Tarnished plant bug, Lygus lineolaris, nymphs were placed on cotton terminals at different dates in 1985 to determine the effects of inflation time on harvest dates and total yield Cotton planted May 7 had nymphs applied on June 24 (A), July 8 (B) and July 29 (C) at the rate of 9 nymphs/meter of row. The eight treatments consisted of one treatment with no infestation (check), three with a single infestation, three with two infestations, and one with all three infestations. Treatments were applied to five cultivars, 'Coker 201', 'Stoneville 825', 'DES 422', 'Deltapine 61' and 'Stoneville 506' in eight replications. Harvest dates were Aug. 29, Sept. 10, Sept. 26 and Oct. 16. The experimental design was a split-plot with infestation dates used as whole plots.

The percent of total lint harvested was 12, 46, 35, and 7 for the first, second, third and fourth harvest date, respectively. Lint harvested on the second date was 546, 509, 497, and 510 kg/ha for the check (no infestation) A, B, and C dates of infestation, respectively. The average total yield for the check A, B, and C dates of infestation was 1153, 1103, 1121, and 1107 kg/ha, respectively. Significant yield effects (P = 0.05) were shown with A X C and B X C for second harvest date and total lint. A significant variety X C interaction (P = 0.05) was shown for the third harvest and total yield. This study indicates that the third infestation date when in combination with an earlier infestation can significantly reduce yield. Also, varieties are detrimentally affected by the C infestation date, which was during blooming. Since tarnished plant bugs are generally thought of as early season pests, these data indicate that they affect yields further into the fruiting stage than generally thought.