Five widely-grown picker cotton varieties were utilized in determine the effects of PGR-IV, mepiquat chloride and K(12) in multiproduct yield enhancement programs. Three low rate multiple application programs focused on PGR-IV used alone as an infurrow, pinhead square and early bloom treatment. Four additional treatment programs employed mepiquat chloride with and without polyhydroxylcarboxylicacid salts (PHCA). Of two locations tested, only the Asgrow site produced statistically significant increases in lint yields. Two of the varieties evaluated produced significant yield increases with PGR-IV used in-furrow or at 1TL, but not when this treatment was excluded. Yield increases up to 13.8 percent (115.6 lbs/ac) were observed with DPL 50 and STV 453 while smaller or no increases were observed with CB1135, HQ95 and DPL 5415. All programs using mepiquat chloride were positive with DPL 50 and STV 453, with three of four programs (DPL 50) being significant. Yield enhancement of up to 21.9 percent (183.3 lb/ac) were observed. Yield increased were primarily attributed to greater boll size and not additional bolls. PGR-IV treated plants were not observed to be shorter than the untreated check. Preliminary data with short season cotton suggests that larger, earlier treatments of PGR-IV may be required to enhance lint yields. Conditions in South Texas in 1993 ranked DPL 50> STV 453> CB 1135> HQ 95> DPL 5415 in responding to the products tested.