The early season complex of insects and spider mites that occurs on seedling cotton (Gossypium hirsutum L.) in northeast Louisiana is considered to be of economic importance. Numerous seed treatment, foliar, and infurrow systemic insecticide tests conducted at the Northeast and Macon Ridge Research Stations indicate yield and maturity losses of sufficient magnitude to justify annual treatment.In 1986 a test was conducted at the two locations to evaluate the complex. The test was conducted on loessial silt loam soils and irrigated at the Macon Ridge Station. Soil type at the Northeast Station was an alluvial silt loam and the test not irrigated. New plant washing techniques and binocular microscope counting were used instead of conventional infield whole plant sampling. Control regimes at planting were main plots and eight subsequent control options were subplots. At planting main plots control regimes consisted of: (1) Infurrow applied Terraclor Super-X (TSX) (Terraclor 1.0 lb + Terrazole 0.25 lb ai/A). (2) Orthene BOS seed treatment (O.S.T.) (Acephate 8 oz/cwt.) + TSX (3) Infurrow applied Temik 15G (TK) (Aldicarb 0.5 lb ai/A) + TSX (4) Double treated seed (U.T.C.) (Captan + Vitavax). Subplot treatments consisted of; (1) Pre-square treatments (P.S.) (2) Pre-bloom treatments (P.B.) (3) Bloom treatments (B) (4) P.S. + P.B. (5) P.S. + M.P. (6) P.B. + M.P. (7) P.S. + P.B. + M.P. (8) Untreated check (U.T.C.). Pre-square (P.S.) foliar treatments were Monitor 4 (Methamidophos 0.2 lb ai/A) applied twice at five day intervals. Criteria used for initiating the foliar treatments was the appearance of immature thrips on seedling cotton in the Temik 15G main plots. Insect pest species found on cotton in the pre-square stage were Frankliniellia fusca, (Hinds), Frankliniellia tritici, (Fitch), Sericothrips variabilis, (Beach), Microcethalothrips abdomalis. Cotton aphids (Aphis gossypii, (Glover), and spider mites (Tetranychus Sp. ) were present at low levels. Thrips populations as sampled peaked 16 and 23 May at 18 and 30 thrips/plant.

In 1986 first harvest yield increases resulting from the P.S. treatments were 8% (main plot 1), 15.8% (main plot 2), 12.5% (main plot 3) and 12.7% (main plot 4) at the Northeast Research Station. At the Macon Ridge Station, increases of 1.2% (main plot 1), -17.7% (main plot 2), 14.5% (main plot 3), and 43.6% (main plot 4).

At the Northeast Research Station the following data relative to pest effects on the cotton were collected. Leaf area as measured on 23 May was significantly different due to main plot effect and also due to P.S. treatment effect. On 29 May stand loss was significantly greater in the U.T.C. than for all other main plots. No significant effects on stand were caused by foliar treatments. On 9 April plant height in the Temik 15G main plots was significantly greater (C.V. 9.65%) than other treatments. Orthene SOS seed treatment main plot height increases were 3 inches greater than for the fungicide and control main plots, but 3 inches less than the Temik 15G treatments. Plant height measurements averaged across all mains resulted in significant increases for subplot treatments 1, 4, 5, and 7 which received P.S. treatments. By subplot effect the P.S. treatments significantly increased height in the control and fungicide main plots only. The P.S. treatment effect on flowering of subplot I was carried into the third observation date of 7 July, after which other pest effects on fruiting were apparent. These results show positive increases in first harvest yield with the applications of (Monitor 0.2) pre-square treatments. The increases were additive to those obtained from main plot effects, including Temik 15G and Orthene BOS. The data suggest profit potential could be increased since greater percent first harvest and improved grades could be obtained.