With lush foliage, showy blooms, and aesthetically pleasing varieties, magnolia bushes (Magnolia spp.) are beloved members of any decorative panorama.
Sadly, their magnificence will be marred when disease-causing pathogens infect magnolia bushes.
Generally magnolia ailments will be fairly innocuous, whereas different occasions 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 focus on 13 frequent magnolia ailments, and tips on how to establish and deal with them, so you’ll be able to deliver your tree again to full well being.
Right here’s what I’ll cowl:
13 Magnolia Tree Ailments
A fast reminder for conserving any plant disease-free: correct and sanitary cultivation is vital.
A wholesome plant is best at preventing ailments than one which’s already struggling to remain alive. By offering your magnolia with every little thing it must thrive, you’ll additionally enhance the chances that it’ll survive threats to its well being.
In case you want a refresher on cultivating magnolias, take a look at our rising information.
And I do know “sanitary” is a bit oxymoronic, since backyard work is of course a grimy endeavor.
However by conserving your gardening implements sterile and being conscious of how pathogens can unfold, you’ll be doing all of your magnolia bushes, and different crops in your backyard, an enormous favor.
1. Algal Leaf Spot
In case you didn’t suppose that algae may afflict land-dwelling bushes… suppose once more.
Attributable to the parasitic alga Cephaleuros virescens, algal leaf spot spreads by spores that journey through 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 colour, these spots trigger localized chlorosis, necrosis, and leaf drop, together with general plant weak point.
The causal algae overwinters in contaminated foliage and twigs, whether or not they’re on the plant or on the bottom. The next 12 months, the cycle begins anew.
Remove attainable overwintering websites by raking up close by plant detritus, and take away noticed leaves and twigs everytime you first discover signs.
Correctly area and prune your magnolia bushes to permit for satisfactory airflow inside their canopies, which alleviates these moist, humid situations that many pathogens love.
If the vast majority of the leaves in your tree are symptomatic, you’ll be able to apply a copper fungicide.
Simply know that fungicide sprays sometimes work higher as a protectant, quite than a therapy. So make an observation in your diary to spray your magnolia preventatively the next spring.
Southern Ag Copper Fungicide
Southern Ag’s liquid copper fungicide is right, and you could find it out there through Amazon.
If an contaminated tree offers you vital bother 12 months after 12 months regardless of your finest efforts, eradicating the plant and destroying it might be a sensible alternative.
2. Anthracnose
Attributable to 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 lifeless leaves and branches, the spores of the causal pathogen unfold through 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 must be eliminated as quickly as symptomatic spots are seen. Close by leaf and twig detritus must be collected and disposed of, as properly.
If the vast majority of leaves in your magnolia begin to grow to be symptomatic, a fungicide program could also be wanted – search for merchandise containing mancozeb as a major energetic ingredient.
Bonide Mancozeb Flowable
You will discover Bonide’s mancozeb flowable with zinc in 16-ounce focus out there at Amazon.
You should definitely observe the producer’s instructions for software.
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 – brought on by 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 through 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 bushes.
Prune contaminated shoots while 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 vulnerable 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 inner water plumbing.
Overwintering within the xylem 12 months after 12 months, the micro organism can entry any and all branches linked to the trunk. Leaves flip brown in midsummer, beginning with the older ones and ending with these closest to the department suggestions.
Separated from the wholesome tissue by a skinny yellow border, the brown sections regularly work in direction of the middle of every leaf, finally inflicting them to show completely 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 whole plant finally perishes.
As bacterial leaf scorch is unfold through xylem-feeding bugs similar 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 bushes are in extreme decline, take away these as properly – you might have to recruit knowledgeable’s assist for this.
You possibly can strive springtime injections of oxytetracycline antibiotics into the foundation flare, however these will more than likely solely scale back bacterium ranges sufficient to delay signs by a few weeks.
You possibly can seek the advice of an arborist in case you’re curious, however in any other case, I’d take solace in what J. R. R. Tolkien referred to 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 quite than Pseudomonas, bacterial leaf spot causes related signs to these of bacterial blight: darkish foliar spots surrounded by faint yellow discoloration, which results 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 positively 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 bushes. Typically sunken and rounded in look, cankers additionally are likely to exhibit discoloration and ooze with gnarly, sticky fluid.
Attributable to a wide range of totally different bacterial or fungal pathogens after mechanical or environmental harm, 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 through wounds, it pays to maintain your magnolias secure 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 whole department. Make your cuts a number of inches beneath the canker in direction of the trunk, to remain on the secure facet.
If cankers are on the trunk or roots, I’d advocate you seek the advice of with an arborist or plant pathologist – eradicating these takes talent that’s laborious to study as an newbie.
7. Crown Gall
I’ll say, crown galls aren’t as gross as cankers. They’re, nevertheless, quite honkin’ in dimension and conspicuous-ness.
Attributable to 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 provide a big, swollen mass of tissue on trunks, stems, and even roots that gives ample sources for the pathogen to feed on and reproduce in.
This may be dangerous to younger magnolia crops specifically, as gall improvement can stunt their development, 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 possibly can reduce out galls in the course of the dry season if you understand what you’re doing, or you’ll be able to recruit somebody with extra know-how to do it for you.
If the gall takes up a big part of the trunk, you could have to take away the whole tree if its development is extraordinarily stunted.
You possibly can study 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 seemed it up!
Attributable to 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 better look, and also you’ll discover delicate cracking on the floor of necrotic leaf tissues, particularly in older spots.
Usually in spring or fall, spores produced by the fruiting physique of the fungus unfold through wind and water, so it pays to observe your watering, particularly throughout cool and overcast situations.
Keep away from splashing leaves with irrigation, however in case you do find yourself wetting the foliage, water early sufficient for it to dry earlier than dusk.
This illness is just a little unpleasant and hinders photosynthesis, so you need to prune contaminated leaves while you see them.
9. Phytophthora Root Rot
Affecting many various bushes and shrubs within the panorama, Phytophthora root rot isn’t any joke. Not that any of those ailments are, however this one falls particularly flat, humor-wise.
As moisture-loving water molds (oomycetes), Phytopthora species can survive in soil for years, offered that it stays moist.
The causal pathogen spreads primarily through water, similar to splashing rain, irrigation, or runoff – however may also journey through 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 harm to achieve entry to plant tissues.
An infection in magnolias causes the foliage to wilt, lose its vibrant colour, and in any other case seem drought-stressed.
The tree bark at soil stage will sometimes look unusually darkish, and the wooden beneath it’s going to seem an unhealthy-looking reddish-brown. After a couple of years of declining well being and placing up a struggle, contaminated bushes will more than likely perish.
Be sure that your soil may be very well-draining previous to planting. In case you’d like, planting on a raised mound of soil can assist hold water from pooling up across the roots. However guarantee that the foundation flare of your magnolia bushes 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 inside the root zone – and substitute it with a resistant tree similar 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 brought on by Phyllosticta magnoliae.
When a pathogen is called after a plant it infects, you understand that it’s an epic rivalry.
Overwintering on close by fallen plant detritus, the fungus spreads to new leaves in spring through splashing water.
On the higher surfaces of recent foliage, small purplish-black lesions kind, 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 could endure if the harm is in depth.
Moist, humid situations promote illness unfold, so keep away from wetting the foliage and watering late within the day. In case you discover any noticed leaves, take away them.
If this illness finally ends up infecting many of the cover of your magnolia and turning into an even bigger drawback than pruning can repair, early-season functions of copper fungicides can assist forestall it and restrict its unfold.
11. Powdery Mildew
It’s kinda good when the title of a illness lets you understand its signs. Exhibit A: powdery mildew.
In magnolias, the causal fungus is normally both Microsphaera penicillata or Phyllactinia corylea.
Spreading by wind in spring to early summer time, the spores trigger white powdery patches to kind on higher surfaces of foliage, which may result in curled leaves and stunted development general.
A specific drawback when days are heat to sizzling 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. In case you discover severely mildewy foliage and branches, reduce them instantly.
12. Verticillium Wilt
On the subject of killing your loved one magnolia bushes, Verticillium wilt doesn’t waste time. The one time you wouldn’t thoughts just a little dilly-dallying…
Verticillium wilt kicks off with the invasion of fungal Verticillium species similar to V. albo-atrum or V. dahlia right into a tree’s wounded roots.
You possibly can let you know’re coping with Verticillium wilt by a normal browning of the internal sapwood, do you have to reduce 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 facet of the plant.
The stress of the illness permits for opportunistic fungi to invade the tree, tag teaming it into additional decline. In a 12 months or two, the plant will more than likely die.
The causal fungi stay in soil and unfold through wind, soil disturbance, and gardening instruments.
Pressured-out roots permit for the the pathogen to enter the magnolia, so you should definitely 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 bushes are sick, take away ’em and substitute them with extra resistant bushes similar to oaks, conifers, or dogwoods.
13. Wetwood
I guess you’ll be able to guess wetwood’s signature symptom.
Also called slime flux, wetwood is brought on by the ingress of assorted micro organism into tree wounds, primarily these within the roots.
Bacterial fermentation produces gaseous and liquid byproducts, which results 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 will be accomplished about wetwood. It’s kinda just like the runny nostril of magnolia bushes, if that’s any comfort.
Aren’t You Sick of Magnolia Illness?
Don’t hearken 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’ll be able to hopefully hold your magnolia bushes alive and properly for the lengthy haul.
It might be a problem at occasions, however when such attractive crops are on the road, issues are positively value addressing. Questions? Random remarks? Time to go to the feedback part beneath!
And for extra magnolia-related data, take a look at these guides subsequent: