Phytophthora Root Rot
Jarrah Die Back
A fungal disease that attacks the root system of trees.
Leaves turn yellow and die and branches die back from the tips. The plant usually dies after a period of hot weather puts it under severe water stress because of its damaged root system. Portions of a tree may die if only a portion of the root system is infected.
There are few root hairs or fine roots and the fine roots are usually brown and brittle.
Canola and Clover:Infected roots have a dark discolouration and are decayed. Plants can be easily pulled from the ground. Often occurs in patches especially in wet areas and poorly drained heavy soils.
Species Affected:Avocadoes, Banksias, Canola, Clover, Eucalypts, Kiwi Fruit, Proteas
Biology:It can't infect Macadamia through the root system but enters through wounds in the trunk, causing trunk canker that has discoloured and oozing gum.
Spread in mud and running water.
Often spread in pot plants.
Life Cycle:Origin and History:
Management and Control:
Test soil for Phytophthora before planting.
Redirect water flows from infected areas, bushland and roads away from crop.
Avoid bringing contaminated soil into cropping area on machinery.
Purchase stock from clean nurseries.
Place fungicidal footbaths at the entrance to the cropping area.
Improve drainage. Avoid over watering.
Use straw mulches around trees but don't let them contact the bark.
Remove and destroy infected plants.
Avoid wounding trunks of Macadamia.
Plant tolerant clover varieties. See Disease Susceptibility of Clover Varieties.
Related and Similar Species:References:
(Marcroft et al., 2002)
Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.