emfinger P. P. Price B. R. Leonard Tobacco thrips: Frankliniella fusca (Hinds) Flower thrips: Frankliniella tritici (Fitch) Selected seed or soil treatment and foliar insecticide combinations were evaluated for control of thrips at the Macon Ridge Research Station (Franklin Parish). Plot size was four rows centered on 40-inches and 50 ft in length. Treatments were placed in a RCB design with four replications. Insecticide-treated seed, untreated seed, and untreated seed with Temik 15G applied in-furrow were planted into a Gigger silt loam soil on 4 May. Foliar insecticides were applied on 31 May with a John Deere 5400N tractor and compressed air system calibrated to deliver 10 gpa through Teejet 80015 flat fan nozzles (two per row) at 30 psi. Insecticide efficacy was measured by randomly selecting 10 plants per plot and counting the number of thrips immatures at 20 DAP (24 May) and at 2 (2 Jun) and 7 DAT (7 Jun) after the foliar spray. Plant samples were processed using whole plant washing procedures to remove thrips. Thrips were counted using a dissecting microscope. Ten plants in each plot were visually rated for thrips injured leaves at 2 DAT (2 Jun) using a 0 (no leaf injury) to 5 (severe leaf damage) scale. Plots were harvested with a mechanical cotton harvester and seedcotton yield was taken from the center two rows of each plot. Data were subjected to ANOVA and means separated according to DMRT (P = 0.05). Total rainfall of 4.95 inches was recorded between planting and the final efficacy rating. At 20 DAP and 2 DAT (2 Jun) with Orthene, immature thrips were significantly lower in the Gaucho, Cruiser, and Temik treated plots compared to plots planted with untreated seed. Plots with insecticide-treated seed and Temik had significantly fewer thrips at 7 DAT (7 Jun) compared to that in plots planted with no seed treatment, or no seed treatment followed by (FB) Orthene, and the untreated. The Orthene spray did not reduce immature thrips below that in the seed treatment alone plots at 2 or 7 DAT. Plots planted with Gaucho or Cruiser treated seed followed by the Orthene spray and those treated with Temik significantly yielded more seed cotton than the plots planted with no seed treatment. All plots treated with Gaucho, Cruiser or Temik had a lower visual rating and healthier plants compared to plants in plots planted with no seed treatment. No phytotoxicity was observed. Thrips/10 plants (DAP) Treatment/ formulation Temik 15G Cruiser 5FS Cruiser 5FS Orthene 97S Gaucho 600F Gaucho 600F Orthene 97S Orthene 97S Untreated check P > F (ANOVA)
Rate amt (AI)/unit 0.75 lb/acre 0.25 mg/seed 0.25 mg/seed 0.2 lb/acre 0.6 mg/seed 0.6 mg/seed 0.2 lb/acre 0.2 lb/acre --
Application typea IF S S F S S F F --
(7)
Visual ratingb
Seed cotton yield lb/acre
(20)
(2)
1.0b 1.3b
6.5b 6.8b
5.9c 18.3bc
1.5b 1.4b
1513.5ab 1365.3bc
0.8b 0.5b
2.5b 8.5b
6.0c 10.0bc
1.4b 1.3b
1639.5a 1457.3abc
1.0b 17.3a 22.0a
1.8b 6.0b 63.3a
6.3c 30.3b 50.8a
1.8b 3.3a 3.3a
1591.2ab 1398.9bc 1319.9c
< 0.01
0.01
< 0.01
< 0.01
0.04
Means within columns followed by a common letter are not significantly different (DMRT, P > 0.05). a IF = in furrow application, S = treated seed, F = foliar application on 31 May. b Rating scale of 0 (no leaf injury) to 5 (severe leaf injury).
