Large plant map data bases have been developed in the San Joaquin Valley of California (113 tests from 1982 through 1992) and in Australia (70 tests for the 1991/1992 crop year). Under conditions of high early boll set, average retention of first positions in the zone that contains 95 percent of all first position harvestable bolls was increased when the final height to node ratio increased. Yield was shown to be primarily associated with early fruit set and with vigorous growth that facilitated sustained fruit retention over more fruiting branches.