Fusarium avenaceum Isolates from Pea Are More Aggressive than Those from Wheat: Potential Implications for Pea-Wheat Rotations.

Fusarium avenaceum is an important root rot pathogen of pulses and a causative agent of Fusarium head blight of cereals. Studies have shown higher abundance of F. avenaceum in the field as a result of pulse-cereal rotations. It is not known whether this rotation can have an influence on the aggressiveness or pathogenicity of the F. avenaceum isolates, as they interact among different host species. In the present work, F. avenaceum isolates collected from common rotation crops, pea, wheat, and lentil, were assessed for root rot in pea and lentil and for head blight in durum wheat. Based on the least squares mean of root rot severity in pea and lentil, the isolate aggressiveness was categorized into low, moderate, and high. The majority of the isolates collected from pea, wheat, and lentil, respectively, were highly aggressive, moderately to highly aggressive, and less aggressive on pea and lentil. In point-inoculated durum wheat, there was no significant difference in aggressiveness between pea- and wheat-derived isolates; a direct comparison with lentil-derived isolates could not be made, as they were screened separately. When comparing the overall isolate aggressiveness, isolates recovered from pea were more aggressive on all three hosts. These data suggest that inclusion of pea in a cereal-based rotation may lead to increased incidence and severity of F. avenaceum-associated head blight in the subsequent wheat crop in the rotation.