Abstract: Information is limited about dry down of corn stover fractions of standing plants in the field after grain physiological maturity has been reached, especially for the new Bt hybrids. These data are important in scheduling grain/stover harvest for bioenergy production or other industrial applications. Dry down of the aboveground morphological components of two corn cultivars (Pioneer 32K61 and 32K64 Bt) was studied in standing plants from roughly one week before the R6 stage (40% MC w.b.) until four weeks after grain was harvested from surrounding field plots. When moisture of the various aboveground corn plant fractions was expressed on a dry matter basis and plotted over time, the resulting curves visually displayed a linear decrease to a flat asymptote. Linear multi-source regression indicated that dry down of all plant fractions of Bt and non-Bt hybrids is a linear process and that rates of dry down did not differ between cultivars except for the husk.