Phytophthora dieback occurs throughout the south west of WA under varying climatic, vegetation, and soil conditions. The human and environmental variables associated with its spread, impact and management have a spatial context across our vulnerable landscapes. The important collation of influencing variables as spatial information helps to better understand Phytophthora dieback distribution, impact, and management requirements.

Phytophthora dieback spatial information can be collated by people who:

  • Have a general passion for the environment but have limited formal expertise or training,
  • Are highly trained DPaW accredited dieback interpreters, and
  • Are non-accredited interpreters who offer expertise in other relevant disciplines?

As part of Project Dieback a number of spatial information technology (MAPPING) tools have been developed to support Dieback stakeholders with basic to advanced dieback management and planning needs. These MAPPING tools provide a framework for standardising the collection, collation, management and sharing of Phytophthora dieback information.

Project Dieback MAPPING Tools include:

posumm-iconDieback Public Map

DIDMS (Dieback Information and Delivery Management System)

The acronym DIDMS means “Dieback Information Delivery Management System” and GRID means “Geographic Reporting Information Database”. DIDMS GRID is a user registered web based platform for storage, viewing, basic mapping and sharing of spatial Phytophthora dieback information by intermediate level users.

DIDMS GRID is developed and hosted by Gaia Resources Pty in association with South Coast NRM.

To register for a free DIDMS user account click on the following link > posumm-icon CLICK HERE

For existing DIDMS users click on the following DIDMS login link > posumm-icon DIDMS login.

What can you do with DIDMS GRID?


DIDMS GRID provides South Coast NRM and partner organisations with a consistent and user friendly mechanism to online record, store, share and map Dieback work across the region using standardised data capture methodology. DIDMS provides a spatial data framework to:
  • Report on the status of Phytophthora dieback throughout WA;
  • Manage Phytophthora dieback information;
  • Support users to share Phytophthora dieback information.
  • Provide a basic spatial Phytophthora dieback platform for landscape and area planning.
grid didms-2

Plant Disease Data

The following information is provided as a guide to what plant disease information is available in DIDMS and how to in part use this information.

Disease Point data

Since 1982, the Department of Parks and Wildlife Vegetation Health Services (VHS) have been analysing field samples in a laboratory for presence or absence of Phytophthora disease, and recording these results into a Phytophthora database.

There are five species of Phytophthora data collated by VHS that have been converted into a GIS format and uploaded to DIDMS as Baselayers. The datasets are updated to June 30 each calendar year.   The Phytophthora meta data report outlines scale and accuracy of the VHS data presented in DIDMS.

DIDMS Baselayers:

Disease points across all land, course scale; includes private property data, and the DIDMS user cannot zoom in beyond a certain scale. The data will disappear when the user zooms in beyond the privacy scale setting.

Disease points on public land only, fine scale; includes positive VHS data collected on public lands and can be zoomed to a very high resolution. The Disease points on public lands baselayers and associated met data reports are available for download within DIDMS by registered users.

Soil borne Phytophthora:
  1. P. cinnamomi    Pc pnt DIDMS                Dis pnts DIDMS
  2. P. multivora      Pm pnt DIDMS             
  3. P. inundata       Pi pnt DIDMS               
  4. P. nicotianae     Pn pnt DIDMS        
  5. P. pseudocryptogea  Ppcryp pnt DIDMS      
These Phytophthora spread via soil movement by:
  • Vector Spread - humans (Roads, tracks, trails, rail, utility corridors, mining, and associated economic, recreational, cultural activities) and animals; and
  • Autonomous spread – root to root contact and hydrology surface and subsurface flow (Rivers, streams, run-off from sheading slopes).
Airborne Armillaria:

      6. Armillaria luteobubalina

Armillaria data is collated by VHS separate to the Phytophthora database. A luteobalina is a native species of plant pathogen which is predominately dispersed naturally by wind. Spores are released from mushroom fruiting bodies during wet summer periods, autumn or spring. The disease normally becomes established when wind transported spores settle on freshly damaged plant wounds. The disease can also spread by transporting infected plant material such as vegetation stuck to slashers, and transporting infested mulch. Once established, the disease then moves root to root.


It is important to note that VHS “negative” sample points do not necessarily confirm the absence of Phytophthora. There is a degree of uncertainty with “negative” sample points which can result in a “false negative”. “False negative” uncertainty is reduced, but not eliminated, when a registered Phytophthora Dieback Interpreter undertakes the sampling. The chances “positive” samples resulting in a “false positive” are less likely when appropriate sampling techniques and hygiene are applied.

Phytophthora cinnamomi interpreted data

The professional standard for Phytophthora Dieback disease mapping is specific to P. cinnamomi, is set by the Department of Parks and Wildlife and applied through “Registered Phytophthora Dieback Interpreters”. P. cinnamomi disease status data only meets these standards when collected by a registered Phytophthora Dieback Interpreter.
Dis int DIDMS

Disease status categories

The Registered Phytophthora Dieback Interpreter uses standardised diagnostic techniques supported by VHS sampling to map the following disease status categories for P. cinnamomi:
  1. Infested Inf DIDMS – Symptoms of Phytophthora Dieback disease are visible
  2. Uninfested Uninf DIDMS – An area that a registered interpreter has determined may be free of plant disease symptoms that indicate the presence of the pathogen P. cinnamomi
  3. Uninterpretable Uninterp DIDMS – Areas of natural undisturbed vegetation where susceptible plants are too few for interpretation of Phytophthora Dieback.
  4. Not Yet Resolved NYR DIDMS – Phytophthora occurrence diagnosis cannot be made because of inconsistent evidence.
  5. Temporarily Uninterpretable TempUnint DIDMS – A naturally vegetated area that has had disturbance and likely to recover from that disturbance in the short term.
  6. Excluded Excl DIDMS – An area of high disturbance where natural vegetation is unlikely to recover.
(Department of Parks and Wildlife (DPAW) (2015), Phytophthora Dieback Interpreter Procedures for land managed by the department. WORKING DRAFT 2, Forest and Ecosystem Management Division)


Phytophthora Dieback interpretation data within DIDMS may NOT be comprehensive, up to date, vary in scale and quality. Phytophthora Dieback disease Information is considered current up to 12 months within its survey date capture for Uninfested areas and 3 years for Infested areas. Areas that have not been mapped MAY still be infested, until stated otherwise by a “Registered Phytophthora Dieback Interpreter”. . Refer to DIDMS Data Disclaimers section regarding appropriate use of this data.

Disease Confidence Mapping P. cinnamomi to June 2008

The DIDMS Baselayer: “Disease Confidence Mapping P. cinnamomi to June 2008” data. The Phytophthora disease boundaries and categories portrayed in this dataset are a composite of survey data collected at varying times over 30 years. The dataset comprises various scales of survey intensity and various levels of interpretation confidence. The extent of infestations are underestimated, as not all areas have been surveyed and disease boundaries are likely to extend into mapped disease free areas since surveys were conducted. If a User zooms beyond a datasets scale view setting within DIDMS it will DISAPPEAR from view to part protect the data being used beyond its accuracy of scale capture. The data is not current and Disease Confidence Mapping should be viewed with the overlayed DIDMS “Disease points on Public Lands” dataset. Refer to DIDMS Data Disclaimers section regarding appropriate use of this data.

Phytophthora hazard dispersion area data

This is a decision support tool developed focussing on potential P. cinnamomi hazard dispersion pathways linking known disease point locations using GIS. Phytophthora Hazard Dispersion Models will be conducted across parts of the South West in future pending funding and the map results uploaded to DIDMS. It is the responsibility of the user to interpret model outputs in context with other plant disease information, susceptibility of values threatened and the type of activities being undertaken along hazard pathways linking the values.

The P. cinnamomi hazard dispersion tool was developed as part of Project Dieback. The model is NOT a biological disease occurrence model, but a scenario hazard tool to be used as part of a risk assessment. The tool estimates hazard areas that are geographically linked to a known VHS disease point via spread pathways over time. The model preparation requires expertise to set spread inputs, which include root to root rate of spread; human vector maximum distance spread estimates for roads, tracks, and trails; hydrology stream/river downstream distance dispersion estimates; and the time duration of dispersion scenario in years.

Once inputs are set, the model then runs basic hazard dispersion calculations for the expert disease dispersion estimates based on GIS datasets for VHS disease points, stream, road vectors, and a Digital Elevation Model (DEM). The final modelled P. cinnamomi hazard dispersion mapping outputs are divided into five even categories (pentiles) according to an areas distance from a known disease point and associated pathway. The pentile categories are assigned a Hazard rating of:

1 = Extreme    Haz Ex DIDMS                  Haz DIDMS
2 = Very High   Haz VH DIDMS                
3 = High          Haz H DIDMS                  
4 = High-Moderate  Haz HM DIDMS       
5 = Moderate          Haz M DIDMS        

Risk Assessment - Soilborne Phytophthora

Through Project Dieback, this risk based approached draws on understanding values, assets, threats, hazards, management objectives, management strategies and feasibility assessment. The hazard component of this risk model was the impetus to develop a GIS P. cinnamomi Hazard Dispersion tool to help link the hazard of a known threat to a susceptible biodiversity value.

Risk = Threat x Vulnerability (Susceptibility + Hazard) x Consequence (Impact)

Components of this risk model for the purposes of soil borne Phytophthora planning are defined as:
  • Risk - The chance that a Plant Disease threat will result in the impact of vulnerable values/assets to the point where the consequence results in goal/objective failure.
  • Threat - known location, extent and severity of the plant disease on an area and its proximity to uninfested susceptible areas;
  • Susceptibility - level of a species, community, ecosystem, or landscape resilience to plant disease impact;
  • Hazard - pathways and activities that link a known plant disease locations to an uninfested susceptible area (includes environmental hazard: wet soil, soil type, slope, landform, climate);
  •  Vulnerability - the sum of the susceptibility and hazards in an area; and
  •   Impact - impact of the disease on a plant, community, ecosystem, landscapes, species composition, structure, and function. This impact is then translated to human value being a consequence.

DIDMS Data Disclaimers

  1. The data in DIDMS is suitable for general overview, general scoping, broad scale planning (>1:100,000), and educational purposes.
  2. The data is NOT suitable for operational or environmental impact assessment purposes within DIDMS.
  3. It is the responsibility of the DIDMS user to acquire permission from the custodian/owner of the data presented within DIDMS to use beyond the conditions outlined in this disclaimer.
  4. The ONUS of data quality is with the DIDMS User when uploading data.
  5. It is the responsibility of the DIDMS user to acquire permission from the client and/or landholder prior to uploading Phytophthora Dieback disease data collected on their clients, or first party’s behalf.
  6. a) Ownership and custodianship of uploaded DIDMS data is the responsibility of the DIDMS user to define.

DIDMS; Register a User Account

Users are required to register with the DIDMS Administrator in order for an User account to be set up. Once your account has been set up by the Administrator you will recieve an email letter with your user name, password, user type (External or Internal) and Privacy Disclaimer. If you would like to be a part of the DIDMS Please email the administrator your: