How to Identify Phytophthora cinnamomi Infection in Tasmania
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There are many diseases which occur in native vegetation and the majority of these are natural events which play an important ecological role. The patterns of disease expression in time and space as well as the species affected and dieback symptoms need to be assessed to identify potential
Phytophthora cinnamomi infestations. Conclusive identification of
P. cinnamomi as the cause of disease requires analysis of soil or root samples in a laboratory.
Good indicators for recent or active
P. cinnamomi
are:
-
Death or disease in known susceptible species (note: not all individual plants will be attacked simultaneously in a diseased area)
-
Diseased plants show discolouration of the foliage, most commonly reds and yellows
-
Known resistant species remain healthy
-
There is a temporal sequence of disease across a site (e.g. the oldest death in the center or towards the uphill end of infections on slopes)
-
Sharp disease fronts or boundaries between healthy and diseased vegetation may be present
To verify symptom based assessments, soil and plant material should be sampled and analysed for the presence of the pathogen. As
P. cinnamomi can be difficult to successfully isolate, expert assistance should be sought when sampling is required.
The age of infection and degree of disease activity will affect the ability to successfully interpret the presence of
P. cinnamomi at a site. Careful observation is required to identify old or inactive infected sites, particularly if the majority of susceptible plants have disappeared.
It is also desirable to monitoring a site over a period of time to assist with identifying sites which are difficult to interpret e.g. recently burnt.
This periodicity in disease activity will probably be most evident where host species presence, soil moisture and temperature conditions fluctuate between favourable and unfavourable during or between years.
The following tables list the common indicator species for
P. cinnamomi in Tasmania. The susceptible species column presents those species for which mortality is expected within infected areas. The resistant species column lists those species that should remain healthy within infected areas.
Table 1: Table of indicator species for Moorland Vegetation
P. cinnamomi Susceptible species |
P. cinnamomi Resistant species |
---|
Agastachys odorata |
Baumea spp. |
Baeckea leptocaulis |
Ehrharta spp. |
Banksia marginata |
Empodisma minus |
Blandfordia punicea |
Gymnoschoenus sphaerocephalus |
Boronia spp. |
Helichrysum pumilum |
Cenarrhenes nitida |
Lepidosperma filiforme |
Dillwynia glaberrima |
Leptocarpus tenax |
Epacris corymbiflora |
Leptospermum scoparium |
Epacris lanuginosa |
Melaleuca squarrosa |
Melaleuca squamea |
Sporadanthus tasmanica |
Sprengelia incarnata | |
Stylidium graminifolium | |
Table 2: Table of indicator species for Heathland Vegetation
P. cinnamomi Susceptible species |
P. cinnamomi Resistant species |
---|
Amperea xiphoclada |
Acacia spp. |
Aotus ericoides |
Allocasuarina littoralis |
Astroloma spp. |
Comesperma spp. |
Baeckea leptocaulis |
Empodisma minus |
Banksia marginata |
Hypolaena fastigiata |
Blandfordia punicea |
Kunzea ambigua |
Boronia spp. |
Lepidosperma spp. |
Dillwynia spp. |
Leptocarpus tenax |
Epacris spp. |
Leptospermum scoparium |
Hibbertia spp. |
Lomandra spp. |
Leucopogon collinus |
Melaleuca squarrosa |
Leucopogon ericoides |
Pimelea spp. |
Melaleuca squamea |
Spyridium spp. |
Persoonia gunnii | |
Phyllota diffusa | |
Pultenaea spp. | |
Sprengelia incarnata | |
Stylidium graminifolium | |
Tetratheca spp. | |
Xanthorrhoea spp. | |
Table 3: Table of indicator species for Open forest Vegetation
P. cinnamomi Susceptible species |
P. cinnamomi Resistant species |
---|
Allocasuarina monilifera |
Acacia spp. |
Amperea xiphoclada |
Allocasuarina littoralis |
Aotus ericoides |
Allocasuarina stricta |
Astroloma humifusum |
Bedfordia spp. |
Banksia marginata |
Cassinia aculeata |
Blandfordia punicea |
Comesperma spp. |
Boronia spp. |
Exocarpos cupressiformis |
Dillwynia glaberrima |
Gahnia grandis |
Epacris spp. |
Kunzea ambigua |
Hibbertia spp. |
Lepidosperma spp. |
Leucopogon collinus |
Leptospermum scoparium |
Leucopogon ericoides |
Lomandra spp. |
Melaleuca squamea |
Melaleuca squarrosa |
Monotoca submutica |
Olearia spp. |
Oxylobium spp. |
Pimelea spp. |
Persoonia gunnii |
Zieria arborescens |
Pultenaea spp. | |
Stylidium graminifolium | |
Tasmania lanceolata | |
Tetratheca spp. | |
Xanthorrhoea spp. | |
Tables modified from: Podger, F. Palzer, C. & Wardlaw, T. A. (1990). Guide to the Tasmanian Distribution of Phytophthora cinnamomi and its Effects on Native Vegetation.
Tasforests, vol 2, no.1, Forestry Commission of Tasmania, Hobart.