Initial Freeze Damage Mitigation Protocol
The information contained below is a composition of the experience, opinions & observations of George Nottingham, the founder and president of Groundworks of Palm Beach County Inc. Readers are encouraged to collect information from as many sources as possible and to use their own experience and observations when making decisions in the field. The protocol set forth at the bottom of these pages is that which is employed by Groundworks under the circumstances described however, neither George Nottingham nor Groundworks make nor mean to imply that there is any guarantee or warranty of fitness of purpose or effectiveness where this information is applied in the field. The sole assurance offered is our statement that this information is presented with no motive other than our hope that it may aid professionals and others seeking solutions to the problems described.
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Freeze damage in tropical and subtropical palms during advective and/or radiational freeze events.
Initial Damage Mitigation Protocol (IDMP)
“Freeze” Damage Tropical and Sub-tropical species of palms may suffer serious damage during radiational and advective freeze events. It is unlikely that Subtropical palms will suffer damage from chill events and the degree of damage suffered during advective and radiational events will be governed by factors associated to the species’ themselves, the nutritional state of the palms (at the time of the event) and by the micro cultural conditions in which the palms are growing during the event. During early February of 2014 an extreme advective freeze event occurred in the Southern United States impacting palms growing in Southern landscapes.
Generally speaking As a rule, freeze damage in palms is most readily demonstrated in older and secondary fronds, it is somewhat less exasperated in the spear leafs and it will be least expressed in the meristem. Damage to older and secondary fronds is functionally problematic because of the loss of frond surface area in which plant carbohydrates would otherwise be produced. This loss of live frond surface area reduces the amount(s) of plant carbohydrates that are available to support plant processes and is a key factor associated to the instigation of an aggregating state of general weakness. This state of weakness is another form of associative damage and its enabling establishes circumstances wherein opportunistic disease and bacterial colonies will become more problematic.
Damage to, or the outright loss of the spear leafs is serious because the spears are the emerging sets of fronds that would otherwise mature and become sources of plant carbohydrates. If during an extreme advective or radiational event the spears are entirely destroyed, it is highly likely that the mature fronds have also been destroyed leaving the palm with little or no means by which it can create new plant carbohydrates.
Serious damage to, or the death of, the meristem is the most serious possible result of an advective or radiational event. Even where the spear leafs have been totally destroyed, many species of palms will regenerate new spear leafs from the meristem thus the loss of the spears does not necessarily indicate the destruction of the meristem. Only the complete destruction of the meristem will leave the palm completely dead. Where meristem damage occurs, it is possible that the damage may not be complete and that portions of it may remain alive post-event. In these cases and where sufficient moisture & carbohydrates are available AND where bacterial and/or disease issues do not interfere, the meristem will produce new but deformed spear leafs (fronds) which will emerge. Whether or not these will fully mature and whether or not the meristem will heal and later produce normal fronds will be determined by a variety of micro-cultural factors, some of which can be positively influenced via treatment regimens.
Generally speaking, this is the reason that some professionals will recommend leaving all damaged fronds on the palm until such time as new fronds have emerged. Practically speaking, the rachis of those damaged fronds contains carbohydrates that had been produced in the frond tissue prior to the event. Once the leaflets are fully desiccated (Browned) by the temperatures, they are no longer capable of producing carbohydrates but carbs which already exist will continue to be drawn into the trunk and are beneficial to the palm. The availability of these carbohydrates when so much of the tissue has been rendered dysfunctional is important and may be considered one of the only immediate sources available to the palm until such time as new tissue has emerged. The rachis’s of the desiccated fronds will remain moist and vital (but decreasingly so as they dry down) for a period of time after the event and the palm will continue to draw sustenance from them.
As the damage to frond tissue & rachis exasperates post-event, this tissue will be drying down and conduction from stores contained within will slowly but inexorably be inhibited and then eliminated. In my experience, after severe events the rachis tissue of severely damaged fronds has reached a point of substantial dry down to the trunk within 14-21 days (post-event) and what you are then left with as a primary consideration is “Why are the palms on site to begin with”? If the primary value to the site is aesthetic in nature (most people own palms for the aesthetics they bring to the site) then leaving the browned tissue on the palms beyond 21 days is detrimental to value. While it may be true that removing them at that point may eliminate what has by then become a small and quickly diminishing source of carbohydrates, the majority of stored carbs have already been drawn, the frond is incapable of making more and the palm has become substantially unsightly. In addition (and to my mind of equal importance) is the fact that the dead tissue is becoming a harboring point and breeding ground for bacteria & disease. As such, I recommend leaving all fronds on damaged palms for at least 14/21 days and then, where aesthetic considerations motivate action, removing all completely brown frond tissue but leaving any tissue that is still green.
“Responsive” and “Associative” damage This event resulted in serious damage to many varieties of tropical and subtropical palms on your sites and that damage may be classified in two distinct categories. I term the first category of damage as being “Responsive” damage. Responsive damage is that damage which occurs in direct response to the low temperatures and to the duration(s) during which the palms were exposed to those temperatures. Responsive damage was done to the canopies, meristems, trunks and to the near surface portions of the root systems. Responsive damage to the canopies became immediately evident and has been seen to “apparently” exasperate during the past weeks. “Apparently’ because the entirety of inflicted responsive damage was done during the event(s) and it is the visually apparent symptoms of that damage that are exasperating with the passage of time. While the canopy issues are obvious, responsive damage to root, trunk and meristem tissue is not so readily apparent and the impacts will take time to reveal themselves.
I term the second form of damage to be “Associative”. Associative damage occurs during the weeks and months after the event concludes. Associative damage takes different forms including disease proliferation, bacterial colonization, nutritional deficiency (and the state of general weakness that the developing deficiency instigates) and the impacts each of these will have on the palm. Associative damage issues are the primary instigating factors which cause the loss of the palm in scenarios where palms were damaged but not destroyed outright during extreme events. Associative damage most commonly develops when untreated palms are exposed to warmer temperatures. Warmer weather occurring just after extreme events tends to encourage the formation & growth of bacterial colonies in damaged tissue and it encourages the establishment & proliferation of opportunistic disease causing pathogens. Associative damage is also represented by an aggregating state of general weakness that ensues in response to the elimination of carbohydrate producing frond tissue.
Responsive Damage During the end of the first week in February I personally inspected sites in the coastal region of the Florida Pan Handle. On sites across the region, substantial responsive damage occurred leaving entire canopies of tropical and sub-tropical species nearly or fully desiccated. In the case of the tropical Phoenix Robellini, the palms uniformly suffered an extreme degree of responsive damage. This damage initially demonstrates as the complete desiccation of the entire canopy & spear leaf(s) and I believe it likely that the meristems of a great many of these were destroyed. While it is possible that some of these tropicals will survive and initiate new growth from the meristem, I anticipate that any growth may be deformed, the volume of tissue produced will be very light and the palm’s innate capacity to nurture that emerging tissue will be disenfranchised to the extent that it may allow the initiation to fail relatively soon after emergence. I further believe that the trunks of this species suffered severe responsive damage and that trunk tissue necrosis & rot will soon ensue.
In the case(s) of Sub-tropical species, the responsive damage varied substantially from species to species. Impacted Chamaerops sp. (European/Mediterranean fan) and Trachycarpus sp. (Windmill) palms suffered little or no apparent responsive damage. Phoenix Dactylifera Medjool palms demonstrated the greatest degree of cold hardiness of the all of the specimen palms inspected. The Medjool’s demonstrated with responsive damage ranging from only (approximately) 15 to 35% desiccation in the lower & mid-tier fronds and just 5 to 25% desiccation in the spear leafs. Impacted Syagrus sp. (Queen), Washingtonia sp. (Mexican fans and Filifera crosses,) Phoenix Canariensis and Phoenix Sylvestris demonstrated with responsive damage ranging from approximately 65 to 95% desiccation in the lower & mid-tier fronds and 35 to 90% tissue desiccation in spear leafs.
In addition to visually apparent responsive damage to canopies, a degree of damage to trunk tissue may have occurred in these species. In portions of trunk tissue suffering responsive damage, tissue necrosis and rot may become apparent during the weeks & months following the event. This damage will demonstrate as soft areas in the petiole along the trunk. These soft areas are initially a product of event instigated desiccation which is followed by bacterial colonization resulting in severe necrosis in the adjacent petiole and trunk tissue. These areas, if left untreated, will become points at which disease establishment is encouraged and they may also represent initialization locations from which a loss of structural integrity may exasperate to the point of catastrophic structural failure. With such an eventuality in mind, the initial damage mitigation protocol will take steps to guard against the establishment of Thielaviopsis paradoxa trunk rot.
Early on in the process, the existence and/or severity of responsive trunk damage cannot be accurately determined however, given the severity of the advective event, it is sensible to plan for responsive damage to trunks and to include a wood rotting disease prevention measure when formulating the initial damage mitigation protocol. During the coming 6 months I suggest that professionals implement an inspection schedule and inspect the trunks of impacted palms carefully on a regular basis. If soft spots on the trunks are discovered, contractors may contact Groundworks to discuss an unconventional secondary protocol that we have successfully employed in the past to address these issues.
The severity and duration of the event may have also caused responsive damage to the near surface portion of the live capillary root systems of impacted palms. This damage will demonstrate as a blackening and drying back of impacted root tips and can result in various degrees of capillary root system dysfunctionality. It is highly unlikely that debilitating primary root system damage could have occurred during this event but damaged capillaries at or near surface may become necrotic and so become harboring points for soil borne pathogens. This possibility has been addressed when planning the initial damage mitigation protocol and there are other steps you can be taken in a secondary protocol to instigate the regeneration of fully functional capillary systems should contractors feel that functionality has been compromised. In this event, please contact Groundworks to discuss secondary protocols.
Associative Damage As of the date of this opinion, the degree to which the Subtropical species will suffer from associative damage is still to be determined but associative damage may be partially or fully mitigated by the treatment efforts implemented by professionals. Effective treatments to mitigate the risk & impacts of Responsive & Associative damage will be contact, systemic and procedural in nature. In my experience, these efforts will be most effective when initiated no less than 14 days after the conclusion of the event.
The damage mitigation protocols set forth below are designed to limit the formation of bacterial colonies, act to prevent the establishment of disease in the meristem, trunks & roots and, to the extent it is possible, to encourage the production of carbohydrates in whatever live tissue still exists.
Recommendations
Initial Damage Mitigation Protocol (IDMP)
*** Prior to trimming, contractors should insist that their personnel mist and wipe their trimming tools/blades using isopropyl alcohol or chlorine bleach to insure that no live bacteria or pathogens are transmitted from the blade(s) to the subject palm(s). This needs to be done before starting at each site and then repeated after each palm is completed. Disease transmission on trimming tools is a serious problem that can be avoided via attention to this simple practice.
- No action whatsoever during initial 14 days after conclusion of the event. During this time frame, do not trim the palms nor take any other actions. Perform an irrigation check to insure your ability to properly irrigate the palms during treatment and thereafter.
- Before commencing drench work, on sites where the soil/surface conditions may encourage run off of subsequent soil/root drenches, use a steel bar and punch a group of holes approximately 6” deep around the base of each trunk. These should be made approximately from 8” out to approximately 24” out from the trunk all the way around the palm. There is no specific pattern that should be employed; you are simply creating a group of small reservoirs over the root system. These will act to trap and concentrate soil/root drenches.
- After at least 14 days have passed, trim away all fully desiccated (browned) frond tissue and frond tips (older fronds and spear leafs) but do not cut away any green tissue. Also cut away any inflorescence (Male or female reproductive parts). These are removed regardless of their condition. In the current scenario, we do not want the palms focusing (for want of a better term) on proliferation, we want them focusing on tissue regeneration. With the reproductive parts removed, the palms will direct carbohydrates more decisively to new tissue regeneration.
Once trimming is completed, drench the remaining canopy utilizing IDMP mix #1. Insure that all canopy surfaces are wetted and that the mix runs down into the area of the spear leafs/meristem. Once complete, perform a soil/root drench utilizing IDMP mix #2 and then drench the entire trunk of each palm utilizing IDMP mix #3. The run off from the trunk drench will act as a further soil drench.
- 21 days after the initial applications (35 + days post event), repeat step 3 utilizing the same mixes and initiate fertilization utilizing IDMP Fertilization Protocol A.
- 35 days after second application (70 + days post event), repeat canopy spray utilizing IDMP mix #1 and trunk spray utilizing IDMP mix #3. Once complete, fertilize using IDMP Fertilization Protocol B.
Thereafter return to normally scheduled Performance Assurance (maintenance) schedule.
Throughout the treatment protocols and then as a standard of your Performance Assurance (maintenance) work, maintain a wet to moist, wet to moist state in the upper 24” of the soil layer.
Initial Damage Mitigation Protocol (IDMP) chemical Recommendations
Apply all chemicals in accordance with the instructions set forth on the labels. Groundworks cannot tell you what rates to use; the label is the governing authority and its instructions must be closely followed. The list below reflects the rates that we would seek to use if it was Groundworks doing this work but that is for informational purposes only; contractors must read the labels and follow the label instructions. All mixes of our mixes are set up using 50 gallons of water.
IDMP Mix #1
8 Ounces “Junction” Fungicide
2 Cups 0-0-22 Liquid Potassium
2 Cup Phlex mag or other nutritional solution containing at least 2.5% Magnesium
1 Cup Macron 16-32-16
IDMP Mix # 2
½ ounce Mefenoxam (Subdue or equivalent)
6 ounces Superthrive (Superthrive.com)
2 Cups 0-0-22 Liquid Potassium
2 Cups Phlex mag or other nutritional solution containing at least 2.5% Magnesium
IDMP Mix #3
12 ounces T-Storm OR Cleary’s 3336 Fungicide
IDMP Fertilization Protocol A.
This initial fertilization will be light and will be more readily available than that which you will use during your standard Performance Assurance/Maintenance work. The amount of fertilizer to be used on each palm is highly subjective; in my opinion, a good rule of thumb for this initial IDMP application is approximately 2 ounces per inch of trunk caliper. You do not need to get that exactly right; you just need to be relatively close.
Utilizing a 12-4-12 + Minors in a quantity that approximates 2 ounces per caliper inch of trunk, to a maximum of 3 pounds per palm, spread the fertilizer over the majority of the root zone. Spread/distribute the fertilizer to within 6 inches of the trunk and out to approximately 3’ from the trunk (where possible). This light feeding will be encountered by the majority of the near surface root system.
IDMP Fertilization Protocol B
Utilize a blend that is comprised of 60% 12-4-12 and 40% Slow release Potassium/Magnesium mix.
This secondary fertilization will be heavier and is also the ratio I recommend for Performance Assurance (maintenance) work contractors perform on a quarterly basis. The amount of fertilizer to be used on each palm is again considered to highly subjective but I recommend a rate equal to approximately 4 ounces per inch of trunk caliper to a maximum of 8 pounds of fertilizer per palm, per application. Here again, contractors will spread/distribute the fertilizer blend to within 6” of the trunk and out to 3’ from the trunk all the way around the base.
*Please bear in mind that the spray mixes and soil drenches applied contain nutritional elements as well.
Contractors requiring site/material inspections or consultations may contract with Groundworks to have a specialist engage the process of creating site specific solutions to your issues. Please contact our offices at (800) 753 5127 or [email protected].
We wish you the best of luck on site and are available to further assist you as your needs may require.
Warm regards and blessings to all for the Holidays;
George P. Nottingham
President
Groundworks of Palm Beach County Inc.