1. A system for measuring plant attributes during harvesting of a row crop comprising: a harvester having a row unit with stripper plates forming a gap therebetween to receive an individual plant in a row; a plant attribute sensor coupled to the row unit; a digital a priori plant location map identifying an anticipated presence of the individual plant in the row of plants; and an electronic control unit (ECU) coupled to the plant attribute sensor and configured to retrieve and use the a priori plant location map to anticipate presence of the individual plant to be harvested and to use the anticipated presence of the individual plant as part of determining a yield of the individual plant based upon signals the plant attribute sensor.