profile8

Disease Profile 8
Gibberella Stalk Rot

Image Courtesy of:
http://ohioline.osu.edu/ac-fact/0033.html

Last updated by
Nick Dolezal
on April 2nd, 2002

Common Names of Gibberella Stalk Rot:

-Stalk Rot

Causal Agent:

Species:
    Gibberella zeae

Class:
    Fungi

Order:
Ascomycetes

Host Range:

Here are some of the alternate crops, ornamentals, and weeds that Gibberella can survive on:

Field Crops	Ornamentals	Weeds
Corn	none found	none found
Sweet Corn
Wheat

Geographical Range:

Gibberella stalk rot can be found throughout the world wherever corn is grown.

Symptoms:

Generally stalk rot is more noticeable during extreme weather conditions in combination with unbalanced soil fertility and high plant populations which all contributes to high plant stress. In extreme cases, corn fields may become totally leveled due to the deterioration of stalk strength. A stalk can be taken and cut in a cross section near the break. If this type of stalk rot is present, a pinkish color should be identifiable within the pith of the stalk as the picture at the top of this page portrays. Generally, the pink color can be identified more easily near the internodes of the stalk.

Dissemination:

The plant pathogen being examined here is generally carried to other plants by wind or water movement. Stalk rot can also be introduced into a new field by the transport of infected plant material carried on farm equipment. Ascospores are produced from inoculum present in infected plant residues during the spring. These spores infect a corn plant by entering the stalk through a wound. Ascospores may get to a corn stalk by means of water splash or by wind. Stalk Rot may be more prevalent during periods of dry weather early in the growing season followed by wet weather near the corn silking stage.

Disease Cycle:

Gibberella generally enters the base of the plant and becomes evident after silking. Corn plants tend to be more resistant to infection from this fungus prior to this time. Ascospores are produced in perithecia and on mycelium during periods of moist weather giving way to primary inoculum for plant infection. As the season progresses, conidia may be produced in infected corn plants allowing for secondary inoculum to infect more plants.

Control Measures:

Stalk rot is most easily controlled by the use of resistant varieties. Also, providing the corn plants with proper nutrition and reduced population allows for reduced onset of stalk rot. Anything that reduces plant stress will reduce the effects of stalk rot. As a result, weeds and insects should be monitored and controlled appropriately. As Gibberella can infect wheat, a farmer should rotate to a non host crop such as soybeans to reduce inoculum present in the field for infection. Tillage may provide some assistance in controlling the pathogen by burying inoculum. Since the pathogen enters a wound present on a plant, farmers should limit field cultivation and traffic while the plant is actively growing in the field. Finally, if the disease has been identified in the field, farmers may be able to reduce the effects and resulting yield loss by harvesting early.

Recent Research-Summary: