Cultural management of corn root rot (2005)

Report to the Oregon Processed Vegetable Commission

Alex Stone
OSU Dept of Horticulture

With assistance from: Mikio Miyazoe, Galen Weston, and Michael Hertel

Summary of results:

  1. Rotbusters Field Survey. Kokanee and Basin were the only varieties sampled in 2005. There was a significant relationship between radicle rot severity and gross yield for Kokanee but not for Basin. In previous years, we have shown that for Jubilee, approximately 3 tons of gross yield are lost in fields of very high root rot potential compared to those of very low root rot potential. We have also shown that Coho and SSJ+ lose about half that, or about 1.5 tons. In 2005, across all fields scouted, approximately 1.5 tons of gross yield in Kokanee were lost when this variety was planted into fields of very high root rot potential relative to planting into fields of very low root rot potential. Kokanee, Coho and Basin are higher yielding than either Jubilee or SSJ+, regardless of the root rot potential of the soil.
  2. Impacts of High Biomass Cover Cropping on Root Rot and Yield of Sweet Corn. In a research station replicated field trial, no late summer or winter cover crop treatments significantly suppressed root rot or increased yield of sweet corn. In a pseudo-replicated on-farm trial, all winter cover crop treatments (oats “Saia”, arugula “Nemfix” and mustard mix “Caliente”) strongly suppressed nodal root rot of sweet corn but had no significant effect on sweet corn yield. It is likely that the effects of cover crops on root rot and yield of sweet corn are the combined result of the effects of cover crop management on microbial activity (general suppression), nitrogen mineralization, plant available water, and possibly other soil factors. More work is required to better understand how to best manage high biomass cover crops to improve sweet corn productivity.