Gibberella Stalk Rot

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Symptoms of Gibberella Stalk Rot

Rotting at roots, crown and lower internodes are symptoms of Gibberella stalk rot
Perithecia (small black fungal fruiting structures), may develop on the stalk surface near the node (can be scraped off with fingernail)
Pink to reddish coloration of pith and vascular strands (bundles)
Pith of the inner stalk may deteriorate leaving only the vascular bundles intact
Destruction of the nodal plate
Later stages - plant turns gray-green, internodes turn straw colored or dark brown and are easily pinched between fingers
Late-season snapping of stalks at the node

Gibberella vs. Fusarium

Fusarium stalk rot

Gibberella may look similar to Fusarium stalk rot
Closely related fungi cause these diseases
Distinguish by inner stalk color
- Gibberella - red/pink
- Fusarium - white/pink/salmon

Facts

Caused by the fungus Gibberella zeae
Occurs wherever corn is grown throughout the world
Infects other cereals like wheat, barley, oats and rye
Overwinters in infected crop residue of corn or other cereals
Ascospores produced in perithecia are disseminated to corn plants by wind and rain splash
Insect injury often allows pathogen to enter the plant
Can infect corn at the leaf sheaths, brace roots or roots. Infection continues from roots into lower stem
Secondary cycles of disease are by conidia produced within disease lesions
Infection often occurs after pollination. Disease can progress rapidly with warm, wet weather during corn reproductive stages
Environmental and physiological stresses may weaken the plant and allow disease development

Impact on Crop

Greatest damage to corn crop is usually caused by stalk breakage or lodging
- Lodging slows harvest and usually results in some ears left in field
- If ears contact ground, grain quality may be reduced
Stalk deterioration disrupts water and nutrient flow, and plants may die prematurely
- Affected plants have lightweight ears and poorly filled kernels (low test weight)
Gibberella zeae may also infect ears

Management of Gibberella Stalk Rot

Select hybrids with good stalk strength and resistance to leaf diseases
Rotate crops. Corn following soybeans often has less stalk rot and higher yield than continuous corn
Use a tillage system that chops and incorporates residue to break it down
Do not use plant populations higher than recommended for the hybrid
Soil test and follow fertilizer recommendations; maintain proper nitrogen:potassium balance
Reduce stresses when possible - stalk rots are favored by plant stress following pollination
Control leaf diseases with fungicides if necessary
Control corn rootworm and corn borer.
Scout preharvest to determine stalk condition and schedule harvest based on stalk quality as well as grain moisture

Symptoms of Gibberella Stalk Rot