Vegetative phase change in maize and its association with resistance to fall armyworm

Vegetative development in maize can be divided into juvenile and adult phas es. Each phase is characterized by distinctive morphology and physiology. T wo maize hybrids with resistance to fall armyworm feeding, two susceptible hybrids, and a hybrid with an intermediate level of resistance were evaluat ed for the timing of juvenile-adult phase transition and duration of transi tion period. The fall armyworn resistant hybrids completed the phase transi tion earlier than the susceptible hybrids. Earlier phase change was highly correlated with resistance to fall armyworm as indicated by reduced plant d amage and lower larval weights in the field and laboratory bioassays. When using leaves collected at different vegetative stages of plant development and lyophylized for artificial diet bioassays, fall armyworm resistance was highly correlated with juvenile-adult phase transition.