DISTRIBUTION OF FUMONISINS IN MAIZE EARS INFECTED WITH STRAINS OF FUSARIUM-MONILIFORME THAT DIFFER IN FUMONISIN PRODUCTION

Strains of Fusarium moniliforme (Gibberella fujikuroi mating populatio n A) that differ in fumonisin production in vitro were previously iden tified in a Kansas field population. One strain that produced high lev els of fumonisins and two strains that produced very low levels of fum onisins were applied to maize kernels at planting at the Rocky Ford Fa rm near Manhattan, Kansas. The distribution of fumonisins in symptomat ic and symptomless kernels from individual harvested ears was determin ed by high performance liquid chromatography, and the distribution of the three applied strains in the kernels was determined by vegetative compatibility group analysis. Both symptomatic and symptomless kernels were extensively colonized with F. moniliforme, but the highest level s of fumonisins were in the symptomatic kernels. All three applied str ains were recovered from kernels in 1993, and two of them were recover ed from kernels in 1994. However, a high frequency of ear and kernel i nfection with a strain that produced little fumonisin in vitro did not consistently decrease the level of fumonisins. The frequency of infec tion with fumonisin low-producing strains may have been too low for co mpetitive exclusion of naturally occurring fumonisin high-producing st rains. Also, strains that are low-fumonisin producers under laboratory conditions may be high producers in the field.