Scientific name: Phytophthora spp.
Common Names
Phytophthora root rot, Dieback, Root rot
Phytophthora root rot is a destructive soil-borne disease caused by several species of Phytophthora, most commonly Phytophthora cinnamomi. Although often referred to as a fungus, it is actually a water mould (oomycete) that infects plant roots, restricting the uptake of water and nutrients. It affects hundreds of native and ornamental plants across Australia and is particularly damaging in Western Australia, where it is commonly known as dieback.
The disease spreads through contaminated soil, water, machinery, footwear, and infected nursery stock. It thrives in poorly drained or waterlogged soils and is most active during periods of prolonged moisture and mild temperatures.
Common symptoms include:
- Wilting despite moist soil
- Yellowing or pale foliage
- Stunted growth and reduced vigour
- Branch dieback
- Dark, decaying feeder roots
- Plant death in severe cases
Similar Diseases
- Pythium root rot (Pythium spp.)
- Armillaria root rot (Armillaria luteobubalina)
- Root damage caused by drought or waterlogging
SCENARIOS AND SOLUTIONS
Dieback affected native gardens and bushland restoration sites: Apply Phos-Inject 200 Fungicide as a foliar spray or trunk injection (where appropriate) to help protect susceptible plants and slow disease progression.
Ornamental landscapes with poorly drained soils: Improve drainage, reduce excessive irrigation, and treat susceptible plants with Phos-Inject 200 Fungicide as part of an integrated disease management program.
Nurseries and newly established landscapes: Prevent the introduction and spread of Phytophthora by using disease-free planting stock, maintaining strict hygiene, disinfecting tools and equipment, and applying Phos-Inject 200 Fungicide preventatively where disease pressure is high.
Fruit trees and high-value ornamental plantings showing early decline: Remove severely infected plants where necessary, improve soil drainage, and apply Phos-Inject 200 Fungicide to protect healthy plants and minimise further spread.
