Association Between Fusarium spp. on Spartina alterniflora and Dieback Sites in Connecticut and Massachusetts

Sudden vegetation dieback (SVD) is defined as the loss and lack of recovery of smooth cordgrass (Spartina alterniflora) in salt marshes. A new species of a moderately pathogenic fungus called Fusarium palustre is consistently found in SVD sites, but greenhouse tests revealed that it is not capable of causing mortality of healthy plants. Similarly, root-knot nematodes (Meloidogyne spartinae) are also found in SVD sites, but their incidence in marshes affected by SVD is not known. To understand more about the ecology of F. palustre and M. spartinae, salt marshes along Connecticut's Long Island Sound and Massachusetts' Cape Cod that exhibited SVD and those that did not, were visited during the summers of 2007, 2008, and 2009. Belowground and aboveground tissues of smooth cordgrass plants from 18 marshes were removed, washed, and assayed for Fusarium spp. to determine if patterns between the incidence of the different species of Fusarium, their virulence on S. alterniflora, root-knot nematodes (M. spartinae), and the health of the marsh could be revealed. There were significantly more colonies of Fusarium growing from plants in SVD sites (6.1%) than in healthy marshes where no SVD was present (