LESION DEVELOPMENT IN SEEDLINGS OF JARRAH EUCALYPTUS MARGINATA FOLLOWING STEM INOCULATION WITH PHYTOPHTHORA CINNAMOMI P CITRICOLA AND P CRYPTOGEA
K.L. Bayliss, M.J.C. Stukely, K. Sivasithamparam
Seedlings of ten half-sib jarrah (Eucalyptus marginata) families were stem-inoculated with either Phytophthora cinnamomi A2, P. citricola or P. cryptogea A2 to determine their reaction to these pathogens. Longitudinal and tangential spread of lesions and their appearance were recorded over a period of 42 days and compared between families and between Phytophthora species. There was a continuous range in lesion length across families for each Phytophthora species. Most plants inoculated with P. citricola and P. cryptogea had longer lesions and faster rates of lesion development than those inoculated with P. cinnamomi (P < 0.05). There were no significant differences in tangential spread of lesions between families or between Phytophthora species. Resistance to P. cinnamomi (expressed as short lesion length) did not necessarily indicate resistance to the other Phytophthora species. Further research is needed to determine whether assessment of resistance after stem inoculation of jarrah seedlings with P. citricola and P. cryptogea correlates with field resistance, as has been shown with P. cinnamomi.