Disease of Red Mangrove (Rhizophora mangle) in Southwest Puerto Rico Caused by Cytospora rhizophorae1

Abstract

A high frequency of dieback and mortality was found in Rhizophora mangle (red mangrove) in coastal mangrove forests of southwest Puerto Rico. Eight plots were established in a variety of mangrove environments to assess the extent and severity of the dieback and mortality. The imperfect fungus Cytorpora rhizophorae was isolated consistently from stem dieback and associated canker tissues. No other pathogenic microorganisms were isolated. Pathogenicity was demonstrated in greenhouse and field inoculation experiments with C. rhizophorae using young R. mangle seedlings. In field studies of seedlings inoculated, mortality was 33 percent, and greenhouse mortality was as high as 50 percent. Cytospora rhizophorae was isolated consistently from diseased mangrove tissue; the fungus was grown in pure culture and then inoculated into healthy red mangroves, causing cankers. Koch'~. postulates were fulfilled by infecting R. mangh with C. rhizophorae, producing disease symptoms, and successfully re-isolating C. rhizophorue from the diseased tissue. This is the first documentation of the pathogenicity of C. rhizophorae associated with mortality in red mangrove. In the coastal mangrove forests of southwest Puerto Rico, C. rhizophorae may play an important role in the frequency of dieback and mortality in R. mangle, producing slow stem diameter growth and causing frequent stem and root wounds.

Marine Phytophthora species can hamper conservation and restoration of vegetated coastal ecosystems

“…Massive disease-driven die-offs of seagrasses [18,19] and mangroves [20,21] illustrate the potential harm to a population as a consequence of an outbreak. For instance, the pathogen Labyrinthula zosterae was the purported pathogen responsible for the loss of up to 90% of the Z. marina beds across the North Atlantic region in the 1930s [19,22], which eventually resulted in the loss of ecological properties such as the rich faunal or waterfowl communities often associated with Z. marina [23,24].…”

A review of factors associated with decline and death of mangroves, with particular reference to fungal pathogens

“…The variability of mangrove ecosystems has attracted the attention of several researchers who have contributed extensively to scientific knowledge about fungi associated with mangrove trees (Alias et al, 2010;Cribb and Cribb 1953 (Barnard and Freeman 1982;Pegg et al, 1980;Stevens 1920;Tattar and Scott 2004;Teas et al, 1982;Wier et al, 2000).…”

“…This is more so when one considers the substantial level of research that is being conducted on mangroves and the efforts being made to protect mangrove areas. A review of the literature on mangroves show disease reports ( Wier et al, 2000). No information was found on the possible impact of fungal pathogens on mangrove recruitment.…”

“…While there have been reports of diseases of mangroves (eg. Barnard and Freeman 1982;Teas and McEwan 1982;Tattar and Scott 2004;Wier et al, 2000) this is a subject that has received relatively little attention. The aim of this review is thus, to contribute to the knowledge of causes involved in the death and decline of true mangrove trees, with an emphasis on diseases caused by fungi.…”

Pseudocercospora mapelanensis sp. nov., associated with a fruit and leaf disease of Barringtonia racemosa in South Africa

“…Despite their importance there have been relatively few studies to consider the impact of microbial diseases on these trees (Osorio et al 2014). Diseases that have been reported from mangroves include branch cankers, leaf spots and die-back of trees (Barnard and Freeman 1982;Teas et al 1982;Wier et al 2000;Tattar and Scott 2004;Osorio et al 2014).…”