Florida has beautiful palms. Until prune-happy tree trimmers get their clippers on them, that is.
Just recently I was admiring the Canary Island date palms around a local business – healthy, properly pruned trees with full canopies of nice dark green fronds. When I returned a week later they had been over-pruned into feather-dusters.
As I drive around the county I see over-pruning happening in too many places and it is disheartening. I know I shouldn’t take this personally, but it is rather maddening that after all the articles I have written and all the classes I have taught, our palms are still being “hurricane cut.”
Besides leaving ugly palms in their wake, a hurricane cut has many other negative consequences. For one, the fronds provide a much-needed wall of protection around the palm’s bud. Exposing the bud by removing too many fronds can allow more damage to occur during a storm, potentially causing injury or even death to the tree.
In addition, removing a lot of green fronds deprives palms of food and nutrients that allow them to grow and protect themselves from insects and disease. A weakened palm is more susceptible to damage and death from a storm. Over-pruning also may contribute to reduced winter hardiness.
Despite the long-time and on-going efforts of horticulturists and arborists around the state to educate tree owners, some – including commercial and governmental property owners – are still convinced that the practice saves money and protects houses and businesses. Convincing them that a hurricane cut actually hurts trees – and wallets – is quite a challenge.
If someone tries to talk you into this improper “maintenance,” please – for the sake of your tree – just say “no thanks.” For those of you who now realize that it is best to leave the fronds on palms, a big “thank you.”
Fertilizing is another palm issue that we are continually addressing. Sometimes bottom fronds start to turn yellow and brown and people assume those leaves are soon to die and can be removed. This is usually not the case. When a frond is ready to die it will go from green to yellow and then to brown in a very short time span, about three days. Fronds that remain discolored for longer than a few days indicate a nutritional deficiency. One of the leading causes of palm death is poor nutrition.
Palms in Florida can have many nutritional deficiencies that show up in the fronds. When the lower, older fronds are not evenly green it is usually because they have a macronutrient deficiency, frequently potassium and magnesium. Potassium deficiency can manifest as yellow spots or as broad yellowing with the tips of the fronds turning brown. Magnesium deficiency will cause yellowing along the edges with a wedge shaped green down the center of the frond. The older the frond, the more obvious the symptoms will be. Palms also can have more than one deficiency at a time and symptoms can overlap.
Micronutrient deficiencies are seen in the new fronds. Two of these deficiencies – manganese and boron – can produce bizarre growth. Manganese deficiency can cause the new growth to look frizzled or have dead streaks in the leaflets (individual parts of the frond). Boron deficiency can cause new spears not to open, corrugated-looking fronds, puckering, leaf hooks, crinkling, twisting and even cause the whole head to start growing sideways. Iron deficiency can cause general yellowing of the leaflets with dark green spots and leaflet tip browning.
Palms with any type of nutrient deficiency should only have the totally brown, dead fronds removed. Getting them back to health is all about using the proper palm fertilizer. It’s not the numbers on the bag but the materials used to make the fertilizer that really make the difference. The numbers should be 8-2-12+4Mg plus micronutrients, but, more importantly, make sure the N, K and Mg are 100 percent controlled release and that all the micronutrients are in the sulfate form. Iron is the one exception as you also can use cheated iron. All the other micronutrients must be in the sulfate form. During the Pinellas County summer ban on nitrogen and phosphorus use a 0-0-16+6Mg.
If you can’t use the correct fertilizer, you are better off not fertilizing at all!
Fertilizers should be evenly distributed under the palm canopy (no concentrated lines). If the palms are mixed in with grass or other plants, use only palm fertilizer within 50 feet of the palm.
For most yards that would mean using only palm fertilizer, which works for the grass as well.
If your palm is exhibiting problems, it can take up to two years to bring it back to good nutritional health.
You also can bring samples or pictures of your palms to the Pinellas County Extension Service at 12520 Ulmerton Road, Largo, next to the Florida Botanical Gardens.
The Help Desk is open from 8 a.m. to 5 p.m. Monday through Friday. To speak with a horticulturist, call 727-582-2110 on Mondays, Tuesdays or Thursdays from 9 a.m. to noon and 1 to 4 p.m. You also can visit us at www.pinellascountyextension.org.
Jane Morse, University of Florida Extension Agent, Pinellas County Extension provided this article.