Description and Symptoms
Fusarium stalk rot (Fusarium verticillioides, F. proliferatum and F. subglutinans) is among the most common stalk rots in the Midwest, with Fusarium verticillioides the primary causal pathogen. Affected plants have shredded pith that may be a whitish-pink to salmon color and die prematurely. Brown streaks may be observed on the lower internodes. The fungi overwinter as mycelium in corn residue, other dead plant residue and in corn seed. This fungus is often found growing in healthy stalks and may cause rot only under certain conditions. Spores are spread by wind and splashing water; infection takes place through the roots, wounds in the stalk, or leaf scars.
• Target fields that have had significant foliar disease.
• Target hybrids with low stalk rot and/or standability scores.
• Evaluate at least 100 plants per field (20 plants in 5 locations).
• Use the "push test" or the "pinch test" to determine standability. If 10 to 15 percent of plants lodge or are rotted, schedule an early harvest.
No discoloration occurs on the outside of the stalk, but the nodes may appear white due to growth of the fungus on the outside of the stalk. A pink discoloration (Fig. 2, below) may be seen in the pith of infected plants when the stalks are split open. Sometimes Fusarium stalk rot may be confused with Gibberella stalk rot (because of the pink pith tissue) or with Diplodia stalk rot, however no black specks can be found on the outside of the stalk tissue.
Photo by Gary Munkvold