To increase phenylpropanoid constituents and energy content in the C₄ grass Sorghum bicolor (L.) Moench, sorghum genes encoding for the following proteins related to monolignol biosynthesis were overexpressed: SbMyb60 (transcriptional activator), SbPAL (phenylalanine ammonia lyase), SbCCoAOMT (caffeoyl coenzyme A 3-O-methyl transferase), Bmr2 (4-coumarate:CoA ligase) and SbC3H (coumaroyl shikimate 3-hydroxylase). Overexpression lines were evaluated for responses to yield-reducing stalk pathogens under greenhouse and field conditions. Greenhouse-grown plants were inoculated with Fusarium thapsinum (Fusarium stalk rot) and Macrophomina phaseolina (charcoal rot). No significant differences in mean lesion lengths between wild-type and F. thapsinum-inoculated overexpression lines were observed, except for smaller lesions on two of three SbMyb60 and one of two SbCCoAOMT lines. No significant differences in lesion sizes were observed in M. phaseolina-inoculated overexpression lines as compared with wild-type except one (of two) SbPAL line with larger lesions. Field-grown SbMyb60 overexpression lines inoculated with F. thapsinum had mean lesions similar to wild-type but of two SbCCoAOMT lines, one had larger lesions compared to wild-type. These data suggest that lines with increased phenylpropanoid and energy content can be effectively deployed in the field without significant yield losses occurring from stalk pathogens.