Stalk rot is of generalized occurrence in the major maize (Zea mays) growing regions of the country. Seeking to evaluate the effects of inoculum concentration and plant age on the reaction of maize to Fusarium moniliforme, the stalks of three maize hybrids were artificially inoculated at the ages of 30, 55 and 80 days after planting using the inoculum concentrations of 1 x 10(4), 5 x10(5) and 1 x10(7) conidia /ml. Completely randomized block designs, respectively, with four and five replications were utilised in these experiments, being each plot constituted of fifty plants. The inoculations were carried out at the center of the second internode extended above soil level. Disease assessement was conducted 120 days post-planting, by using a score scale ranging from 1 to 9, based on the internal necrosis of the stalk. By harvest time, the number of fallen plants and the grain yield were evaluated. The lignin and tanin contents of the rind, and of the internal part of the inoculated internode were also analyzed for different treatments. A significant difference among hybrids in their levels of resistance to F. moniliforme was observed, regardless of the inoculum concentration used and age of inoculation. On the other hand, there were no significant differences in disease levels obtained when stem inoculations with F. moniliforme were performed at different plants ages. Tanin contents were not significantly different among the hybrids, whereas lignin content was significantly related to the level of resistance of the three hybrids evaluated.
