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

Abstract

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 (<1.0%). The incidence of Fusarium spp. from plants at the perimeter of the SVD site was not statistically different from asymptomatic plants 10-20 m from the SVD edge.

Indirect effects of non‐native Spartina alterniflora and its fungal pathogen (Fusarium palustre) on native saltmarsh plants in China

“…In this study, we explored the indirect effects of non‐native Spartina involving a pathogen associated with dieback on native Phragmites in Chinese saltmarshes. Fusarium palustre was confirmed as the endophytic fungus in the Dongtan wetland as being the same pathogen driving Spartina alterniflora dieback in North American saltmarshes according to morphological traits and phylogenetic relationships (Elmer, LaMondia & Caruso ; Elmer & Marra ).…”

Plant response to fungal root endophytes varies by host genotype in the foundation species Spartina alterniflora

“…Previous studies of the effects of root‐associated fungi on S. alterniflora have demonstrated the potential for widespread negative effects. For instance, Fusarium spp., a putative fungal pathogen, was consistently found at sites where S. alterniflora was experiencing dieback, yet it did not cause mortality of healthy plants in the greenhouse (Elmer et al, 2012). Subsequent experiments demonstrated that Fusarium had negative effects on S. alterniflora when in combination with drought stress and that herbivory was higher on drought‐stressed, inoculated plants than healthy plants (Elmer, 2014).…”

Six novel species of Fusarium from natural ecosystems in Australia

“…The closest described species are F. langsethiae (origin: Europe), F. palustre (origin: USA) and F. sibiricum (origin: Russia). It is interesting that F. goolgardi was associated with Xanthorrhoea decline that was symptomatically similar to the dieback associated with F. palustre in the USA (Elmer and Marra 2011;Elmer et al 2012). Trichothecenes are involved in plant pathogenesis (Proctor et al 2002;Desjardins and Hohn 1997) and given that F. goolgardi clusters in a trichothecene producing clade it would be valuable to determine if it produces trichochenes, which may have a role in Xanthorrhoea decline at the Bungonia National Park site.…”