Susceptibility of Plant Species in Coastal Dune Vegetation of South-western Australia to Killing by Armillaria luteobubalina

Abstract

Estimates of the susceptibility of plant species of coastal dune vegetation tokilling by Armillaria luteobubalina Watling & Kilewere obtained from the occurrence of mycelial sheaths of the pathogen beneaththe bark of the root collars of dead plants in 62 disease centres.Dicotyledons (Magnoliopsida) outnumbered monocotyledons (Liliopsida), being81% of the 330 plant species found in disease centres in coastalvegetation. Fifty-one percent of the species were from five Magnoliopsidafamilies with the largest number of species from the Myrtaceae and Proteaceae.Eleven percent of the species were from three Liliopsida families with thelargest number of species from the Cyperaceae. Thirty-four percent of speciesoccurred in three or more disease centres. Thirty-eight percent, or a total of125 of all species, were killed by A. luteobubalina incoastal vegetation. Hosts on which the pathogen did not reach the root collarwould not have been detected. The largest number of species killed were fromthe Proteaceae (26% of species killed) followed by Myrtaceae,Epacridaceae, Papilionaceae and Mimosaceae. Only 6% of species killedwere from the Liliopsida. The distribution of species frequency and thosekilled by infection is positively skewed, with 40% of species notkilled in any centre and 8% killed in greater than 75% of thecentres in which they occurred. The percentage of disease centres in which aspecies occurred and was killed by A. luteobubalina issignificantly linearly correlated with mortality rating and relativeimportance. Cross-tabulation of species by disease centres in which plantswere killed provided the opportunity to classify the relative susceptibilityof plant species to killing by A. luteobubalina.