Palm Tree Cold Damage and what to look for

What to do this week
By Mark Govan, Host “Florida Gardening” on 970WFLA

ABC Pest Control Inc. FloridaPalm Tree Cold Damage and what to look for – By Mark Govan, Host “Florida Gardening” on 970WFLA

Florida enjoys a wide selection of palms, which many of us do not know are grown all over the country. These palms are shipped to our local nursery and garden centers drawing homeowners to them in droves. Questions on how well these palms will perform in Central Florida are rarely asked by the purchasing homeowner. We just assume that since our neighbor has one of these palms in his or her yard then, of course, it will grow in mine. Nothing may be further from the truth, and many of us are beginning to learn this little secret. In this week’s article, I will try to explain some of the problems you may witness on your palms when the cold weather descends on Central Florida. I will also cover some of the unusual symptoms you may still be seeing on your trees from last season’s cold weather. Let’s get started.

Fortunately, many of us will not have to worry about the palms we are currently growing in our landscapes. Queen palms, Washingtonia, Sabal, Paurotis, and most of the Phoenix variety palms are pretty well established here and should be fine barring another 1982 freeze. Unfortunately, those of you that have been purchasing some of the more exotic palms like the Foxtails, Cuban Royal, Coconut, Bottle, Fishtail, Triangle, Christmas, and Veitchii may be setting yourself up for problems due to a cold-weather front in your future. All of these palms and others not listed here could be susceptible to damage by the cold, and you need to be aware of this.There are some homes with micro-climates where a few of us can grow these tropical palms without the worry of damage but most of us purchasing these plants are not considering this. Growing these palms on the south side of a body of water or next to a brick home can offer some protection from the cold, but do not count on it. Palms planted in groups or close to the drip line of larger trees can fare much better during a cold-weather event than those planted alone or in the open. Tropical palms planted in the open will be susceptible to the cold.

There are some homes with micro-climates where a few of us can grow these tropical palms without the worry of damage but most of us purchasing these plants are not considering this. Growing these palms on the south side of a body of water or next to a brick home can offer some protection from the cold, but do not count on it. Palms planted in groups or close to the drip line of larger trees can fare much better during a cold-weather event than those planted alone or in the open. Tropical palms planted in the open will be susceptible to the cold.There are three types of injuries cold-weather can have on our palms; chilling, frost, and freeze damage. These injuries can be more or less pronounced depending on additional factors such as wind speed, duration of the cold, and finally the location of the palm. Since many of the palms, we have been planting in Central Florida have not been tested for several years by a winter event, many of us have become complaisant when selecting plant material to use in the landscape. If we get another winter event such as the one we experienced in 1982, then we will all get a

There are three types of injuries cold-weather can have on our palms; chilling, frost, and freeze damage. These injuries can be more or less pronounced depending on additional factors such as wind speed, duration of the cold, and finally the location of the palm. Since many of the palms, we have been planting in Central Florida have not been tested for several years by a winter event, many of us have become complaisant when selecting plant material to use in the landscape. If we get another winter event such as the one we experienced in 1982, then we will all get a wake-up call on the types of plants we should be using in Central Florida. Unfortunately, as time goes by, we forget about these events. Knowing the signs of cold damage can be helpful if we are to save a palm from an untimely death.

Chilling injury to palms can occur overnight or over a long period of time. Because most exotic palms can be injured by temperatures far above freezing, most people do not equate temperatures in the mid-forties as damaging. Tropical palms can be damaged whenever temperatures fall below forty-five degrees, especially when temperatures drop rapidly. When temperatures average in the seventies for several weeks at a time and suddenly drop below forty-five degrees, chilling injury can occur very fast. Damage from even a single night where temperatures drop quickly can kill the outermost fronds and damage the northern exposure of the trunk overnight. However, palms which receive gradually falling temperatures’ night after night or those trees which are protected by the foliage of other trees or by location, may not show any damage until temperatures drop into the low thirties.

Symptoms you may see on your palms from chilling injury will occur on the older fronds and be closest to the leaf tips. Some leaves may show a curling along the leaf edge, and newer fronds could show a reddening color. Fruit may also show damage or be aborted depending on the intensity of the cold weather. New fronds produced even months following the chilling effect could show symptoms of deficiencies not related to an element shortage but rather from the slowed rate of nutrient absorption during the cold spell. This could be very noticeable in palms that are subjected to prolonged cold during times of routine growth. Some palms may produce multiple new spear leafs, which do not open. This symptom would normally indicate a boron deficiency but during prolonged cold spells, you may not be able to tell difference. These problems will ordinarily disappear over time once the trees are returned to normal temperatures.

Frost damage is much more destructive to tropical palms. Although frost is sometimes spotty, it can damage much more fronds on the tree, including the growing bud. If the bud is injured and dies, then the tree will follow. On clear windless nights, frost can completely cover an entire palm, including their trunks. Royal palms, Areca palms, and Christmas palms are especially susceptible to heavy frost damage. I have seen the green crown shafts of large palms like the Cuban Royal severely damaged from cold weather. Even sizeable Areca palms have been completely defoliated by frost. Fortunately, Arecas seem to recover quickly, but they need to be heavily pruned. Please note that no pruning should be done on any cold-damaged palm for at least four to six weeks after the threat of additional freezes to have passed. Old and even dead fronds may help protect the plant from any future freezes and should be left on the plant.

The last and the most devastating problem our tropical palms have to bear is a hard freeze. A hard freeze is when temperatures reach below thirty-two degrees for any substantial period of time. During this time the first parts of the plant to show damages are the flowers and fruit. Mature fronds will begin wilting and withering. The petiole or lower portion of the frond and the bud or apical meristem (this is where all new fronds develop) are the hardiest parts of the palm and are usually the last to die. In a severe freeze, most of the foliage will be lost but please do not remove them. Longitudinal cracks may also form or be observed on the trunk and the crown shaft of the plant. Some of these cracks have measured more than a foot in length. Bleeding from these cracks can be a precursor to trunk decay. Sometimes these cracks may take several months to one year after the freeze to form. Palms which were maintained and fertilized regularly with a high-quality palm tree fertilizer will have a much better chance of survival than those that did not.

New fronds which develop after the freeze may seem to develop normally at first but then tend to fall over and die due to the bud decaying in the tree. Spraying or drenching the bud on the tree with a copper fungicide every seven days following a freeze may help control secondary fungi and bacteria from infecting the bud. Unfortunately, there is no control for the trunks of trees, which have been visibly damaged by the cold. Those trees with soft or sunken pockets, cracked, bleeding or wet areas, may need to be removed before they become a hazard. In many cases, you will notice a strong odor coming from the tree prior to total death of the tree. It is not uncommon for the entire crown of the palm to fall over several months after a freeze.

Selecting the right palm for your home needs to involve a little research of that palms natural growing environment. Purchasing a palm that only grows in South Florida can lead to significant problems when planted in Central Florida. All palms need specific nutritional feedings to keep them healthy and vigorous. Pruning should only be performed when the fronds are completely dead or to remove pods. If your palm has been injured in a freeze, then call out an arborist to look it over and make the recommended treatments to try to save the tree. There are no guarantees with a freeze. Enjoy your landscape and remember, without plants we would not be here.

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