Treating Cold-Damaged Palms
Cold weather slows the growth of palms, reduces activity of the roots, and often weakens the plant to the point where a disease can become active and kill the palm.
Often, the only above-ground portion of a cold-damaged palm that is still alive is the protected bud. In most cases, the death of the bud soon after a freeze is due to bacteria that is present at low levels of a healthy palm, but becomes a problem only after the freeze damage.
Possible Preventative Action
There may be value in applying a preventative spray of fungicidal copper before freezing temperatures are reached in order to reduce these bacterial populations to the lowest levels possible. This strategy, however, has not been tested under controlled conditions. It is also important that palms receive a balanced fertilization in late summer or early fall to ensure that foliar nutrient levels are near optimum as winter approaches.
Protecting the Damaged Palm While Waiting for Warm Weather
Remove the cold-damaged portion of the leaves. Leaves should not be completely removed if they are green, even if they are spotted from the cold. The green intact portions of the palm are important to ensure adequate photosynthesis during the recovery stage.
Immediately after pruning, spray the palms with a fungicide containing cooper at the recommended rate. The use of fungicide is recommended only for palms not bearing edible fruit. Include a spreader sticker. Then, repeat the cooper spray 10 days after the first treatment or use another broad spectrum fungicide. Contact you County Extension Agent for current fungicide recommendations. In all cases, the sprays must cover the damaged tissue and healthy bud thoroughly.
Warmer weather promotes rapid growth; this helps the palms recover. A monthly application of soluble nutrients should be applied to the leaves of ¼ to ½ teaspoon per gallon S.T.E.M.® (Peter's Soluble Trace Element Mix) Spreader sticker.
If leaves emerging during the spring and summer months appear deformed, partially browned or otherwise abnormal, this may be indicative of embryonic leaves within the bud that were severely damaged during the winter. In most cases, the palm will grow out of this later in the season. Freeze damage to conducting tissue in the trunk may limit the ability of the palm to supply water to the canopy of leaves. Palms do not have the ability to regenerate conducting tissue in the trunk. Sudden collapse of some (or even all) of the leaves in the crown during the first of spring and the high temperatures of summer after a winter freeze may indicate that this type of trunk damage has occurred. Unfortunately, there is nothing that can be done to remedy this, and loss of the palm is inevitable.
The above steps will help you reduce loss from cold-damage and speed recovery. Nutrient sprays should continue into the summer if the plants are young or newly established in the landscape. Older palms will benefit from a soil application of a granular palm fertilizer in the spring, but it must be repeated every three to four months.
Compiled by Jalil (Jay) Vedaee from Treating Cold-Damaged Palms by Alan W. Meerow.