AUTHOR: Elmer*, W. H.1, Robertson, C. L.2, Useman, S.2, Schneider, R. L.2, and
O’Donnell, K.3, 1The Connecticut Agricultural Experiment Station, New Haven, CT
06511;2 Dept. of Plant Pathology and Crop Physiology, Louisiana State University
Agricultural Center, Baton Rouge, LA 70803; 3NCAUR, ARS, USDA, Peoria, IL 61604
TITLE: FUSARIUM SPECIES ASSOCIATED WITH DECLINING SPARTINA IN
AREAS AFFECTED BY SUDDEN WETLAND DIEBACK
LOCATION: Coast Guard Academy, NL, CT
ABSTRACT: Sudden wetland dieback (syn Brown marsh) is a phenomenon of unknown
etiology. Characteristics include a rapid death of brackish and salt water wetland grasses,
primarily Spartina alterniflora and S. patens. Declining plants from affected areas along
the coast of Louisiana, and in Madison, Connecticut, were sampled to determine if fungal
pathogens could be found and associated with declining plants. Foliar and root tissue
were sampled, washed in distilled water, surface disinfested in 10% household bleach,
rinsed, and placed on an agar medium. Colonies of Fusarium spp. were recovered.
Isolates were identified using spore and colony morphology and by amplifying partial
sequences of the elongation factor alpha gene using PCR. An undescribed species was
found among the Louisiana isolates and shown to belong to the African clade of the
Fusarium sexual stage, Gibberella fujikuroi. These findings suggest that the Louisiana
species were introduced to North America. The Connecticut isolates were distinctly
different from the Louisiana isolates and represented new species that belong to the
trichothecene-producing clade of Fusarium, a group of Fusarium species that produces
mycotoxins. Pathogenicity tests have shown that these Louisiana and Connecticut species
are capable of inciting lesions on the plant; however, their role in sudden wetland dieback
is unclear.