Diseases

Fusarium Wilt-Canary Island Date⎮ Fusarium Wilt-Queen & Washingtonias⎮Ganoderma Butt Rot ⎮ Graphiola Leaf Spot ⎮ Lethal Bronzing Disease ⎮ Petiole Blight ⎮ Thievalopsis Trunk Rot

What Happens: The fungus Fusarium oxysporum f. sp. canariensis compromises the vascular tissues of the palm. Fusarium wilt is primarily transmitted through contaminated pruning tools. It is often spread from palm to palm in the landscape.

Symptoms: The fronds die from the bottom up more rapidly than normal.  One sided death of the frond is a symptom, however, this is transitional and is sometimes hard to find on an infected palm. It is believed that a palm can be infected with Fusarium wilt for 6-18 months before symptoms become apparent. 

Susceptible Palms:  Phoenix canariensis (Canary Island Date Palm). Occasionally, but rarely Phoenix dactylifera, Phoenix sylvestris, and Phoenix reclinata palms.

Can Be Confused With: Petiole and rachis blight.

Preventative Measures: There is no cure or treatment for this fungus.  Therefore, the best solution to prevent this disease is to make sure either a new pruning tool is used on each palm, or the pruning tools are sterilized before pruning each palm.  The fungus will not infect a palm through dead material.  Therefore, only completely dead fronds should be removed when trimming susceptible palms.

Solution: Only hire a knowledgable professional to trim your palms.

Fatality: This disease is fatal.  The disease can translocate into the roots and soil, so it is not advisable to plant the same species back into a diseased palm’s location.

More Information: https://plantpath.ifas.ufl.edu/misc/media/factsheets/pp0044.pdf

What Happens: The fungus Fusarium oxysporum f. sp. palmarum compromises the vascular tissues of the infected palm.

Symptoms: The fronds die from the bottom up very rapidly. Then the palm dies.  One sided death of the frond is also a symptom of this disease.  However, this is a transitional symptom and in just a few days this frond can turn completely brown.  The spear leaf is the last frond to die.  The decline is so rapid, that the majority of the fronds usually die in about 6-12 weeks.  However, death in the majority of the canopy can occur in as fast as one week.  The fronds die so fast, they don’t have the wilted look like you will see with Ganoderma.  The palm has a “freeze dried” look where the fronds are still upright, but brown.

Susceptible Palms: Syagrus romanzoffiana (Queen Palm), Washingtonia robusta (Mexican Fan Palm).  Occasionally X Butiagrus nabonnandii (Mule Palm) and Phoenix canariensis (Canary Island Date Palm) have been found with this disease, but that is extremely rare.

Can Be Confused With: Petiole and rachis blight.  It can also be confused with Ganoderma.  However, Queen palms with Ganoderma usually will have a wilted look, while with Fusarium Wilt the fronds have a more rigid appearance.  

Preventative Measures: There is no cure or treatment for this fungus.  Therefore, the best solution to prevent this disease is to make sure either a new pruning tool is used on each palm, or the pruning tools are sterilized before pruning each palm.  The fungus will not infect a palm through dead material.  Therefore, only completely dead fronds should be removed when trimming susceptible palms.

Solution: Only hire a knowledgable professional to trim your palms.

Fatality: This disease is fatal.  The disease can translocate into the roots and soil, so it is not advisable to plant the same species back into a diseased palm’s location.

More Information: https://edis.ifas.ufl.edu/pdffiles/PP/PP27800.pdf

What Happens: Ganoderma zonatum is a soil borne fungus that deteriorates the vascular system in the lower trunk of the palm. 

Symptoms: Fronds often look wilted (especially on palms with softer fronds, such as Queen palms) and the palm lacks vigor.  The fronds die from the bottom up more rapidly than normal.  The spear leaf is the last to die.  Conks often develop on the lower trunk of the palm, but not always.  The palm is subject to collapse.

Susceptible Palms: As far as we know, all species of palms are susceptible.

Can Be Confused With: Fusarium Wilt and Lethal Bronzing Disease. With Fusarium Wilt there will be a one-sided decline of the fronds. With Lethal Bronzing Diseases, the spear leaf will die after 25% of the canopy die,. while with Ganoderma Butt Rot the spear leaf is the last to die.

Preventative Measures: There is no way to prevent this disease.

Solution: Once conks develop, they should be removed and sealed in a plastic bag and disposed of with normal household waste (not lawn waste).  The palm should be removed ASAP and the stump should be ground or removed. The conks are the fruiting body of the fungus, and the conks can produce millions of spores, which can spread by wind and water to other palms. Since this is a soil borne fungus, another palm (monocot) cannot be planted in this same location.  A tree (dicot) can be planted in this location since Ganoderma zonatum does not affect dicots.

Fatality: This is a fatal disease. 

More Information: https://edis.ifas.ufl.edu/pdffiles/PP/PP10000.pdf

What Happens: The leaflets of the palm develop unsightly dark bumps.  This is more of an aesthetic issue and rarely causes adverse harm to the palm.

Symptoms: Black fruiting bodies less than 1/16 of an inch develop on leaflets of the older fronds.  Eventually yellow spores are produced and light colored thread-like filaments emerge from the black raised spots.

Susceptible Palms: Most common in Phoenix canariensis (Canary Island Date Palms) and Phoenix dactylifera (Phoenix Date Palms).

Can Be Confused With: Scale

Preventative Measures: Graphiola requires moisture from irrigation, rain, dew or very high humidity.  Eliminating irrigation water from getting on the fronds will help.  To help increase air circulation, increase spacing between the palm’s canopy and other plants in the landscape.  Heavily infected fronds can be removed to help reduce the inoculum levels.  This should only be done to palms free from nutritional deficiencies.  Removing fronds from palms with nutritional deficiencies will adversely affect the palm and is much more harmful than the Grapholia is.

Solution: Plant a different species of palm or adjust to the appearance of the Grapholia, since this fungus will not likely adversely affect the palm.  Fungicides have limited success at controlling Grapholia because of the difficult regiment that must be followed regarding the timing of the applications.

Fatality: Cosmetic, doesn’t affect growth, and therefore, will not hurt your palms.

More Information: https://edis.ifas.ufl.edu/pdffiles/PP/PP14000.pdf

What Happens: Lethal Bronzing Disease (LBD), a phytoplasma, compromises the vascular system of the palm.

Symptoms:

• Fronds die rapidly from the bottom up 

• Necrotic inflorescence

• Premature fruit drop

• Spear leaf collapses and the palm dies

Susceptible Palms:

Can Be Confused With: Fusarium Wilt and Ganoderma, however, with those two diseases, the spear leaf is the last to die.

Preventative Measures: Almost 100% preventable with regular (every four months) injections with the antibiotic Oxytetracycline Hydrochloride (OTC). See our OTC injection page for more information.

Solution: If you have a susceptible palm, have it injected it with OTC every four months.

Fatality:  Once the palm shows symptoms of LBD, it is too late to save it.

More Information: https://edis.ifas.ufl.edu/pdffiles/PP/PP16300.pdf  

What Happens: A fungal pathogen kills the surface of the petiole or rachis of the palm.

Symptoms: Discolored lesions/streaks on the petiole and/or the rachis of the oldest fronds.

Susceptible Palms: Most commonly affects Phoenix roebelenii (Pygmy Date Palms). Petiole and Rachis Blight can also be found on Cocos capitata (Pindo Palms), Phoenix canariensis (Canary Island Date Palm/Pineapple Palm), Phoenix sylvestris (Wild Date Palm), Phoenix dacylifera (Phoenix Date Palm) and Washingtonia robusta (Mexican Fan Palm).

Pindo, Canaries, Sylvestric, Dac., Washingtonias.

Can Be Confused With: Fusarium Wilt

Preventative Measures: Reduce moisture (overhead irrigation etc.) on fronds.

Solution: Often the palm will outgrow the fungus.  If the problem persists, prune off some of the worse fronds to help reduce the the inoculum levels.  This should only be done to palms free from nutritional deficiencies.  

Fatality: Rarely, if ever, fatal.

More Information: https://edis.ifas.ufl.edu/pdffiles/PP/PP14500.pdf

What Happens: Thielavopsis paradoxa, a fungus, enters a palm through open wounds. Open wounds can be caused by overpruning, chainsaws, woodpeckers, and people climbing palms with spikes.

Symptoms: Oozing from trunk, decline of canopy, and/or sudden collapse of the upper portion of the trunk. (Sometimes there are no symptoms before the palm collapses).

Susceptible Palms: All palms are susceptible.

Can Be Confused With: If the canopy is declining, it can be confused with Ganoderma, Fusarium Wilt, or LBD.  However, upper trunk collapse rules out these other diseases.

Preventative Measures: Avoid giving open wounds to any living portion of the palm.  This includes pruning green fronds.

Solution: Reduce chances of infection by eliminating open wounds.

Fatality: This is a fatal disease.

More Information: https://edis.ifas.ufl.edu/pdffiles/PP/PP14300.pdf