With lush foliage, showy blooms, and aesthetically pleasing varieties, magnolia timber (Magnolia spp.) are beloved members of any decorative panorama.
Sadly, their magnificence could be marred when disease-causing pathogens infect magnolia timber.
Generally magnolia illnesses could be fairly innocuous, whereas different instances they’re fearsome, hard-to-beat afflictions.
However irrespective of the illness you’re preventing, there’s virtually all the time one thing you are able to do.
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On this information, we’ll talk about 13 widespread magnolia illnesses, and the way to determine and deal with them, so you possibly can carry your tree again to full well being.
Right here’s what I’ll cowl:
13 Magnolia Tree Illnesses
A fast reminder for conserving any plant disease-free: correct and sanitary cultivation is essential.
A wholesome plant is best at preventing illnesses than one which’s already struggling to remain alive. By offering your magnolia with every thing it must thrive, you’ll additionally enhance the percentages that it’ll survive threats to its well being.
If you happen to want a refresher on cultivating magnolias, try our rising information.
And I do know “sanitary” is a bit oxymoronic, since backyard work is of course a unclean endeavor.
However by conserving your gardening implements sterile and being aware of how pathogens can unfold, you’ll be doing all your magnolia timber, and different crops in your backyard, an enormous favor.
1. Algal Leaf Spot
If you happen to didn’t suppose that algae may afflict land-dwelling timber… suppose once more.
Brought on by the parasitic alga Cephaleuros virescens, algal leaf spot spreads by spores that journey by way of wind and rain to close by plant surfaces. Multiplying in quantity, the spores acquire in raised blotches or patches on leaf and stem surfaces.
Grayish-green, brown, or orangish in shade, these spots trigger localized chlorosis, necrosis, and leaf drop, together with total plant weak spot.
The causal algae overwinters in contaminated foliage and twigs, whether or not they’re on the plant or on the bottom. The next yr, the cycle begins anew.
Get rid of doable overwintering websites by raking up close by plant detritus, and take away noticed leaves and twigs everytime you first discover signs.
Correctly house and prune your magnolia timber to permit for sufficient airflow inside their canopies, which alleviates these moist, humid situations that many pathogens love.
If nearly all of the leaves in your tree are symptomatic, you possibly can apply a copper fungicide.
Simply know that fungicide sprays sometimes work higher as a protectant, fairly than a therapy. So make a remark in your diary to spray your magnolia preventatively the next spring.
Southern Ag’s liquid copper fungicide is right, and you could find it out there by way of Amazon.
If an contaminated tree offers you vital bother yr after yr regardless of your greatest efforts, eradicating the plant and destroying it might be a sensible alternative.
2. Anthracnose
Brought on by species within the Colletotrichum genus of fungi, anthracnose and its signs are about as delicate as an open-carried .50-cal revolver at a Texas gasoline station. Not very.
Overwintering in useless leaves and branches, the spores of the causal pathogen unfold by way of splashing water to close by foliage, inflicting giant, angular spots close to leaf margins.
Because the illness progresses, these spots develop a burned look, surrounded by a yellow halo of discoloration.
On higher surfaces of the magnolia foliage, the spots develop blister-like fruiting our bodies, which ooze plenty of pink spores. Finally, total leaves can flip chlorotic yellow and drop.
Foliage ought to be eliminated as quickly as symptomatic spots are observed. Close by leaf and twig detritus ought to be collected and disposed of, as nicely.
If nearly all of leaves in your magnolia begin to turn into symptomatic, a fungicide program could also be wanted – search for merchandise containing mancozeb as a foremost lively ingredient.
You’ll find Bonide’s mancozeb flowable with zinc in 16-ounce focus out there at Amazon.
Be sure you observe the producer’s instructions for utility.
3. Bacterial Blight
Blight, noun: a factor that spoils or damages one thing. Within the case of bacterial blight, that sounds about proper.
The notable signs of bacterial blight – attributable to Pseudomonas syringae pv. syringae and Pseudomonas cichorii – are small, darkish, necrotic spots, every surrounded by a yellow halo, which slowly develop into blights of bigger, extra irregular lesions that intrude with plant photosynthesis.
Spreading by way of wind, bugs, or contaminated instruments, the causal micro organism enters crops by flower buds and/or wounds, resulting in the event of sunken, contaminated cankers.
Magnolia branches with cankers can exhibit foliar and stem wilt. Oozing darkish and sticky fluid, these cankers additionally act as overwintering websites for the pathogen.
Though sometimes seen extra typically in plant nurseries than the panorama, bacterial blight can nonetheless be a harmful risk to your timber.
Prune contaminated shoots once you discover them, ensuring to sterilize your instruments between cuts.
If pruning your magnolia doesn’t present passable management, copper-based bactericides can be utilized to handle the illness in inclined environments.
4. Bacterial Leaf Scorch
A systemic, continual, and incurable illness. Gotta love these.
Bacterial leaf scorch kicks off with Xylella fastidiosa micro organism invading a magnolia tree’s xylem, which is mainly a plant’s inside water plumbing.
Overwintering within the xylem yr after yr, the micro organism can entry any and all branches related to the trunk. Leaves flip brown in midsummer, beginning with the older ones and ending with these closest to the department ideas.
Separated from the wholesome tissue by a skinny yellow border, the brown sections progressively work in direction of the middle of every leaf, finally inflicting them to show fully brown and drop from the tree.
As years cross, this browning-and-dropping happens earlier and earlier within the season, weakening and killing components of the tree in bits and items till the complete plant finally perishes.
As bacterial leaf scorch is unfold by way of xylem-feeding bugs equivalent to leafhoppers and spittlebugs, it pays to handle your native pests.
When branches begin to flip brown and die off, take away them. If total timber are in extreme decline, take away these as nicely – it’s possible you’ll must recruit an expert’s assist for this.
You may strive springtime injections of oxytetracycline antibiotics into the foundation flare, however these will almost certainly solely cut back bacterium ranges sufficient to delay signs by a few weeks.
You may seek the advice of an arborist when you’re curious, however in any other case, I’d take solace in what J. R. R. Tolkien known as “the lengthy defeat,” and take away contaminated specimens.
5. Bacterial Leaf Spot
Save for the causal pathogens being species of micro organism within the Xanthomonas genus fairly than Pseudomonas, bacterial leaf spot causes related signs to these of bacterial blight: darkish foliar spots surrounded by faint yellow discoloration, which ends up in hindered photosynthesis and decreased aesthetics.
And the “hows” of managing each in magnolias are fairly related. Prune affected plant tissue and spray with copper-based bactericides within the case of intensive an infection.
6. Cankers
We’ve talked about these already, however they’re undoubtedly dangerous and annoying sufficient to warrant their very own entry.
Cankers are necrotic, localized lesions that manifest on the branches, trunks, and/or roots of timber. Typically sunken and rounded in look, cankers additionally are inclined to exhibit discoloration and ooze with gnarly, sticky fluid.
Brought on by a wide range of completely different bacterial or fungal pathogens after mechanical or environmental injury, cankers could cause native or systemic dysfunction in foliage and bark. Foliage will flip yellow, brown, and wilted, bark will peel, and plant tissues will die.
As cankers can happen by way of wounds, it pays to maintain your magnolias protected from blades, trimmers, and tree-climbing youngsters.
Prune with warning, give root flares a large berth when working within the neighborhood, and restrict Little Timmy’s climbing to the playground till he learns to not peel away bark together with his foot placements.
Once you discover a canker on a magnolia department, prune the complete department. Make your cuts a number of inches under the canker in direction of the trunk, to remain on the protected aspect.
If cankers are on the trunk or roots, I’d suggest you seek the advice of with an arborist or plant pathologist – eradicating these takes ability that’s onerous to be taught as an newbie.
7. Crown Gall
I’ll say, crown galls aren’t as gross as cankers. They’re, nonetheless, fairly honkin’ in dimension and conspicuous-ness.
Brought on by the fun-to-pronounce Agrobacterium tumefaciens, crown galls are primarily tree tumors.
When A. tumefaciens micro organism in close by soil infects a plant by wounds, it stimulates the plant to supply a big, swollen mass of tissue on trunks, stems, and even roots that gives ample assets for the pathogen to feed on and reproduce in.
This may be dangerous to younger magnolia crops particularly, as gall improvement can stunt their progress, inhibit water and nutrient transport, and go away them top-heavy and vulnerable to breakage.
However in older magnolias, the drawbacks of galls are beauty and minor.
You may lower out galls in the course of the dry season if you recognize what you’re doing, or you possibly can recruit somebody with extra know-how to do it for you.
If the gall takes up a big part of the trunk, you will have to take away the complete tree if its progress is extraordinarily stunted.
You may be taught extra about crown gall in our information.
8. Pestalotiopsis Leaf Spot
In case you’re questioning, it’s pronounced pesta-low-she-opsis. I didn’t know the phonetics both, till I appeared it up!
Brought on by fungal species within the Pestalotiopsis genus, this illness has distinctive signs: round, necrotic, and black-bordered spots on the foliage.
Contained in the black borders, the spots are an orange to tan hue. Take a more in-depth look, and also you’ll discover delicate cracking on the floor of necrotic leaf tissues, particularly in older spots.
Sometimes in spring or fall, spores produced by the fruiting physique of the fungus unfold by way of wind and water, so it pays to observe your watering, particularly throughout cool and overcast situations.
Keep away from splashing leaves with irrigation, however when you do find yourself wetting the foliage, water early sufficient for it to dry earlier than dusk.
This illness is somewhat ugly and hinders photosynthesis, so you need to prune contaminated leaves once you see them.
9. Phytophthora Root Rot
Affecting many alternative timber and shrubs within the panorama, Phytophthora root rot isn’t any joke. Not that any of those illnesses are, however this one falls particularly flat, humor-wise.
As moisture-loving water molds (oomycetes), Phytopthora species can survive in soil for years, supplied that it stays moist.
The causal pathogen spreads primarily by way of water, equivalent to splashing rain, irrigation, or runoff – however may also journey by way of contaminated soils and backyard instruments.
It favors the cool and wet climate of early spring and late fall, and doesn’t require a wound or different injury to realize entry to plant tissues.
An infection in magnolias causes the foliage to wilt, lose its vibrant shade, and in any other case seem drought-stressed.
The tree bark at soil degree will sometimes look unusually darkish, and the wooden beneath it’ll seem an unhealthy-looking reddish-brown. After a number of years of declining well being and placing up a battle, contaminated timber will almost certainly perish.
Be sure that your soil could be very well-draining previous to planting. If you happen to’d like, planting on a raised mound of soil will help maintain water from pooling up across the roots. However ensure that the foundation flare of your magnolia timber are uncovered!
As soon as the magnolia is within the floor and rising, don’t overwater, and make sure you plant in well-draining soil.
If an contaminated tree turns into closely diseased and/or extra bother than it’s value, take away it – together with the soil throughout the root zone – and change it with a resistant tree equivalent to arborvitae, elm, or ginkgo.
10. Phyllosticta Leaf Spot
A specific foe of the southern magnolia, M. grandiflora, Phyllosticta leaf spot is a fungal situation attributable to Phyllosticta magnoliae.
When a pathogen is called after a plant it infects, you recognize that it’s an epic rivalry.
Overwintering on close by fallen plant detritus, the fungus spreads to new leaves in spring by way of splashing water.
On the higher surfaces of latest foliage, small purplish-black lesions type, finally rising in dimension and manifesting soiled white facilities whereas surrounded by chlorotic halos of yellow.
As with every leaf spot illness, photosynthesis is decreased and the tree’s well being might endure if the injury is in depth.
Moist, humid situations promote illness unfold, so keep away from wetting the foliage and watering late within the day. If you happen to discover any noticed leaves, take away them.
If this illness finally ends up infecting a lot of the cover of your magnolia and turning into a much bigger drawback than pruning can repair, early-season functions of copper fungicides will help stop it and restrict its unfold.
11. Powdery Mildew
It’s kinda good when the identify of a illness lets you recognize its signs. Exhibit A: powdery mildew.
In magnolias, the causal fungus is often both Microsphaera penicillata or Phyllactinia corylea.
Spreading by wind in spring to early summer time, the spores trigger white powdery patches to type on higher surfaces of foliage, which might result in curled leaves and stunted progress total.
A specific drawback when days are heat to scorching and nights are cool and dewey, this illness overwinters as fungal mycelium in dormant buds or as spores on fallen leaves.
Correctly prune your magnolia tree cover to permit for airflow to dry the foliage. If you happen to discover severely mildewy foliage and branches, lower them instantly.
12. Verticillium Wilt
Relating to killing the one you love magnolia timber, Verticillium wilt doesn’t waste time. The one time you wouldn’t thoughts somewhat dilly-dallying…
Verticillium wilt kicks off with the invasion of fungal Verticillium species equivalent to V. albo-atrum or V. dahlia right into a tree’s wounded roots.
You may inform you’re coping with Verticillium wilt by a basic browning of the inside sapwood, must you lower away a stem’s bark to have a look.
This an infection clogs up the vascular tissues and results in leaf and department dieback, sometimes on one aspect of the plant.
The stress of the illness permits for opportunistic fungi to invade the tree, tag teaming it into additional decline. In a yr or two, the plant will almost certainly die.
The causal fungi dwell in soil and unfold by way of wind, soil disturbance, and gardening instruments.
Confused-out roots enable for the the pathogen to enter the magnolia, so make sure to water correctly – not an excessive amount of, not too little – and watch out to not unintentionally wound the tree with pruning instruments, weed whackers, or runaway garden mowers.
I hate to say it, but when your timber are sick, take away ’em and change them with extra resistant timber equivalent to oaks, conifers, or dogwoods.
13. Wetwood
I guess you possibly can guess wetwood’s signature symptom.
Also referred to as slime flux, wetwood is attributable to the ingress of assorted micro organism into tree wounds, primarily these within the roots.
Bacterial fermentation produces gaseous and liquid byproducts, which ends up in an ooze of darkish liquid from tree crotches, bark cracks, and pruning wounds that reaches its peak in summertime.
This gross liquid additionally strikes inside a plant, inflicting wilting, defoliation, department dieback, and decreased vigor. Fortunately, plant loss of life is a uncommon incidence.
Other than avoiding wounds and eradicating severely symptomatic branches, not a lot could be achieved about wetwood. It’s kinda just like the runny nostril of magnolia timber, if that’s any comfort.
Aren’t You Sick of Magnolia Illness?
Don’t take heed to Disturbed’s David Dramian and get “Down with the Illness.” They’re your lovely magnolias, darn it! It’s time for motion!
With this information, you possibly can hopefully maintain your magnolia timber alive and nicely for the lengthy haul.
It might be a trouble at instances, however when such beautiful crops are on the road, issues are undoubtedly value addressing. Questions? Random remarks? Time to go to the feedback part under!
And for extra magnolia-related data, try these guides subsequent: