Pests in Gardens and Landscapes
Palm Illnesses within the Panorama
On this Guideline:
A number of main, probably deadly ailments can assault panorama palms in California. The perfect technique for managing these ailments is an built-in strategy that mixes prevention, exclusion, sanitation, applicable species choice, and correct care. Choosing the fitting palm for the fitting spot, then planting and caring for it correctly, are essential to keep away from most ailments or assist palms get better from some ailments.
Preserve wholesome, vigorous palms by means of applicable choice and cultivation.
- Choose the fitting palm for the fitting place.
- Plant and transplant palms accurately.
- Observe applicable irrigation practices.
- Apply a specialised palm fertilizer—one excessive in nitrogen and potassium with half as a lot magnesium as potassium—following label charges and instructions.
- Maintain turfgrass, groundcovers, shrubs, and weeds no less than 2 ft away from the trunk, and keep mulch a number of inches deep over this space.
- Apply mulch.
- Reduce pruning and different cultivation practices that may wound palms.
- Keep away from utilizing chain saws and tree spikes, as a result of they will unfold inoculum and trigger wounds.
- Use straight-edge, guide saws, completely disinfect blades earlier than use on every palm, and prune out and appropriately discard of contaminated materials and palms.
- Do not recycle or chip contaminated materials to be used as mulch, as a result of it would comprise and unfold the pathogens.
Even if you happen to inherit a poorly tailored or managed palm, offering correct care can considerably scale back the possibilities for illness improvement and assist scale back illness severity. Prevention is often higher than treating a illness after it develops, and in some cases, it’s the solely possibility. Use fungicides solely as a final resort.
Desk 1 gives fast identification of the main palm ailments mentioned on this publication. Desk 2 lists frequent palms in California, their botanical names, and their resistance or susceptibility to those ailments.
Regardless of the identify, diamond scale will not be an insect pest. As a substitute the fungus Phaeochoropsis neowashingtoniae causes this frequent foliar illness, which derives its identify from its attribute black, diamond-shaped fruiting our bodies.
Hosts: Diamond scale assaults primarily the California fan palm in coastal areas and the intermediate and inside valleys of California topic to marine affect; it hardly ever happens in arid areas such because the Central Valley or the deserts of Southern California.
Diamond scale can happen on hybrids of the California fan palm with the Mexican fan palm, and the incidence and severity often are proportional to the quantity of California fan palm within the hybrid. Diamond scale has not been noticed on pure Mexican fan palm or every other palm species in California.
Signs and Biology: The palm usually has a a lot lowered cover of leaves. Older or decrease leaves prematurely yellow and die. Shut inspection reveals shiny black, diamond-shaped fruiting our bodies 1/Eight to 1/3-inch lengthy by 1/16 to 1/8-inch vast on leaf blades and petioles. Decrease, older leaves are most severely affected as a result of the longer the leaf stays uncovered, the better the variety of infections; nonetheless, even higher, new inexperienced leaves could have some black fruiting our bodies. Preliminary an infection websites are darkish, water-soaked spots the dimensions of a pinprick that finally flip black and enlarge.
Closely contaminated leaves have a black, sooty mud that rubs off simply whenever you brush towards or deal with them throughout removing, making the plant a nuisance to work with.
Illness severity typically is cyclical. The dry, heat seasons of summer time and fall favor progress of California fan palm moderately than diamond scale. Palms are inclined to develop shortly, producing leaves quicker than the pathogen can colonize them.
In distinction, the moist, cool seasons of winter and spring favor the pathogen over the host. Palms are inclined to develop extra slowly, and the illness advances greater into the cover, leading to a sparse cover of leaves.
Due to their extra vigorous progress price, younger palms are inclined to have much less illness and a fuller cover of leaves than older, much less vigorously rising crops.
Though not significantly deadly by itself, diamond scale reduces vigor and stresses the palm, leaving it weak to different ailments resembling pink rot.
Administration: The most suitable choice in areas the place the illness happens is to switch the California fan palm with diamond scale-resistant species of comparable behavior, such because the Mexican blue palm, San Jose hesper palm, Guadalupe palm, Australian fountain palm, Chinese language fountain or fan palm, Chinese language windmill palm, and pure Mexican fan palm.
Maintain present California fan palms as vigorous as potential by irrigating repeatedly, particularly in the summertime and through winters with little rainfall. Fertilize repeatedly to encourage fast progress.
The fungal spores that trigger diamond scale are all over the place and may journey by wind and water; due to this fact, eradicating and disposing of contaminated leaves might be not a viable administration technique.
|Illness and pathogen||Frequent hosts||Signs|
|California fan palm and hybrids with the Mexican fan palm (Washingtonia × filibusta)||
Fusarium oxysporum f. sp. canariensis
|Canary Island date palm||
|Largely the date palms and fan palms||
|Almost all outside panorama and indoor palms, particularly queen palm and California fan palm||
Contaminated crops weaken and may die, particularly if the apical meristem is attacked
|Sudden Crown Drop
Thielaviopsis paradoxa (unconfirmed)
|Canary Island date palm, date palm||
The fungus Fusarium oxysporum f. sp. canariensis causes Fusarium wilt, a deadly vascular illness of Canary Island date palm. The fungus destroys the vascular tissue of the palm, resulting in decreased water uptake, wilt, and loss of life.
Host: Totally different types of Fusarium oxysporum exist, they usually usually are host-species-specific. The shape in California, and known as forma specialis canariensis, causes illness solely on Canary Island date palms within the panorama. Nonetheless, in a subject experiment forma specialis canariensis additionally attacked California fan palm and Senegal date palm. Take into account that forma specialis canariensis has solely been noticed attacking Canary Island date palms, not different kinds of palm, in a panorama setting. Different types of Fusarium oxysporum trigger wilts on different kinds of date palms and different palm species however in different elements of the world.
Signs and Biology: The palm has a a lot lowered cover of leaves. Signs often seem in older or decrease leaves within the cover first, then transfer towards the higher or latest leaves, though often mid-canopy leaves are affected first. Leaves flip yellow then brown however stay hanging on the palm.
Initially signs would possibly have an effect on the leaflets or pinnae on just one facet of the leaf. Pinnae on the opposite facet stay inexperienced, though they finally additionally will flip brown and die. This sample was as soon as considered diagnostic for Fusarium wilt, however different ailments resembling petiole and rachis blights and pink rot can also trigger one-sided loss of life of leaves. Pinnae loss of life usually happens first on the base then strikes progressively towards the leaf tip, though this sample typically is reversed.
In distinction to petiole and rachis blights (see later), which additionally produce one-sided leaf loss of life however solely on a couple of leaves, usually with Fusarium wilt many leaves within the cover are affected or useless. The amount of diseased or useless leaves or inexperienced, wholesome leaves within the cover might help to establish most instances of Fusarium wilt. Usually with Fusarium wilt a preponderance of leaves within the cover can be affected or useless. Equally, if the palm is steadily pruned to take away useless leaves and continually seems to have a a lot lowered cover of residing leaves, it seemingly has Fusarium wilt.
One other frequent symptom of Fusarium wilt is intensive, exterior, brown to black discoloration or streaking alongside the petiole and rachis. This streaking corresponds to inside discoloration of vascular tissue when seen in transverse part. Internally the tissue is reddish-brown and sometimes has a slight pinkish blush; though incompletely understood, this pinkish discoloration could be diagnostic for the illness.
Within the panorama, Fusarium wilt practically all the time spreads on pruning instruments, particularly chain saws. The pathogen enters minimize petioles and, in excessive instances, the minimize and uncovered vascular tissue of severely pruned or skinned trunks (trunks the place the persistent leaf bases have been skinned or peeled off). The pathogen can unfold not directly throughout pruning, as a result of contaminated sawdust can drift so far as 100 ft.
The pathogen can also unfold by getting into the palm by means of its roots. Canary Island date palms are inclined to type a dense, intensive community of above-ground roots known as pneumatophores, particularly below excessively damp or moist circumstances, and these might facilitate pathogen entry.
Fusarium wilt would possibly unfold if folks eliminate diseased palms or their seeds utilizing a municipal yard-waste program that recycles particles into mulch. The pathogen can survive within the soil for no less than 25 years.
Contaminated palms can die inside a couple of months after signs seem, or they will linger for a number of years. As a result of wilt ailments lower the flexibility of the host to take up water, palms with Fusarium wilt in cooler, extra humid environments resembling close to the coast, would possibly present lowered illness severity and survive for a few years. Contaminated palms in hotter, drier inside climates would possibly present extreme signs and die quickly.
As a result of Fusarium wilt stresses palms, the opportunistic and principally secondary illness pink rot is steadily current and may obscure or masks signs and hasten loss of life. In truth, pink rot would possibly kill a palm earlier than Fusarium wilt runs its course.
Administration: As a result of no remedy exists for Fusarium wilt and it’s practically 100 p.c deadly, prevention and exclusion are essential to illness administration. When first planting, get hold of palms from a dependable supply, and keep away from poorly drained soils and extreme irrigation that may improve the formation of above-ground roots.
Maintain the realm across the base of the trunk freed from crops, which might injury above-ground roots, and keep away from utilizing municipal yard waste as mulch on Canary Island date palms.
Don’t replant a Canary Island date palm in the identical website the place one died or was eliminated due to Fusarium wilt. The fungus surviving can infect a brand new, wholesome palm. As a substitute, use different species of palms together with Mexican blue palm, San Jose hesper palm, Guadalupe palm, pindo palm, queen palm, and Mexican fan palm.
If you would like the date palm “look,” take into account staminate (male) crops of the date palm (Phoenix dactylifera), that are extra strong than the pistillate (feminine) fruit-bearing crops and extra carefully imitate the bigger, strong behavior of Canary Island date palms.
Often pruned Canary Island date palms usually tend to undergo from Fusarium wilt than these in an unmaintained setting. In case you should prune, completely clear and disinfect all instruments previous to work on every palm by vigorously brushing them to take away sawdust and different particles. Disinfect the instruments for 10 minutes in a 1:Three pine-oil-to-water answer, 1:1 answer of family bleach, or warmth noticed blades for no less than 10 seconds per facet with a handheld butane torch. Clear and disinfect (as described above) all instruments used within the root zones of Canary Island date palms resembling shovels, spades, rakes, hoes, and weeders, as a result of they will unfold the illness.
Use guide pruning saws moderately than chain saws every time potential, as a result of chain saws are tough if not inconceivable to wash and disinfect adequately. When you’ve got extraordinarily beneficial palms, think about using a brand new noticed for every tree, which you both might discard after one use or dedicate for future use on that one palm solely. Keep away from pruning palms in windy climate to attenuate the unfold of sawdust.
As a result of a Canary Island date palm with Fusarium wilt finally will die, it’s prudent to take away it as quickly as potential. To keep away from spreading the pathogen, excavate the basis ball and use a crane to take away the palm with its crown of leaves, trunk, and root ball nonetheless connected, if potential. Maintain chopping, grinding, and digging to a minimal.
Use plastic or picket obstacles to comprise sawdust and different diseased plant elements throughout removing. After amassing and securely bagging all particles, put together eliminated palms for incineration or removing to a landfill; don’t use a waste recycling program. Eradicating the soil will seemingly not stop the unfold of Fusarium wilt as a result of only one small piece of contaminated root is all that’s essential to infect a newly planted palm.
|Largely Illness Resistant||Diamond
|Australian fountain palm (Livistona australis)||X|
|Bamboo palm (Chamaedorea spp.)||X|
|California fan palm (Washingtonia filifera)||X||X||X|
|Canary Island date palm (Phoenix canariensis)||X||X||X||X|
|Chinese language fountain or fan palm (Livistona chinensis)||X|
|Chinese language windmill palm (Trachycarpus fortunei)||X|
|Date palm (Phoenix dactylifera)||X||X||X|
|Fishtail palm (Caryota spp.)||X|
|Guadalupe palm (Brahea edulis)||X|
|Kentia palm (Howea forsteriana)||X|
|King palm (Archontophoenix cunninghamiana)||X|
|Girl palm (Rhapis spp.)||X|
|Majesty palm (Ravenea rivularis)||X|
|Mediterranean fan palm (Chamaerops humilis)||X|
|Mexican blue palm (Brahea armata)||X|
|Mexican fan palm (Washingtonia robusta)||X||X|
|Pindo palm (Butia odorata; typically recognized by the misapplied identify B. capitata)||X|
|Pygmy date palm (Phoenix roebelenii)||X||X|
|Queen palm (Syagrus romanzoffiana)||X|
|San Jose hesper palm (Brahea brandegeei)||X|
|Senegal date palm (Phoenix reclinata)||X||X|
|Triangle palm (Dypsis decaryi)||X|
PETIOLE AND RACHIS BLIGHTS
Cocoicola spp. and Serenomyces spp. are the first pathogens inflicting petiole and rachis blights in palms though different fungi, together with Diplodia, Dothiorella, Fusicoccum, Macrophoma, Phoma, and Phomopsis have additionally been implicated. The ailments trigger the petiole (the slender stalk holding the leaf blade to the leaf base) and typically the rachis (the extension of the petiole with pinnae alongside its size), after which your entire leaf to die. Though usually not deadly, they will stress the palm sufficiently that different ailments kill it.
Hosts: Petiole and rachis blights primarily assault date palms and California and Mexican fan palms.
Signs and Biology: The palm typically has a lowered cover of leaves. Decrease or older leaves are first and most severely affected. Within the pinnate-leaved date palms pinnae usually die on one facet of leaf blade first, with these on the opposing facet remaining inexperienced (examine with Fusarium wilt earlier). Within the fan palms, segments within the leaf blade yellow and die in a wedge-shape sample. In each varieties of palms the petiole and rachis usually have a reddish brown, darkish brown, and even black streak that corresponds to inside discoloration of vascular tissue when seen in transverse part. Shut examination of diseased petioles and rachises would possibly reveal fungal buildings of the pathogen, particularly fruiting our bodies, inflicting the blight. Ultimately your entire leaf dies.
In distinction to Fusarium wilt on Canary Island date palms, which additionally produces one-sided leaf loss of life and impacts many leaves within the cover, usually with petiole and rachis blights only some leaves within the cover are diseased.
Whereas pinnae (of a pinnate leaf) or segments (of a fan or palmate leaf) die, they aren’t contaminated; solely the petiole or rachis is contaminated. Pinnae and segments die as a result of the pathogen has prompted vascular tissues within the petiole or rachis to die. Though the illness can transfer greater into the cover, killing extra leaves, it hardly ever kills the palm; nonetheless, it will possibly weaken or stress a palm in order that one other illness like pink rot can kill it.
Administration: Little is thought about administration of petiole and rachis blights and environmental components that favor illness improvement. As a result of fungal spores are most likely the first strategies of illness unfold and excessive humidity is probably going an vital issue encouraging illness improvement, sanitation and water administration are essential in managing these blights.
Removing and disposal of affected leaves could be a way of lowering illness unfold to close by palms. On smaller palms keep away from overhead irrigation. Preserve palms in optimum cultivation and well being as described earlier.
The fungus Nalanthamala vermoeseni (beforehand known as Penicillium vermoeseni or Gliocladium vermoeseni) causes the illness pink rot. Attributable to a weak however opportunistic pathogen, pink rot primarily is a secondary illness that impacts confused, weakened, and or wounded palms. Whereas it will possibly assault all elements of a palm, it’s most problematic within the rising suggestions, or apical meristem the place new leaves are produced, and in newly emerged leaves. Its position in inflicting trunk decay on queen palm and different species is unconfirmed.
Hosts: Pink rot can have an effect on practically all outside panorama and indoor palms in California, together with king palms, bamboo palms, some date palms, Chinese language windmill palms, kentia palms, queen palms, and California fan palms.
Signs and Biology: Signs of pink rot are variable and embody recognizing and rotting on practically any a part of the palm. Signs happen on leaf bases, petioles, rachises, blades, the apical meristem space the place leaves are produced, inflorescences (flower stalks), roots, and even the trunk though this latter incidence is unconfirmed in lots of instances. Stunting, distortion, discoloration and even loss of life of recent leaves as they emerge from the apical meristem is frequent. Pinkish spore plenty, from which the illness derives its identify, are sometimes current, particularly when protected behind overlapping leaf bases or different buildings. Brownish syrupy exudate additionally could be current. Contaminated crops weaken and decline and finally can die, particularly if the apical meristem is attacked.
Like diamond scale, illness severity steadily might be cyclical in giant, established palms. For instance, the pathogen can infect rising suggestions and spear leaves, the youngest leaves that haven’t but unfolded, throughout the cooler, moist climate of winter and spring when leaf manufacturing and progress are gradual. This state of affairs is very true of California fan palms. As climate warms in late spring and early summer time and the winter-produced spear leaves push out and unfold, earlier injury seems though the illness not is lively. The palm then produces an abundance of disease-free leaves throughout vigorous summer time and fall progress. As leaf manufacturing and progress gradual within the winter, the illness turns into extra lively once more. This cyclical nature and the way in which palms produce leaves sequentially within the crown typically ends in a particular sample of some broken leaves repeatedly distributed amongst in any other case wholesome ones.
Cultivation or environmental circumstances can stress or weaken palms, making them vulnerable to pink rot. These circumstances embody:
- palms planted too deeply
- transplanted palms, particularly when completed on the incorrect time of yr, resembling the autumn and winter
- extreme irrigation
- poor drainage
- poorly aerated root zones
- improper diet
- pest infestations and different ailments and problems
- chilly climate or freeze injury
- inappropriate pruning and leaf-base removing
- poorly tailored species
Though not all the time vital for illness improvement, wounds facilitate pathogen entry and improve an infection dangers. Keep away from injuring palms when pruning and performing different horticultural procedures. Particularly keep away from untimely leaf-base removing, which might tear and wound the trunk, inflicting everlasting injury and rising an infection danger.
Excessive humidity and temperatures of 65° to 80°F favor the pathogen and illness improvement. Palms grown in cool, humid, coastal areas are extra vulnerable to pink rot than these grown in hotter, extra arid, inland websites. Pink rot is unusually problematic on bamboo palms produced in humid greenhouses nurseries, particularly if overhead sprinkler irrigation is used; in these conditions it causes leaf and trunk rot, bleeding, wilt, and loss of life.
The fungal spores that trigger pink rot are all over the place and may journey by wind and water; due to this fact, eradicating and disposing of contaminated leaves might be not a viable administration technique.
The even handed and non permanent use of some fungicides might be efficient in suppression of pink rot till the cultivation issues stressing the palm might be corrected; nonetheless, fungicidal therapy alone will not be a viable administration technique. Fungicides might be helpful after heavy pruning to guard wounds and freshly minimize, immature tissue, or each, or quickly to guard confused palms in unfavorable environmental circumstances.
SUDDEN CROWN DROP
Sudden crown drop is a deadly illness the place, because the identify implies, your entire crown, together with the cover of leaves and higher a part of the trunk, which might weigh a number of tons, fails and drops from the highest of the trunk with little or no warning. Hidden inside decay weakened the trunk till it might not help the crown.
Though the fungus Thielaviopsis paradoxa has been remoted from Canary Island date palms which have failed resulting from sudden crown drop, it’s unconfirmed that this pathogen is the first explanation for the illness. Different pathogens could be concerned, both alone or in tandem with T. paradoxa.
Hosts: Sudden crown drop primarily impacts Canary Island date palms and, to a lesser extent, date palms.
Signs and Biology: Sadly, no conspicuous signs of sudden crown drop happen. The cover of leaves usually stays inexperienced and wholesome and the outer layer of trunk tissue (pseudobark) seems regular and intact, making this illness extraordinarily problematic to detect. Nonetheless, internally hidden decay is destroying the trunk in a roughly hourglass form, with the wholesome tissue on the within and the decayed tissue on the skin nonetheless throughout the intact pseudobark. Ample wholesome tissue stays contained in the trunk to take care of a normal-appearing cover of leaves. Ultimately, the wholesome tissue within the “waist” or constricted a part of the hourglass is inadequate to help the load above it, and the trunk fails, all of the sudden dropping the crown of leaves and connected portion of trunk.
Though cultural components, together with drought stress, might promote illness improvement and severity in Canary Island date palms, the intensive use of chain saws to prune leaves and to form and sculpt “pineapples,” the ball-like mass of persistent leaf bases just under the leaves, and particularly to “pores and skin” or “peel” trunks of outdated, persistent leaf bases can create gaping wounds that facilitate pathogen entry and onset of decay. Thus, annual screening or testing is crucial for detection.
Often pruned Canary Island date palms, particularly these with a historical past of chain noticed pruning, are essentially the most vulnerable to sudden crown drop. Search for palms with sculpted pineapples or, particularly, skinned or peeled trunks under the leaves the place the floor seems easy, devoid of elliptic leaf base scars, and even straight-sided as an alternative of spherical, positive indicators of previous chain noticed use. Not solely can such extreme pruning create entry websites for the pathogen, the everyday place of such pruning, excessive up on the trunk the place tissues have but to realize anyplace close to their most power and resistance to decay, will increase the chance of decay and crown drop.
Administration: Keep away from pruning practices resembling sculpting pineapples, and skinning or peeling trunks of outdated leaf bases, which usually create giant wounds that facilitate pathogen entry.
Completely clear and disinfect all pruning instruments previous to work on every palm by vigorously brushing them to take away sawdust and different particles. Disinfect the instruments for 10 minutes in a 1:Three pine-oil-to-water answer, 1:1 answer of family bleach and water, or warmth the noticed blades for no less than 10 seconds per facet with a handheld butane torch. Clear and disinfect as described all instruments used within the root zones of Canary Island date palms, resembling shovels, spades, rakes, hoes, and weeders, which might unfold the illness.
For detection of sudden crown drop use a heavy rubber mallet or sturdy picket follow sound and pay attention for hidden decay within the higher a part of the trunk. When sharply struck, wholesome tissue emits a stable, sharp, resonating tone and the stick bounces again shortly. In distinction, decayed tissue emits a low, boring thud when sharply struck and the stick doesn’t bounce again with a lot drive. If sounding detects decayed tissue, then the realm might be probed with a protracted, sharp, slender device to find out extent of decay. If decay is intensive, the palm must be eliminated.
As a result of a Canary Island date palm with sudden crown drop will finally die and poses an excessive and imminent hazard, it’s prudent to take away it as quickly as potential following the identical procedures outlined earlier below Fusarium wilt to forestall the unfold of pathogens.
WARNING ON THE USE OF PESTICIDES
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Elliott ML. 2015. Petiole (rachis) blight of palm. Univ. Florida Inst. Meals Agric. Sci. Ext. Publ. PP-221.
Elliott ML, Broschat TK, Uchida JY, Simone GW (eds.). 2004. Compendium of Decorative Palm Illness and Issues. St. Paul: American Phytopathological Society Press.
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Hodel DR. 2009. Palms within the panorama. Illnesses Half II. Western Arborist 35(2):20–27.
Hodel DR. 2012. The Biology and Administration of Panorama Palms. The Britton Fund, Inc. Western Chapter, Worldwide Society of Arboriculture, Porterville, CA. 176 pp.
Pest Notes: Palm Illnesses within the Panorama
UC ANR Publication 74148
AUTHOR: Donald R. Hodel, UC Cooperative Extension, Los Angeles County
TECHNICAL EDITOR: Okay Windbiel-Rojas
ANR ASSOCIATE EDITOR: AM Sutherland
EDITOR: B Messenger-Sikes
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