Phytophthora cinnamomi
（重定向自Littleleaf disease）
![](/Images/godic/202501/24/Dieback_sign_gnangarra2925.jpg")
![A heath landscape in the Stirling Range, Western Australia, with a dieback-infested valley in the mid ground](/Images/godic/202501/24/Die_back_valley_gnangarra2926.jpg")
![Littleleaf disease in Pinus spp., the tree on the left shows no symptoms of infection while the tree on the right shows stunted leaf growth characteristic of Phytophthora cinnamomi infection](/Images/godic/202501/24/Littleleaf_disease2926.jpg")
Phytophthora cinnamomi is a soil-borne water mould that produces an infection which causes a condition in plants called "root rot" or "dieback". The plant pathogen is one of the world's most invasive species and is present in over 70 countries around the world.