Guide to Palm Diseases

Palms are, in general, very resistant trees to bad weather, salinity and even pests and diseases. Pests associated with palms, such as the red palm weevil or weevils, are generally better known.

However, there is a list (short, yes) of palm diseases that can affect its development or, in the worst conditions, bring it to an abrupt end.

These fungi are not very common and usually appear in conditions of high humidity or waterlogged soil.

Let’s find out what are the main palm diseases.

List of palm diseases

  • Wilting of palm trees: Fusarium oxysporum F.sp. Bayoud canariensis
  • Helminthosporium: Helminthosporium bipolar.
  • Pink rot: Gliocadium vermoesenii Biurge Thom.
  • Fake rust: Graphiola phoenicis Djerbi.
  • Leaf spot: Pestalotiopsis palmarum Cook Steyaert.
  • Stem slime and black heart rot: Thielaviopsis paradoxa De Seynes Höhn and Ceratocystis paradoxa.

Wilting of palm trees: Fusarium oxysporum F.sp. Bayoud canariensis

Fusarium wilt of palmsPhotography: Monica Elliott, University of Florida.

Symptoms

Of all the palm diseases, wilt (Fusarium oxysporum) is ranked among the most serious for this type of crop.

Visually, the externals are seen with some degree of wilting and downward tilt. Above them you can see a localized dryness on one side of the leafsince this fungus has a lateral projection.

Usually, the first symptoms of this palm disease usually appear on the oldest leaves, located on the outer ring.

Initially, yellow spots appear on one side of the palm, but it dries quickly (brown colors).

affected palms

This disease can appear in a wide range of palms, the main one being canary palm (phoenix canariensis).

Other varieties have also been diagnosed, such as phoenix dactylifera, lying phoenix, sylvan phoenix Yes Filiferous Washingtonia.

disease control

All control measures for this palm disease are based on Preventive actions.

  • Avoid damaging the roots, as the fungus is found in the substrate.
  • Disinfection of work tools with 0.5-1% bleach solutions or other authorized disinfectants.
  • Reduce stressful conditions, primarily waterlogging and lack of drainage.

Helminthosporium (complex) bipolar

It is known as leaf spot or palm leaf burn.

Symptoms

On the leaves there are spots caused by different groups of fungi, wet in appearance, black or dark brown and with small pustules.

These gradually appearing lesions, initially yellow but slowly darkening, measure between 2 and 10 mm, forming a yellow halo at their border.

Pink palm stain: Gliocladium vermoesenii Biourge Thom

Pink palm stainImage: Monica Elliott, University of Florida.

It is known as pink rot or pink blotch of palms.

Symptoms

Symptoms are observed on the outer leaves (the oldest), dries out completely.

The fungus slowly progresses inward, causing rot in the base area and burrowing into the bud.

When cutting a palm stem, a pink powderaspect which gives the name of this palm disease.

Fake rust: Graphiola phoenicis

fake palm rustImage copyright: Monica Elliott, University of Florida.

Although this disease is present in Spain, there are very few reported cases.

Symptoms of the disease:

This palm disease leaves a very obvious trace of its presence on the leaves. Above them, dark yellow spots appear located on both sides of the petiole. These spots are in the form of pustules and protrude from the leaf.

Since the incubation time of the fungus is about 10 months, the disease is usually observed in the 2nd year of infection.

State: it roughly halves the lifespan of palm fronds.

Palms affected: genera Phoenix, Chamoerops, Washingtonia, Roystonea, Kentia, Butia, Arenga, Cocos, Livistona, etc.

leaf spot (Pestalotiopsis palmarum Cooke Steyaert)

Pestalotiopsis palmarum palmsSource: uprm.edu – Agricultural Extension Service.

The common name for this palm disease is leaf spotsince it manifests itself on the leaves of the palm trees.

Palm symptoms:

Black spots of small appearance and circular geometry appear on the leaves. As the fungus infection progresses, these lesions enlarge and appear white with well-defined black borders.

In the central area of ​​the wounds, fruiting bodies of this fungus can be observed. It can affect tissues that have already been affected by other more aggressive pathogens.

Conditions that favor it:

  • High ambient humidity and tropical areas. yes
  • Waterlogged or poorly drained soil conditions. or poorly drained soil mixes. Bad management of palm trees.

Palms affected: palmaceas in general, especially in date palms, the Canary Islands and Washington.

Stem slime and black heart rot

Thielaviopsis paradoxa palmPhotography: Monica Elliott, University of Florida.

Causal agent: the fungus has two phases: the superior or anamorphic Thielaviopsis paradoxa and the final form, the mushroom Ceratocystis paradox.

Symptoms: At the onset of the disease, a yellowish soft rot is formed. As the disease progresses, the affected areas become discolored and darken with age.

At the end, a reddish liquid exudation is observed, which ceases to exude in old lesions, becoming darker or black. The infection inside the wounds can be much more extensive.

The heart of the palm, with its terminal bud and the base of the youngest leaves, at an advanced stage, can also blacken, rot and even cause the death of the plant.

The fungus enters the interior of the palm through natural processes or through wounds caused by animals or mechanical damage.

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