Phytophthora cinnamomi is a soil-borne water mould that produces an infection which causes a condition in plants variously called "root rot", "dieback", or (in certain Castanea species), "ink disease". The plant pathogen is one of the world's most invasive species and is present in over 70 countries around the world. Host range and symptoms The host range for Phytophythora cinnamomi is very broad. It is distributed worldwide and causes disease on hundreds of hosts. The disease affects a range of economic groups, including food crops such as avocado and pineapple as well as trees and woody ornamentals such as Fraser firs, shortleaf pines, loblolly pines, azaleas, camellia, boxwood, causing root rot and dieback. It is a root pathogen that causes root rot and death of host plants. Some symptoms include: wilting, decreased fruit size, decrease in yield, collar rot, gum exudation, necrosis, leaf chlorosis, leaf curl, and stem cankers. Another symptom is that it can cause dieback of young shoots and may interfere with transpiration of roots to shoots. Older plants may not exhibit symptoms or may display only mild dieback despite having severe root rot. Life cycle and effects on plants Phytophthora cinnamomi lives in the soil and in plant tissues, can take different shapes and can move in water. During periods of harsh environmental conditions, the organisms become dormant chlamydospores. When environmental conditions are suitable, the chlamydospores germinate, producing mycelia (or hyphae) and sporangia. The sporangia ripen and release zoospores, which infect plant roots by entering the root behind the root tip. Zoospores need water to swim through the soil, therefore infection is most likely in moist soils. Mycelia grow throughout the root absorbing carbohydrates and nutrients, destroying the structure of the root tissues, "rotting" the root, and preventing the plant from absorbing water and nutrients. Sporangia and chlamydospores form on the mycelia of the infected root, and the cycle of infection continues to the next plant. Early symptoms of infection include wilting, yellowing and retention of dried foliage and darkening of root color. Infection often leads to death of the plant, especially in dry summer conditions when plants may be water stressed. Environment Phytophthora cinnamomi is a soil-borne pathogen first reported in tropical and subtropical countries, but is now found to be able to survive and develop in cooler countries as well. P. cinnamomi is spread as zoospores and/or chlamydospores in soil and water are placed in