SUSCEPTIBILITY OF PLANT-SPECIES IN COASTAL DUNE VEGETATION OF SOUTHWESTERN AUSTRALIA TO KILLING BY ARMILLARIA-LUTEOBUBALINA

Estimates of the susceptibility of plant species of coastal dune veget ation to killing by Armillaria luteobubalina Watling & Kile were obtai ned from the occurrence of mycelial sheaths of the pathogen beneath th e bark of the root collars of dead plants in 62 disease centres. Dicot yledons (Magnoliopsida) outnumbered monocotyledons (Liliopsida), being 81% of the 330 plant species found in disease centres in coastal vege tation. Fifty-one percent of the species were from five Magnoliopsida families with the largest number of species from the Myrtaceae and Pro teaceae. Eleven percent of the species were from three Liliopsida fami lies with the largest number of species from the Cyperaceae. Thirty-fo ur percent of species occurred in three or more disease centres. Thirt y-eight percent, or a total of 125 of all species, were killed by A. l uteobubalina in coastal vegetation. Hosts on which the pathogen did no t reach the root collar would not have been detected. The largest numb er of species killed were from the Proteaceae (26% of species killed) followed by Myrtaceae, Epacridaceae, Papilionaceae and Mimosaceae. Onl y 6% of species killed were from the Liliopsida. The distribution of s pecies frequency and those killed by infection is positively skewed, w ith 40% of species not killed in any centre and 8% killed in greater t han 75% of the centres in which they occurred. The percentage of disea se centres in which a species occurred and was killed by A. luteobubal ina is significantly linearly correlated with mortality rating and rel ative importance. Cross-tabulation of species by disease centres in wh ich plants were killed provided the opportunity to classify the relati ve susceptibility of plant species to killing by A. luteobubalina.