Most people know that good hygiene stops the spread of disease between humans, but they forget that the same goes for trees.

Dr. Monica Elliott and Dr. Timothy Broschat from the University of Florida were in Bermuda, to look at the health of Bermuda's palms and to give a lecture with the Government Plant Protection Lab.

They co-authored 'A Compendium of Ornamental Palm Diseases and Disorders' along with J. Uchida and Gary Simone.

Dr. Elliott told The Royal Gazette she and Dr. Broschat had seen some puzzling problems with Bermuda's palms.

"We are not sure what is wrong with the coconut palms," said Dr. Elliott.

The good news is that they have seen no evidence of lethal yellowing, a disease that destroyed about three quarters of coconut palms in Key West, Florida, in the 1950s.

"We are not sure why the palms here have kind of a wilted appearance on the leaves," said Dr. Elliott.

"We are seeing a little bit of the Fusarium wilt on the Canary Island date palm. That is about the only serious disease we have encountered."

Fusarium wilt is caused by a fungus Fusarium oxysporum f. sp. canariensis.

"So far, it is presumed Fusarium," Dr. Elliott said.

"If you look at an entire palm leaf with the disease, you will notice that one half of the leaf is dead while the other half is still green. And on the half that is dead you will see a brown stripe going from the base of the leaf all the way up to the tip."

Although there is another palm disease with similar symptoms, the fact that the palms she is seeing are dying, indicated the culprit was Fusarium.

The primary method of transmission is the use of contaminated pruning tools.

"If you cut into one diseased and then start trimming on another that started out as a healthy palm, you are likely to spread it," said Dr. Elliott.

"That is why we recommend people sterilise their pruning tools."

The disease can also be spread by planting contaminated seeds. "If someone takes seed off of an infected palm, and starts up a seedling, it can be in the seedling," said Dr. Elliott.

Terri Lyn Thompson, Senior Government Plant Protection Officer, said it is prohibited to bring palm seeds onto the Island.

"We have people bragging to us about bringing in palm seeds," said Miss Thompson.

"If people are going away on vacation, they should leave the seeds there."

Dr. Elliott said they didn't yet know the extent of the Fusarium wilt problem in Bermuda, but it highlighted why vigilance was needed.

"We haven't done a survey," she said.

"We just know that it is here, and the fact that it is here would be enough of a concern that one should start cleaning pruning tools, especially when it comes to the Canary Island date palm."

Dr. Elliott said cleaning pruning tools was not difficult. Gardeners and landscapers can use a Clorox or Pinesol solution on their tools.

"There are a lot of different solutions you can use," Dr. Elliott said. "It is just a matter of getting in the habit of doing it."

Miss Thompson said the palm tree population in Bermuda wouldn't necessarily be wiped out by the disease, but it could be badly affected.

"If there is a disease like Fusarium on a property and if the landscapers are not disinfecting their tools, it will be transmitted from one palm to another," she said.

"I sigh with relief that Dr. Elliott does not see any symptoms indicating lethal yellowing here."

Aside from the Canary Island date palm, the visiting palm experts had also seen problems with the coconut palms in Bermuda.

"They do not look healthy," said Dr. Elliott. "But I think it is probably more of an environmental issue. So far, every place we have been, they all look the same.

"If the cause was disease you would have pockets. You would see all the palms on one side of the Island dying and on another side nothing.

"Here, we are seeing it across everything. So that is indicating there is some large environmental issue. The cause is really difficult to determine."

She said it could be weather patterns, climate change or some other stress on the tree.

Dr. Elliott said that in Florida, they have much more severe problems including lethal yellowing, and four or five other lethal diseases affecting palm trees.

Dr. Broschat's speciality is nutrient deficiencies in palms. Unlike other plants, palms can be killed by a nutrient deficiency.

He said: "There is no research to suggest that giving palms vitamins makes them resistant to disease.

"Most palm trees are suffering from varying degrees of nutrient deficiencies.

"Even in many cases, the lack of nutrients do not necessarily make it more susceptible to disease. In a few cases, yes, but mostly no. So they are kind of independent."

The good news is that most of the diseases that the palm experts see on palms are very specific. They only occur on palms.

"We don't worry about it being transferred between plants," said Dr. Elliott.

In fact, the Fusarium wilt is specific to the Canary Island date palm.

Lethal yellowing is also very specific and only occurs on palms."

While in Bermuda on this trip, Dr. Broschat saw what he termed the worst nitrogen deficiency he had ever seen in Devonshire. He took a photograph.

"We are seeing classic potassium deficiency and on top of that you see the leaf spot," said Dr. Elliott.

"People focus on the disease and not on the nutritional deficiency, when it needs to be done the other way."

Dr. Broschat said it is important not to trim the brown parts off of palm trees, because often the tree will be taking nutrients from the brown areas, particularly potassium.

"If you trim it, the brown will just move up the tree," said Dr. Broschat.

"Nutritional diseases are best prevented by proper fertilisation.

"To correct a deficiency may take years of proper fertilisation. It is a very long, slow process. Once you get the palm to that state it is fairly easy to maintain them with proper fertilisers.

"But incorrect fertilisation can create worse problems than if you don't fertilise at all. So it is important to use the right fertiliser."

Dr. Broschat admitted that he didn't have many palms at home in his backyard.

"We have as few at home as possible," he said.

"I see the problems. They are so high maintenance to make them look good, I prefer flowering trees myself."