RESPONSE OF COWPEA CULTIVARS TO INFECTION BY PHOMA-BAKERIANA SACC IN SOUTHWESTERN NIGERIA

Aspects of disease development, plant to seed transmission, pre-emerge nce mortality and seed to plant transmission were investigated in arti ficial inoculations of ten cowpea cultivars with Phoma bakeriana. The cultivars differed significantly in their response to infection relati ve to disease symptom severity. Incompatible reactions (resistance) we re established in cultivars TVu 4569, VITA-3, VITA-6 and TVX 1193-7D. Cultivars TVx 3048-02D and TVx 944-02E were highly susceptible while t he remaining cultivars were either slightly or moderately susceptible to infection by P. bakeriana. Plant to seed transmission was establish ed in all compatible reactions and varied from 8.6% in the slightly su sceptible VITA-5 to 29.7% in the highly susceptible TVX 944-02E. Seed- borne disease incidence was highly correlated with disease severity (r = 0.94; P = 0.01). Seeds harvested from susceptible cultivars showed 9.2 - 20.5% pre-emergence mortality. Seed to plant transmission was no t established in seedlings derived from infected seeds and grown in th e glasshouse for five weeks.