Root Rot

Scientific name of pathogen

The pathogens most likely to be associated with root rot of container-grown palms are species of Fusarium, Phytophthora, Pythium, Rhizoctonia and Thielaviopsis.

Hosts

All palms are considered potential hosts of these pathogens.

Distribution

The pathogens are worldwide in distribution. Root rot diseases are more likely to be observed in container-grown palms than in landscape or field-grown palms.

Symptoms/signs

Roots will be soft and mushy and discolored (usually black or brown). It is important to know what is the normal color of roots for a particular palm species, as not all palm roots are necessarily white or light tan in color.

Above-ground symptoms are often observed as iron deficiency, slow growth or no growth, and wilting - all due to a dysfunctional root system.

May be confused with

Iron deficiency is often the result of a dysfunctional root system. So, if iron deficiency is observed, especially in container-grown palms, the roots should be examined.

Additional comments

Primary root rots in the landscape or field nursery are not very common. Normally, when root rots in these situations occur, they are secondary in nature and are a result of root suffocation due to a poorly-drained site (water-logged soils) or being planted too deep. Palms produce massive root systems over time, so finding just a few rotted roots in a field or landscape situation is not a concern.

Container-grown palms are more prone to root rots, but, again, this is usually due to poor cultural practices, such as too much irrigation, poorly drained potting substrates or degraded potting substrates.