Abstract
Paulownia spp. are deciduous trees famed for their rate of growth. They are relatively new plantation species in Western Australia. In October 2001 a severe disease was observed on Paulownia trees in WA plantations. Early in the season the disease causes black leaf lesions, while later in the season the disease causes light brown leaf lesions. Infections often started at the leaf tips and progressed to the base of the leaves as symptoms developed. In addition, discoloured sunken cankers were observed on the trunk, branches and petioles of many trees. Canker symptoms include oval sunken regions. The stem or trunk may die distal to the canker while the tree often remained healthy below the canker. This disease is capable of killing 3-5 year old trees in the field. The pathogen was isolated from symptomatic leaves, petioles and trunks. The pathogen was identified as A. tenuissima by DNA sequencing of the rDNA, and by morphological examination of the three-dimensional sporulation pattern. Koch's postulates were demonstrated by glasshouse inoculation of 6-mth old potted Paulownia trees. Stem and leaf disease symptoms were observed and A. tenuissima was re- isolated. This is the first report of A. tenuissima causing disease of Paulownia.