Gardening: Preventive care is only solution to deadly palm disease

Ganoderma butt rot is a disease affecting palm trees all over Marco Island and the southeastern United States.

The disease has been found on about 40 or 50 species, but some experts think all species are probably susceptible.

The two most affected palms I see on Marco Island are the queen palm and the areca palm.

However, I have seen it on coconuts, sable palms and even oak trees. Ganoderma mainly affects mature palms.

Early symptoms are the wilting and death of the oldest fronds, but the disease gradually progresses up through the canopy until the bud is dead.

Among the earliest and most easily recognizable symptoms are fungal conks on the lower portion of the trunk near the soil line.

Conks start as small white lumps and quickly mature into brown woody brackets up to a foot wide. They can release millions of spores that are capable of infecting dead palm wood or healthy palms some distance away. While wounds on palm trunks increase the likelihood of infection, they are not necessary for infection to occur.

Ganoderma also can be spread through the soil, living on dead palm roots and wood.

It is important to remove infected trees from the landscape as soon as possible. Also, be careful to dig out the remaining stump after the tree is removed.

Infected palms should never be chipped and used for mulch.

This can transmit the disease to healthy palms. Any new conks should be removed quickly and regularly to prevent the production of spores that could spread to neighborhood trees.

Ganoderma commonly infects clumping palms like the areca. When mature canes of these palms are removed, the dead stump is quickly invaded by ganoderma spores that spread to healthy living canes until the entire palm is affected and killed.

Prevention is the only control for root diseases. There are no effective treatments for curing established root diseases.

Ganoderma butt rot starts as small white lumps and quickly matures into brown woody brackets up to a foot wide.

Photo by EILEEN WARD, Marco Eagle

Ganoderma butt rot starts as small white lumps and quickly matures into brown woody brackets up to a foot wide.

Promoting overall tree vigor by properly fertilizing and watering is a good start. Avoid damaging roots by digging too close to palms or wounding lower trunks. When you plant trees in areas where trees have previously succumbed to root disease, first remove old stumps and roots to reduce fungus. Then consider soil sterilization using chemicals or solar radiation.

Pruning tools also spread this disease. Landscape-maintenance personnel should be aware of the disease and its symptoms.

Palms showing decline should be pruned last in the landscape to avoid spreading the disease to healthy trees.

Pruning tools should be disinfected in a 1-to-4 dilution of bleach and water for a couple of minutes before trimming any healthy trees.

Unfortunately, this is not an option for professional tree- trimming companies that trim hundreds of trees a day with a chain saw. The small crooks and crevices of a chain saw make cleaning it thoroughly after each job virtually impossible.

One possible solution to this problem is to educate local tree trimmers about the disease.

Perhaps a separate, contaminated chain saw could be used on declining or diseased trees.

The next time you have your palms cleaned, give this column to your tree-cleaning company.

While this alone will not stop the disease, education is a step in the right direction.

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