Growth pattern of corn in relation to stalk rot was first studied by WALL & MORTIMORE (1965). Seven threeways early french hybrids have been grown at two locations (Mons, northern France ; St Martin de Hinx, southern France), with a defoliation treatment in the second one. Respective dry-matter weights of leaves + sheaths, stalk, kernels + husks + cob (= whole ear), or kernels, husks + cob, were recorded six times from mid-silking to maturity. Stalk rot resistant hybrids have more stalk dry-matter, a higher stalk/whole plant ratio, and a smaller whole ear/whole plant ratio (fig. 1, table 1). When the source is reduced by defoliation, stalk rot develops on resistant and susceptible hybrids, but a little earlier on susceptible ones (table 2). Leaf area seems larger for resistant genotypes. Susceptibility to pathogens, sink-source balance and maturity-senescence-stresses relationships explain corn root and stalk rot susceptibility (fig. 2). This concept agrees with DODD one’s (1980) of « photosynthesis stress-translocation balance » concept for predisposition to stalk rot. Increased translocations from root and stalk to grain with shading, defoliation or smaller leaf area, early senescence, ear prolificacy or higher kernels number induce or increase root and stalk rot. Senescence can be increased by stresses such as drought, chilling injury or foliar diseases. Roots arc rotting first, stalk are invaded after by probably weak and opportunistic pathogens, capable of attack on senescent and sink-source unbalanced plants. Isolated Fusarium roseum are probably not the only important fungi, and roots may be invaded by different soil fungi, as it was shown by ROUHANI et al., (1979). Corn breeding for stalk rot resistance must deal with 1) active resistance in turgescent tissue, and resistance in senescent or semi-senescent tissue by phenolic compound or root mechanical resistance, 2) non senescent or late senescent plants, 3) stresses increasing senescence resistance, 4) sink-source relationships with a good ear/whole plant ratio, and last, efficient photosynthesis without foliar area restriction. Scores should be obtained only on heterotic hybrids and stalk rot scores must be rot ones and not stalk breakage ones.