Submitted to: Canadian Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2003
Publication Date: N/A
Interpretive Summary: Serious crop losses are frequently caused by a root rot (Aphanomyces euteiches) in the production of pea. There is no disease resistance nor successful fumigant. Poor soil drainage is nearly always associated with the damage. This research indicated that crop residue from oat reduces the root rot disease when soil compaction is controlled. One of several mechanisms was evaluated in this report. Should this mechanism be operative in the field the control focus would involve oat varieties that would induce inoculum germination when the host pea plant had not yet been planted. Thus there will be a reorientation of cultural control, when disease resistance is yet weak. This information can be used by Extension; customers, and stakeholders to improve pea production.
Technical Abstract: Root rot (Aphanomyces euteiches Drechs.) is a serious econimic threat to pea (Pisum sativum L.) production in the North Central and Pacific Northwest U.S. regions. The disease is responsible for an estimated 10% annual crop loss. A late summer seeded oat (Avena sativa L.) crop prior to spring pea planting reduced disease severity. To better understand the beneficial effect of oat on A. euteiches, zoospores, mycelia, and oospores were treated in culture with oat extract diluted with sterile, deionized water to 0 (control), 30, 50, 70, and 90% oat extract. Two oat varieties, 'Bay' and 'Ogle', were used in the study. Oat extract significantly enhanced pathogen spore germination and mycelial growth. Generally 90% concentrations of oat extract produced greater mycelial weights than 30% concentrations in zoospore experiments. In contrast, experiments with mycelia showed 30% oat extract concentrations generally produced greated mycelial weights than 90% oat extract concentration. Oat extract concentration had no effect on mycelial weight in experiments with oospores. The oat variety 'Ogle' generally produced greater mycelial weights than 'Bay' in zoospore and mycelia experiments, but oat variety was not tested in oospore experiments. There was no pathogen growth in the water control. These results demonstrated that oat extract promoted germination and growth of A. euteiches in culture.