Effective late-season management with COTMAN, the COTton MANagement system developed at the University of Arkansas, requires accurate identification of the last effective boll population. A nonirrigated cotton study was conducted at the University of Arkansas Northeast Research and Extension Center at Keiser on Sharkey silty clay (Chromic Epiaquerts) to compare ultra narrow row (UNR) to conventional, 38-inch (CONV) production. White flowers were tagged throughout the bloom period and bolls were mapped at harvest. Nodes above white flower (NAWF) at first flower averaged 8.5 and 6.5 for the CONV and UNR plots, respectively, lower than the 9.25 for the COTMAN target development curve (TDC). NAWF=5 averaged 67 and 62 DAP for the CONV and UNR plots, respectively, less than the 80 DAP for the COTMAN TDC. Significantly more flowers per acre were associated with UNR for 1 ≤ NAWF ≤ 3, and with CONV for 6 ≤ NAWF ≤ 8. UNR plots yielded more than CONV, with 51% of UNR yield associated with NAWF = 3 and 4; 31% of CONV yield was associated with other than first position bolls. Findings will be compared with similar data from other locations to determine whether a different target development curve is required for UNR cotton.