SUSCEPTIBILITY OF PLANT-SPECIES IN BANKSIA WOODLANDS ON THE SWAN COASTAL-PLAIN, WESTERN-AUSTRALIA, TO INFECTION BY PHYTOPHTHORA-CINNAMOMI

Estimates of the susceptibility of plant species in Banksia woodland t o Phytophthora cinnamomi Rands were obtained by determining the incide nce of plant death and frequency of isolation of the pathogen, among s pecies occurring in 46 disease centres on the Swan Coastal Plain south of Perth, Western Australia. In the disease centres, dicotyledons out numbered monocotyledons. About half of all species occurring in the di sease centres were from four families of dicotyledons, with the larges t number of species from the Myrtaceae, Proteaceae and Papilionaceae. The greatest number of species of monocotyledons were from the Antheri caceae and Cyperaceae. No deaths were recorded for 47% of species foun d in three or more disease centres. These species were mainly from the Cyperaceae, Haemodoraceae, Myrtaceae and Papilionaceae. The species t hat tended to die frequently in disease centres were mainly from the P apilionaceae, Proteaceae, Epacridaceae, Xanthorrhoeaceae and the Zamia ceae. Phytophthora cinnamomi was isolated from 26 of the 95 species oc curring in three or more disease centres. For most species, the freque ncy of isolation of P. cinnamomi from recently dead plants was much le ss than the frequency of dead plants sampled. Isolation from plants wa s less frequent than from adjacent soil. The pathogen was isolated fro m recently dead plants or soil mainly for species of the Proteaceae, M yrtaceae, Papilionaceae, Dasypogonaceae, Iridaceae and Xanthorrhoeacea e. Cross-tabulation of species by incidence of plant death and isolati on of P. cinnamomi from plant and soil, provided the opportunity to cl assify the response of plant species to infection by P. cinnamomi.