Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Pathogenicity of Pythium spp. and Phytopththora drechsleri to Eucalyptus spp.

Abstract

The pathogenicity of Pythium ultimum (a), P. iregulare (b), P. debaryanum (c), P. vexans (d), P. mamillatum (e), of three unidentified Pythium spp. from Eucalypt forest soil and of Phytophthora drechsleri, were compared with that of P. cinnamomi in inoculation tests on potted juvenile and intermediate-aged (5 months old) seedlings of Eucalyptus sieberi and juvenile seedlings of other Eucalypts. Of the Pythium species, only (a), (b) and (c) killed small juvenile seedlings at the two-leaf stage of development, and none of these species, nor P. drechsleri, could kill E. sieberi at the intermediate growth stage. In marked contrast, P. cinnamomi showed considerable pathogenicity, killing seedlings and saplings rapidly. The unidentified Pythium spp. from native forests were completely innocuous.<new para>ADDITIONAL ABSTRACT:<new para>The pathogenicity of Pythium ultimum, P. irregulare, P. debaryanum, P. vexans, P. mammillatum, 3 unidentified P. spp. from Eucalyptus forest soil and Phytophthora drechsleri was compared with that of P. cinnamomi on juvenile and intermediate aged seedlings of E. sieberi and juvenile seedlings of other E. spp. Of the Pythium spp., only P. ultimum, P. irregulare and P. debaryanum could kill small juvenile seedlings at the 2 leaf stage. Neither the Pythium spp. nor Phytophthora drechsleri could kill E. sieberi at the intermediate growth stage. In marked contrast P. cinnamomi showed considerable pathogenicity, quickly killing seedlings and saplings. The unidentified Pythium spp. were completely innocuous.