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Phytophthora root rot

What is Phytophthora root rot?

Diseased plants will commonly be found in heavy clay and poorly drained soils within the landscape. Affected plants will exhibit reduced vigor and growth then yellowing of the leaves followed by wilting before rapidly turning brown resulting in plant death. Infected trees may decline slowly over a several year period or they may suddenly wilt and die rapidly after the first warm weather period.

What causes Phytophthora root rot?

 This soil-borne fungus survives in infected wood or as thick walled resting spores. These spores can survive for long periods of time (many years). Then when the soil is saturated with water the thick-walled spores germinate to produce swimming spores. These spores swim thru soil water infecting susceptible small root tissue or by splashing water and infecting branches or leaves. The swimming spores can be spread long distances by surface water runoff or by spread of contaminated soil or plants. After root infection, the fungus grows and spreads throughout the inner bark of the roots and into the lower stem killing the plant tissue.

What can be done with Phytophthora root rot

If you think you have a tree or shrub with root rot, make sure you are providing just enough water without saturating the soil and then contact us to verify and help make recommendations and treatments. A tree demonstrating phytophthora root rot symptoms can sometimes be saved by using specialized equipment such as air spades to remove the soil from around the base of the tree all the way down to the top of the main roots, cutting away any bark that’s oozy or dark and leaving the root system exposed. This allows the root system to dry completely, slowing the spread of phytophthora root rot. We can also treat using a soil fungicide which will sterilize the spores allowing the roots to rejuvenate. Repeated applications may be necessary depending on the severity of disease present.


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