Goss' bacterial wilt and blight (leaf freckles and wilt)
September 09, 2009
This disease is caused by the bacterium Clavibacter michiganense subsp. nebraskensis (Vidaver & Mandel) Davis et al. Several strains of the pathogen are known to exist. Goss' wilt is a true Nebraska native. It was first discovered on corn in two south central Nebraska counties in 1969. Since then it has been identified across the entire U.S. Corn Belt. Hosts of the bacterium include corn, green foxtail, barnyard grass and shattercane. Artificial inoculation has also been successful on grain sorghum, eastern gamagrass, Sudangrass, sugarcane and teosente.
C. michiganense subsp. nebraskensis over seasons on crop debris and in and on corn kernels. The bacterium can also survive in irrigation water during the growing season. Infection occurs directly through host tissue or through wounds caused by sandblasting, hail, heavy rain or wind. Leaves, 01 stems and roots serve as infection sites. Plants may become infected at any stage of development.
Symptoms
A variety of symptoms are produced on corn. Streaks of water soaked tissue develops parallel to the veins. They are yellow to grayish green and wavy with irregular margins. Stripes may be reddish on some hybrid and may be confused with symptoms of Stewart's wilt. These lesions are caused by a toxin produced by the bacterium. The most characteristic of the disease is leaf freckling which commonly develop in streak lesions. Small dark green to black water soaked spots (freckles) develop along the veins. The spots appear greasy. A sticky exudate also forms in the streak. The exudate eventually dries leaving a glistening residue on the leaves. Leaf lesions also enlarge and coalesce, blighting large areas of tissue.
A vascular wilt is also associated with Goss' wilt. Plants systemically infected typically have a dry or water soaked brown rot in the lower stalk and roots. The vascular system is discolored and an orange bacterial exudate is present in vessels. Systemically infected plants wilt and die. They commonly stunted. The plants may exhibit the leaf blight symptoms or they may simply show symptoms of drought stress.
Plant Health Management
Resistant Hybrids
Resistant material is available for field corn and sweet corn but little is available for popcorn.
Residue Management
Destruction of crop residue will lower the amount of inoculum available. However, this practice is not practical in a conservation tillage operation. Rotation to a non host crop such as soybeans, dry beans or alfalfa also reduces the amount of corn residue and is a more viable option in most situations.
References
McGee, D.C.1994. Maize Diseases, A reference source for seed technologists. American Phytopathological Society, St. Paul MN. pp 35-36.
Schuster,M.L.1975. Leaf Freckles and Wilt of Corn Incited by Corynebacterium Nebraskense Schuster, Hoff, Madel, Lazar, 1972. Univ. of Nebraska Agricultural Experiment Station, Institute of Agriculture and Natural Resources. Research Bulletin 270.
Schurtleff, M.C. 1980. Compendium of Corn Diseases (2nd. ed.) American Phytopathological Society. St. Paul, MN pp 7-8.
Smidt,M.L. and Vidaver, A.K. 1987. Variation among stains of Clavibacter michiganense subsp. nebraskensis isolated from a single popcorn field. Phytopathology 77: 388-392.
Wysong, D.S. and Doupnik, B.Jr. 1977. Goss' Bacterial Wilt and Blight of Corn. Univ. of Nebraska Cooperative Extension Serv. and Institute of Agriculture and Natural Resources NebGuide G 74-147.
Source:
This page was drafted by: Jane Christensen, Department of Plant Pathology, University of Nebraska-Lincoln
Disease images were provided by: Dr. David Wysong, Department of Plant Pathology, University of Nebraska-Lincoln
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