3. Insects and Diseases of Camellias

The Gang of Eight Gets Buzzed and There’s War

Camellias are among the most carefree plants in our garden. Dappled shade, shelter from wind, good drainage, good compost and good mulch usually keeps them happy. Truly.

In fifteen years this Yuletide has thrived with no need for special care

In fifteen years this sasanqua camellia ‘Yuletide’ has thrived with no need for special care

But sometimes sneaky gangs of culprits stake out territories and we have to patrol. Here we are profiling five rogues, mug shots and all, so you will have no trouble recognizing these shifty characters and keeping them in their place — out of the garden.

Tea Scale

Typical example of tea scale

Typical example of tea scale

The most agressive gang member: tea scale. These are the Al Capones of the Insect Gangs, and they began to invade our Gang of Eight’s territory. Clues were ugly yellow blotches on the upper surface of leaves.

Turn a leaf over and you’ll see the gangstas, small brown females and white webby-looking males. They’ve pierced the leaves and are sucking away, and you may never catch them unless you are vigilant.

Underside of leaf infected by tea scale

Underside of leaf infected by tea scale, females barely visible as tiny brown slivers

We tried to appease them. We  plucked a few leaves. But they overwhelmed us. The more we plucked the more we found.

We lost that skirmish faster than a hare jumps a brier bush.

So we mustered the botanical tommy gun: horticultural oil spray. It’s been used in fields and gardens for almost a century to kill insect pests. Today, we use a highly refined form.

An even bigger infestation. Photo by America Camellia Society

Bad bad infestation, mostly males pictured. (America Camellia Society)

Horticultural oil works by smothering insects. It clogs their spiracles, or breathing holes. No chemicals involved. No concerns about insect-immunity developing. They never know what hit them.

It’s the safest remedy we know. Today we use Bonide All Seasons Horticultural Spray for Organic Gardening, but there are other fine products on the market.

C. sasanqua 'Apple Blossom, another carefree camellia

C. sasanqua ‘Apple Blossom’, another carefree camellia

By the time spring flowering is almost over we begin to spray. We choose a day in late March or early April when temperatures are balmy — between 40 and 80 degrees.

We avoid extremes because plants are not at their best during dry freezing weather or dry hot weather.

We mix the oil with water according to directions and spray the entire plant, especially its interior and the undersides of leaves. The plant is almost dripping when we are done. Pruning ahead of time, if needed, will open the plant up and insure the spray reaches those piercing, sucking mobs. (See Pruning and Fertilizing Camellias)

Twenty-year-old C. japonica 'Betty Sheffield' has grown too tall to spray completely,is rarely affected

Twenty-year-old C. japonica ‘Betty Sheffield’ has grown too tall to spray completely, is rarely affected by scale

Bob, who is our camellia steward,  sprays to a height he can reach, which is fine, because the tops of our old camellias don’t seem to be bothered by scale.

Perhaps the breezes up there are too rough for young crawlers searching for permanent sipping territories.

Dicey-looking plants, the young, the weak, the small, the newly planted, or the forgotten, may need extra attention.

It can take a couple of years or more before heavily infested plants fully recover. Damaged leaves will fall, and one day healthy shiny new leaves will replace them.

C. sasanqua 'Autumn Delight' is a faithful fall bloomer free from problms

C. sasanqua ‘Autumn Delight’ is a faithful fall bloomer, cold hardy and free from problems

Sasanquas  (fall bloomers) seem to be less affected by tea scale. And, happily, as camellias age, if they feel comfortable, tea scale will become only an occasional blip on their horizons.

Some growers spray like clockwork three times a year with about two months between treatments. This schedule catches multiple scale broods, but it is a lot of work. And there are other considerations.

Gardener’s Aside: Horticultural oil is safe for humans, but it kills spiders and small beneficial insects like parasitic wasps, lady beetles and green lacewings on contact. These are a camellia’s team of Untouchables; they go after the mobs naturally.

Another carefree camellia, C. jaonica 'Tama no Ura' with a striking picotee edge

Another carefree camellia, C. japonica ‘Tama no Ura’ with a striking picotee edge

Second Gardener’s Aside: Regardless of how often you spray, it ‘s a good idea to monitor plants regularly for tea scale. You’ll soon learn which plants need help and which are happy.

Checking on our camellias is not a chore for us. We like to look for new blooms, new buds, healthy new growth.

It’s a time when we can take delight, even pride, in our camellias. Many of them began life in our garden as toddlers.

Some stores refuse to carry these products, but many nursery plants are treated with neoniconides to keep them looking good for purchasers

Some stores refuse to carry these products, but many nursery plants are treated with neonicotinoids to keep them looking good for purchasers

A powerful class of chemicals  is on the market today for routine use on insects.

Neonicontinoids, they’re called, systemic insecticides that invade the entire plant– roots, leaves, flowers, even pollen and nectar. They persist for a long time in plants and soil.

Beekeepers and environmentalists are working to ban their use. We do not use these products, and we don’t recommend them, though they seem to dominate shelves in nurseries . You have to make an effort to look for kinder products like horticultural oil, as they can be marginalized in product displays, though they are still available online.

Sooty Mold

A mild case of sooty mold. UCA photo

A mild case of sooty mold. UCa photo

The Gang of Eight looked as though they’d been grown in a coal mine. Now what? First the tea scale gangs, now a coal dust gang? Good thing we’d been checking on our own Gang regularly to spot warfare. But coal dust?

Looks like it, feels like it, but it’s really sooty mold—and it starts with the gangs of greedy sap-suckers: scale, aphids, mites whiteflies.

These guzzlers suck juices from a plant and dump the goods they don’t want as honeydew. The sticky sap that drips on leaves is a signal for the next round of felons, sooty mold spores, to take over.

White flies, greatly enlarged, one of the sap-suckers. UCa photo

White flies, greatly enlarged, one of the sap-suckers. UCa photo

At least, sooty mold does not attack the leaves of a plant. The leaf merely becomes a staging area for a stubborn mat of mold. Since black leaves can’t capture sunlight, they can’t produce chlorophyll. When too many leaves plead disability, the plant is in trouble.

Fortunately,  our sooty-leaved camellias had no gangs of sap-suckers like aphids and white flies, even on tender new growth.  But oh dear! That fine male American holly standing sentinel above them looked like he’d been attacked by a chimney sweep.

C 'Chansonette', one of our originals, escaped sooty mold because it was planted under pines

C ‘Chansonette’, one of our originals, has never suffereded sooty mold because it was originally planted under pines. In fact, it is disease-free and its dense wide growth makes it suitable for a hedge

We couldn’t see members of the sipping gangs high in the holly, but we knew they were up there raining down honeydew like bird shot on our innocent camellia Gang of Eight.

Camellias, we discovered quickly, should not be planted around any plant susceptible to sippers that bring on sooty mold.

Native hollies are willing hosts to practically any disease or insect that comes along. Crepe myrtles also host suckers and sooty mold.

We tried a blast from the hose, but the mat of micro-filaments spawned by the mold spores was tough. We sprayed horticultural oil on the holly, and on the camellias for good measure. That slippery stuff may have helped clean some leaves. Or maybe not.

Grown from an air layer, this frilly pink japonica has been disease free

Grown from an air layer, this frilly pink japonica has been disease free

Sooty mold thrives in dry seasons; rains tend to wash it away.

In the end, some good soaking rains cleaned the leaves, and winter slowed the gangs of sap-suckers down.

Eventually a hurricane would finish off most of our Gang, so the on-going problem of sooty mold was solved permanently (if disastrously for us. (See Camellias Become Collateral Storm Damage.)

Twig Dieback

Leaves on branch were wilted, branch cut back, part of trunk carved away to remove fungus. Plant okay today

Drastic treatment: Leaves on branch were wilted, branch was cut back and part of trunk was carved away to remove fungus. Plant is okay today, bloomed last fall

Twig dieback is a particularly stealthy invader. Fortunately, we have lost only a couple of young plants to it. Leaves turn yellow and wilt and your first impulse when you see limp leaves is to water the plant. Don’t. It probably doesn’t need it.

Pruning cuts, lawn-mower nicks, crash landings from tree-missiles may have injured the plant and gangs of spores come drifting on breezes or raindrops to enter the tiniest wounds. Damaged branches show dark stains in their pith when they are cut.

The twig dieback gangs act fast. Symptoms spread quickly. We  cut out the diseased branch or branches until the pith is completely white, no trace of murky brown but still showing green cambium under the bark to assure us it’s still alive.

Sometimes an entire plant dies. We left this 'Lady Clare' in place and it has resprouted

Sometimes an entire plant dies back. We left this ‘Lady Clare’ in place and it has resprouted. Yellowing on some leaves is caused by too much winter sun

For good measure we cut back another inch or so. Sometimes, despite cutting and cutting until the entire branch is gone, we still see dark signs in the joint. Then we take drastic action as in photo above, and we hope.

I would be remiss if I didn’t tell you to sterilize your pruners with alcohol every time you make a cut. Shame on us, we don’t.

We have a large garden and limited time, so we take reasonable care, and give pruners periodic cleanings.

Fungicides are often recommended. We don’t use them.  They are powerful chemicals, not to be taken lightly. We can count microscopic spores in the millions. They are everywhere, hiding in litter, floating on breezes, so how do you target sprays? Instead, we do the best we can, and we hope.

When C. japonica 'Simeon was young, we could almost alwaysfind dead twigsalong its branches. Today is igrowthtwigs

When C. japonica ‘Simeon’ was young, for the longest time we were finding dead twigs among its branches. Today it is a sturdy, healthy, 15-foot shrub that produces many successful air layers

We have found what looks like twig dieback  on very young or newly planted shrubs that are probably stressed.

I suspect much of this is natural dieback caused by shaky balance between top growth and roots. It can take time for roots to begin working efficiently.

Until then, we cut out dead twigs routinely when we prune the plant. We begin to worry when we see a plant shrinking instead of growing.

By the time our small plants celebrate their five-year birthdays and develop some height and bushiness, we rarely see  dead twigs.

Camellia Petal Blight

Examples of flower, or petal blight in an American Camellia Society photo

Examples of flower, or petal blight in an American Camellia Society photo

Such a vexing problem. Fickle, too. It comes and goes with the weather. If spring is warm, humid and rainy, camellia petal blight  can turn picture-perfect blossoms into brown rag mops. During dry years, blossoms may emerge unscathed.

Here’s where it begins: millions of spores — yes, again, those pesky spores. They come neatly packaged in small hard vessels that hide in soil litter until it’s warm enough for them to escape for their spring fling.

Part of the flower blight life cycle, apothecia grow in soil and release the fungus

As part of the petal-blight life cycle, apothecia, small mushroom-like growths appear and release the fungus

Here’s how to prevent this disease. Collect the blooms as soon as they fall and trash them in a pail, not the compost pile. Then rake the mulch from underneath the plants, trash that, and replace it with fresh new mulch. In the fall,  rake up the mulch you put down in the spring, trash that, and replace that with a layer of new mulch. Got all that?

If your neighbor leaves his camellia blossoms strewn all over, well. . .

Crawling under bushes and raking up piles of mulch twice a year is not our idea of a good time in the garden. Except for occasional tidying, we always manage to be too busy to spend time collecting fallen blossoms.

Yes, we've had a few dishrags but infestations have been mild

Yes, I admit, we’ve had some dishrags, but infestations have been mild

As we’ve said before, fungicides don’t help, even though they are recommended.

How do you target millions of dust-like spores? And why would we want to use toxic chemicals  on a disease that doesn’t show up every year?

We take our chances, and we’ve been pretty lucky so far. Or maybe it’s not just luck.

Maybe it’s simply a different approach. Each year tons of dry leaves fall from the trees on our property. Tons may be an exaggeration, though when we are raking, we are not so sure.


This natural mulch is a mix of pine needles, leaves, twigs, pine cones and seed husks and . . .

Our camellias are naturally mulched with these leaves, which, by the way, are never removed or trashed. Late winter, when camellia blooms emerge, usually finds us raking piles of leaves from paths and outdoor verandas, oh, so many piles. . . directly onto flower beds, with an extra helping for camellias.

It’s win-win for us and our plants. The leaves are gone, the weeds are smothered, and the camellias have an extra mulch which will eventually settle down after rains and in time become compost. Does this casual bit of mulching interfere with the life cycle of camellia petal blight? Does the compost that’s constantly created underneath have powers to combat diseases? Those are nature’s secrets.

Gardener’s Aside: Don’t try this with wood chips. Annual heavy applications with wood chips that are solid and do not decompose quickly, will eventually build up and smother camellia roots.

C. japonica shows signs of freeze damage on its top petal

C. japonica shows signs of freeze damage on its top petal

Sometimes tips of petals are disfigured  on blossoms. Disappointing, yes, but not a sign of petal blight.

Cold snaps during bud-break will disfigure exposed tips of petals, as will strong sunshine or wind.

Fortunately, as long as some fat buds remain tightly wrapped in their overcoats during bad weather, there will be fresh, new, perfect flowers  on balmy days.

Camellia Leaf Gall

Leaf gall in its first flush of growth

Leaf gall in its first flush of growth

Tea scale gangs and flower blight may not bother sasanqua camellias, but watch out for the camellia leaf gall gangs on these fall bloomers.

It’s infrequent, but during cool damp springs new growth of camellias and azaleas can emerge thick and fleshy and bright green.

This showy growth can be attractive, and it seems like something special. Guess what causes it. Yup. Gangs of spores in the millions hiding in soil until spring breezes blow in.

Give these galls time and they become unsightly with spores that are powdery white

Give the galls time and they become unsightly with powdery white spores that fly about when disturbed

Consider the neon-green leaves your beacon for action. Remove them immediately. Pluck them by hand or prune their stems. Drop them in a plastic bag and put them in a trash can. If you delay, the leaves become dry and powdery and new spores will fly from them to lie in wait until the next cool, damp spring stirs them to action.

This gall is more annoying than harmful to camellias and it takes very little time to control by hand.

We have several sasanquas'Cleopatra' because they are carefree and we love the simple bloom. One needed drastic treatment for leaf gall

We have several sasanquas ‘Cleopatra,’ usually carefree with a simple bloom.

Only once did it cause a calamity when a four-foot ‘Cleopatra’ had so many galls it could have been a neon Christmas tree.

If I had plucked all infected leaves, it would have looked like a porcupine.

Instead I cut it to the ground, a drastic measure but one that camellias survive well. It grew back quickly and has been gall-free since.

Root Rot

This became a serious problem for us when drainage in our garden in a swamp changed from barely okay to positively poor. For a discussion of root rot,  see Camellias Become Collateral Storm Damage.

Other Pests: Voles and Deer

They are neither insect nor disease, but certainly these two mammals can deliver a one-two punch to camellias: voles by chomping roots and deer by chomping leaves. You can read more about these scoundrels in Wildlife and Camellias.

Last Words

O boy! All this talk about disease makes it sounds like camellias are always in sick bay. And they’re supposed to be carefree? Truly?

Okay okay, cut me some slack here. Have we had to deal with insects, diseases, losses in a large garden? Yes. That’s why we know so much about them. But, think about it, the only artilllery we recommend against these assassins is horticultural oil and good mulch, so you needn’t clutter your sheds with chemicals.

In thirty years of gardening on North Carolina’s coastal plain, the time spent caring for our camellias, now almost a hundred of them, has amounted to three or four days a year. The pictures of our favorite camellias you see here prove our point.

One of our favorites, C.sasanqua 'Hana Jiman'

One of our favorites, C. sasanqua ‘Hana Jiman’

The dividends in enjoyment and beauty have been vast. When the garden is brown in winter, the deep green leaves of camellias reflect brilliant sunlight. When the garden is wilted in summer, camellias stand tall and smile.

That said, tea scale will always be lurking.

Camellias in our  Garden    Siting and Planting Camellias

 Pruning and Fertilizing Camellias      Insects and Diseases of Camellias

Camellias Become Collateral Storm Damage    Camellia Recovery and Care

Air Layering Camellias    Wildlife and Camellias 

Choosing Camellias     Landscaping with Camellias    Companions for Camellias

Special for Camellia Lovers


2 Responses to 3. Insects and Diseases of Camellias

  1. Barnaby Lockyer says:

    What a jolly post! Thank you for keeping me reading with interest.

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