Phytophthora crown rots
Phytophthora cactorum, P. citricola, P. parasitica, and P. megasperma
P. cactorum is the most common species of Phytophthora isolated from strawberries in Western Australia.
Plants initially appear stunted with small leaves. As the disease progresses, plants eventually collapse. When infected plants are cut open, a brown discoloration can be seen in the crown.
Effective soil fumigation and the use of clean planting material are important. Soil should be well drained, using raised beds and properly scheduled irrigation. If the disease is in the early stages, or to prevent spread to other plants, foliar sprays of phosphorus acid may help.
Other crown rots
Macrophomina phaseolina, Gnomoniopsis comari
Macrophomina and Gnomoniopsis have been isolated to a lesser extent from the crowns of collapsed strawberry plants. They often occur with other pathogens.
Gnomoniopsis can exist as a systemic infection in runners which is not noticed until conditions are favourable and it begins to infect leaves and calyces (see Gnomoniopsis web page).
Rhizoctonia root rot
Rhizoctonia is the most commonly isolated root rot pathogen in strawberries. It often occurs in combination with other pathogens such as Fusarium and Phytophthora and is seldom a problem in its own right.
Other root rots
Pythium spp., Phytophthora cactorum and Cylindrocarpon destructans
Cylindocarpon destructans has been isolated frequently from plants affected by root rot and to a slightly lesser extent, Phytophthora cactorum and Pythium ultimum.
C. destructans is usually considered to be a weak pathogen when it occurs alone,however, in sandy soils, pathogen complexes causing root disease are common and it is possible that these individual pathogens may assume greater significance when present together.