Infected areas of field appear white or bleached plants contain empty heads and appear stunted. Extensive root rot occurs. Hyphopodia are formed on runner hyphae. Resulting damage restricts nutrient and water flow.
Most infection occurs from mycelia in debris.
All Decline occurs after four years continuous cropping, suppression of the pathogen is due to buildup of soilborne Pseudomonas bacteria. Much research has been conducted to develop biological controls from this observation. Current control measures, however, are still based primarily on rotation. Inoculum source for Group II isolates is infected corn debris Infection is associated with flowering and high humidity F. culmorum is the pathogen in cooler climates such as Europe. This is especialy a problem if one is trying to compare data from papers published 30 or 40 years ago with more recent literature.