Gardening: Ganoderma disease tough on 2 local palms

It's called Ganoderma Butt Rot and it is a widespread palm disease affecting trees all over Marco Island and the southeastern United States.

One of the earliest and most easily recognizable symptoms of this disease is the fungal conk on the lower portion of the trunk near the soil lane.

Photo by EILEEN WARD, Eagle staff

One of the earliest and most easily recognizable symptoms of this disease is the fungal conk on the lower portion of the trunk near the soil lane.

This disease has been found on about 40 or 50 species. Yet it is thought that all species are probably susceptible.

The two palms that are affected by this disease the most — on Marco Island — are the queen palm and the areca palm.

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

Symptoms begin as wilting and death of the oldest fronds, but gradually progress up through the canopy until the bud is dead.

One of the earliest and most easily recognizable symptoms of this disease is the fungal conk on the lower portion of the trunk near the soil line. These conks start out as small, white lumps and quickly mature into brown, woody brackets up to a foot across.

These conks can release millions of spores that are capable of infecting dead palm wood or healthy palms some distance from these conks. While wounds on palm trunks increase the likelihood of infection, they are not necessary for infection to occur.

Ganoderma can also 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 because this can transmit the disease to healthy palms.

Any new conks should be removed quickly and regularly to prevent the production of spores which could spread to neighborhood trees.

It is common for Ganoderma to infect clumping palms such as the areca. When mature canes of these palms are removed, the dead stump is quickly invaded by Ganoderma spores that then 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 disease in trees. 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 planting trees in areas where trees have previously succumbed to root disease, first remove old stumps and roots to reduce local fungus present. Then consider soil sterilization using chemicals or solar radiation.

Pruning tools also spread this disease and landscape maintenance personnel should be aware of this 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 who trim hundreds of trees a day by using a chainsaw.

The small crooks and crevices of a chainsaw make cleaning it thoroughly after each job virtually impossible.

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Eileen Ward and her husband, Peter, own and operate Greensward of Marco Inc., a lawn maintenance and landscaping company. Besides completing horticultural courses from the University of Florida, she has a commercial maintenance spray license and is a registered dealer in agricultural products in Florida. To reach Ward, call 394-1413.

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