In a study in southern California, five species of palms [king palm (Archontophoenix cunninghamiana), mediterranean fan palm (Chamaerops humilis), queen palm (Syagrus romanzoffiana), windmill palm (Trachycarpus fortunei), california fan palm (Washingtonia filifera)] grown in 1-gal containers were planted in 12 × 12 × 12-inch holes in sandy loam (five species) and in clay loam (two species) with the backfill amended using a commercially available, composted, nitrogen-stabilized douglas fir (Pseudotsuga menziesii) shavings product incorporated at 0%, 25%, and 50% by volume. After 18 months, all palms were fully established. Crown volume, stem diameter, visual quality, quantity of new leaves produced, and percent total nitrogen, potassium, and magnesium in leaves did not differ significantly among the three treatments for all species or among treatments within a species. Thus, in this study there was no benefit from amending the backfill with this type of organic amendment when planting palms.
Palms (Arecaceae) are affected by a variety of pathogens, most of which are fungi. We detail pathogens, host ranges, disease description, diagnosis and epidemiology as well as management for the significant, usually fatal, diseases affecting palms grown in the continental United States and Hawaii. These include fusarium wilt (Fusarium oxysporum f.sp. canariensis) of canary island date palm (Phoenix canariensis), diamond scale (Phaeochoropsis neowashingtoniae), ganoderma butt rot (Ganoderma zonatum), lethal yellowing (Candidatus Phytoplasma palmae subgroup 16SrIV-A), and diseases caused by Nalanthamala (Gliocladium), Phytophthora, and Thielaviopsis. We have omitted the leaf spot and minor blight diseases that often affect palms but pose no long-term consequence to their health and survival. Visual symptoms of lethal palm diseases are often similar, necessitating the isolation or detection of the pathogen with cultural, microscopic, or molecular methods. Management of palm diseases is varied, often requiring in-depth knowledge of the biology of the pathogen and its' infection process. Quarantine, eradication, sanitation, and proper species selection and culture are necessary practices to limit the spread of new and existing diseases of palms in landscapes and nurseries.