Yellowing leaves on camellia

Need help with what to do in your garden?

Q Why are the leaves on my camellia turning yellow?

A There are a number of reasons for this. Below are a few of the more common ones:

Lime-induced chlorosis A common cause of yellowing is lack of iron or manganese. This is normally worse on alkaline soils. An ericaceous feed that contains chelated iron or manganese may help to ease the problem. But, long term, moving the plant into a container may be more realistic. Use an ericaceous compost.

Virus Leaves and branches become mottled with yellow or white markings, and flowers exhibit ‘broken’ or mottled colouring. There is no chemical treatment for this disease: just prune out the affected parts.

Caption: Yellow leaves on camellias can be caused by different problems

Overwatering Root death leads to reduced uptake of nutrients. Cutting down on watering and applying a foliar feed may save the plant.

Phytophthora root rot Sadly, this fungus cannot be treated and can kill camellias. Reduce the risk by providing a well-drained soil. Look out for dead patches of bark near soil level. If you have to get rid of an affected shrub, don’t replant in the same spot.

Identifying And Fixing Problems With Camellias

Even under the best of circumstances, problems with camellias can and do occur. However, learning how to identify and fix common camellia problems before they become an issue is the best solution.

Common Camellia Problems

Several diseases affect camellia plants. The most common include petal blight, canker, leaf gall, root rot and camellia yellow mottle leaf virus.

  • Petal blight affects camellia flowers, causing them to turn brown. This fungal disease generally occurs in spring and is usually due to abundant moisture. Petals develop small brown spots that quickly enlarge until the entire bloom has browned. The infected flowers will usually drop within one to two days. Dark brown veins in the petals are a good indication that a camellia plant is suffering from petal blight. Pull off and dispose of infected flowers and treat with a foliar fungicide every one to two weeks.
  • Canker disease can be identified by the sudden wilting of branches along with gray colored blotches. The infected bark usually splits open, giving way to pinkish cankers. Branch tips may also die back. Once infected, prune and destroy cankerous branches, cutting several inches below affected area. Planting camellias in well-drained soil usually helps prevent canker. Spraying with fungicide may also help.
  • Leaf gall, or Oedema, is often the result of fungus due to overly moist conditions. Leaves become enlarged and fleshy with small greenish-white galls on the undersides. These eventually turn brown or rust colored. Remove affected leaves and spray with fungicide. Reduce watering and when planting camellias, avoid overcrowding.
  • Root rot is a fungal disease causing leaf yellowing, poor growth, and wilting followed by imminent death. Rather than healthy white roots, affected plants exhibit brown root systems. Root rot often results from over watering or poor drainage. Prevention is key to avoiding this problem.
  • Camellia yellow mottle leaf virus causes irregular yellow patterns or mottling on camellia leaves. Leaves may eventually turn completely yellow. There is no cure for camellia yellow mottle; therefore, prevention is important. As this virus is transmitted through infected stock, make sure camellia plants are obtained only through healthy plants.

Other Problems with Camellias

Other problems affecting camellia plants include pests and physiological disorders such as scale, camellia brown leaf and bud drop.

  • Scale bugs are the most serious pest that attacks camellia plants. These tiny insects attach to the undersides of leaves, which may be cottony in nature. Plants may become yellow, have fewer blooms, drop leaves, and even die. Handpicking can alleviate small infestations; however, the use of horticultural oil is often recommended to smother scale and their eggs.
  • Camellia brown leaf or sunscald is the result of too much direct sunlight. Scorched or brown leaves on camellia plants do not usually recover. Avoid planting in direct sun. If necessary, transplant to a shadier location.
  • Bud drop occurs when plants receive too much or too little water, insufficient light or extreme cold temperatures. They may also suffer from nutrient deficiencies or mite problems. Unopened buds typically drop off plant prior to blooming and may turn brown.
  • Sooty mold is common in summer and into fall. Often the result of sucking insects, like aphids and scale, the black coated leaves will eventually drop.

Camellias

SERIES 18 | Episode 26

The camellia has been with us, since it was imported into Europe from southern China, in the 17th century. It was imported as the tea plant. Our cups of tea come from Camellia sinensis – a wonderful thing but a very different plant to the ornamental ones grown in the garden.

Camellias were being cultivated in Australia within 20 years of the landing of the first fleet, so their beautifully fragile and delicate flowers have been a feature of our gardens for two centuries. If you’re looking for a hardy winter-flowering plant, it is hard to beat a camellia. With correct selection, you can have a flowering camellia, from early February, through autumn, winter, and to the end of spring. They’re quite amazing.

Camellia sasanqua ‘Shishigashira’ has absolutely wonderful pink flowers. Sasanqua camellias chiefly have white and pink flowers. They’re wonderful because they flower from early autumn into winter. They have a loose habit and make a good screen or hedge plant. I really like the way that when the flowers of Camellia sasanquas finish they just drop and the petals spread like a carpet on the ground.

If you want a large-flowered camellia then go for the C.reticulatas. Some of the flowers are the size of dinner plants. They originate in Yunnan in China, and often flower right through till November.

But when you think of a camellia it’s likely that you’re envisaging a Camellia japonica. They’re known for their upright, strong growth and the flower colours range from pink to white to red – there are many different colours and many different forms. Look out for Camellia japonica ‘Desire’, it has a beautiful form with its semi-double soft pink flowers and with darker pink on the edges of the petals – it’s just a gorgeous thing.

The Camellia japonica produces many hybrids and some 20,000 different cultivars. C.japonicas can also tend to sport. This is a horticultural term that means a genetic mutation. On the plant that Gardening Australia filmed there was a pale pink flower called ‘Cancan’, and lower down the bush was a branch with a completely different-coloured flower. That’s called sporting and means that it has now produced a totally different plant. For the serious gardener an enticing thing about camellias is that you might create a new flower and get your name in the history books. For example one called ‘Dr Percy Jenkins’, was a chance seedling that was named and bred in this garden.

Camellias will grow virtually anywhere in the country, as long as they’ve got protection from hot, drying winds. An easterly or a morning sun position is great. The only thing they don’t like is wet feet. If you’ve got a boggy spot, make sure that the soil is well-drained and perhaps plant them on a mound or a retaining wall.

Camellias don’t tolerate alkaline or limey soil, so add compost at planting time for a more acidic soil – with a pH of about 7 or less. If you ever see yellowing leaves that tells you the plant is hungry. In spring add a good handful of blood and bone and at Christmas time – Christmas Day in fact – get out and add more, plus potash. Scatter that around the roots and water it in well.

Over summer, keep the roots cool and moist, just by adding leaf mould, pea straw, or lucerne hay.

One of the great things about camellias is the many stories they bring. The famous opera, La Traviata was adapted from a tragic play, called Lady of the Camellias. And look out for a Higo camellia called ‘Dewatairin’ which was grown in Japan by the Samurai warriors, who absolutely loved the camellia for its strength and courage of early flowering. So, if you have a camellia in your winter garden, you’re not only going to get beautiful flowers but great stories too.

Why Are My Camellias Turning Brown?

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Camellias grow on flowering shrubs that resemble small trees. The flowers grow in shades of white, pink, red and purple. Diseases, pests and weather problems may compromise the overall health of camellia plants, turning flowers and foliage brown. Identifying and treating the problem is the only way to maintain plant health and avoid losing camellias entirely.

Disease

Camellia flower blight is a potentially deadly disease that will turn flowers brown. The disease begins in early spring, particularly in moist weather conditions. In early stages, camellia flower blight starts as small, brown spots. The spots grow over time to cover the flowers. The flower will die in 24 to 48 hours. Remove all flowers that have been affected by camellia flower blight, and dispose of them immediately. The blight is caused by a fungus in the soil, so clean away all mulch and debris around the plant.

Fungus

Camellia flower blight is one of the quickest and most deadly fungal diseases but not the only one that will turn flowers and foliage brown. Early root rot turns flowers yellow before the entire camellia plant begins to brown and wilt. Root rot may cause the plant to die quickly if it is not treated. Root rot fungus develops in soil where drainage is poor. Leaf gall often occurs in early spring when new growth appears on camellia plants. Young, new leaves will become distorted and turn pinkish or whitish in color. Later, the abnormal areas of the leaves rupture and leave behind white spores that harden and become brown. Leaf gall creates no significant damage but does discolor the plant. Remove all areas of the plant affected by leaf gall, remove all fallen leaves around the plant and destroy it all.

Tiny scales feed on camellia foliage, sucking the nutrients right out of the leaves. Heavy feeding will weaken the plants and create wilting of the leaves and flowers. Tea scale is particularly damaging to camellia. Early symptoms appear as yellow blotched on leaves. Remove all foliage affected by scales by hand, and treat the plant with pesticide.

Weather

When flower buds turn brown and drop prematurely from the camellia plant, bud drop is the culprit. Extreme weather changes may lead to bud drop. Plant camellias in an area where they will not be too wet or too dry, and protect the plants from freezing weather. Plant camellias in partial shade to protect them from very hot sunlight in the summertime. Bud drop may also be caused by poor soil drainage or a lack of nutrients in soil. Bright sunlight may also cause sunscald, which is something like a sunburn on the plant. Leaves and flowers may appear bronzed or burnt when sunscald occurs.

Camellia Pests and Diseases

by Andrew Raper

Camellias’ reputation for being hardy and sustainable garden shrubs is well deserved. However from time to time some seasonal condition or insect event may cause concern in the home garden. Before reaching for the most lethal or toxic chemical to eliminate the problem, consider which solution will have the smallest impact on you and your beneficial friends in the garden. Most insecticides cause a blanket kill effect (non selective) on all the insects, spiders and mites wiping out both good and target bugs. This is now known as a vacuum effect that is unfortunately recolonised by the bad bugs first. Camellias Victoria recommends ‘integrated pest management’ practices be employed rather than a “ground zero” approach to pest control, i.e. tolerate minor infestations for the sake of friendly predators such as lady birds, praying mantis, native birds, etc.

MOST COMMON INSECTS
Aphids

These small and easily recognised insects are usually associated with new growth. They can be green, black or brown in colour and may occur on flower buds during autumn and even winter and new growth in spring. Aphids are sucking insects whose damage weakens the host camellia and are often associated with the spread of more serious diseases. Squashing them between your fingers can attain control of small infestations. Some people recommend squirting with a strong spray of water, be cautious, this may only be spreading the problem further around the garden. For chemical control, you should ask for a modern low toxic and, most important, selective insecticide eg. ‘Confidor’.

Thrips

This pest invades our gardens in spring and early summer, they use favourable wind currents to cover large distances to spread through our gardens. Control, same as for aphids.

Caterpillars

Two types are found in quantities which may require more than an occasional walk past squeezing the rolled up growth tips. They are the cabbage white and the light brown apple moth larvae. For a major outbreak requiring spraying, use a chewing insect spray, eg ‘Carbryl’. A biological spray ‘Dipel’ may be applied, this has proven effective in orchards and vineyards. Whilst it is not 100% effective once the microbes are active a high level of caterpillar control is achieved.

Scale
May be found on camellias where plant vigour is not strong, also large containers, heavy shade and over dry conditions seem to promote scale. Scales are small roundish insects that may be found on the underside of the foliage or on the stems. They can be white, brown or black and are often found in conjunction with ants. The ants offer protection to the scales and also aphids in exchange for excess sap that they exude that the ants use for food. Control of the scale will also make the ants move on. Use “Pest Oil” or “Malascale” as recommended and use a follow up spray to kill off any secondary hatchings.

Weevils
European garden weevil damage is easily identified by tell-tale scalloped chew marks around the outside of the leaf. The damage is unsightly but usually localised to a small area of thegarden. Weevils are nocturnal so identification can be tricky as catching one isn’t easy. The traditional method is by far the easiest using trap boards. Weevils only move under cover of darkness so a plank (50cm x 15cm) strategically placed near the affected plant flat on the ground gives this villain a hiding spot. You will find your weevil waiting for you in the morning. Chemical control would be a residual chewing insecticide, eg. “Carbryl”.

Mites

Two-spotted Mites
Two-spotted mite (also known as red spider mite) may choose camellias as a host over the hotter months. This seems more common in garden situations where dry, still conditions are constant particularly along fences and in shade houses where over-crowding occurs. Chemical control of mite has become nearly useless due to chemical resistance of the mite. Changing the host environment is beneficial, more direct watering of the foliage, pruning overhead branches to reduce shading is also effective.

Eriophyid mites

They are so small and difficult to see without some magnifying device that they often go undetected. They are wormlike and range in length from 0.1 to 0.3 mm. They also have considerable reduction in body structure; the two pairs of hind legs and most body setae have been lost and the front legs are reduced. The symptoms they produce include odd colour patches on leaf surfaces, leaf margins that roll inward or downward, swollen and distorted leaves, galls, russetting, and “witches brooms”. The symptoms are often confused with the symptoms of growth regulator or herbicide damage.

Biological Control: Predatory mites are voracious eaters will devour the imbalance and then establish their own balance in your garden. Note: predatory mite are very susceptible to many chemical sprays, use with caution. Predatory mites can be bought by mail order and sourcing through the internet is a good way to access them.

FUNGAL DISEASES
Sooty Mould
This unsightly black sticky substance is actually growing on the residue products secreted by aphids and scale. Identification and elimination of the pest as previously discussed will correct this situation, followed by an application of white oil or pest oil to eliminate the sooty mould spores.

Botrytis (Grey Mould)
This is one of the most common airborne fungal diseases affecting camellias. It causes premature aging of blooms and brown spots especially in the centre of flowers. To confirm the presence of botrytis turn the affected flower over and look for grey hairlike growths around the base of the flower. Botrytis may also result in pink circles on the front of the flower as in roses. Botrytis is a seasonal event commencing around late April with sasanqua flowering and continuing throughout the entire season. Cool, moist and very still conditions favour botrytis and, infrequently, these are constant enough to make this disease a big problem for home gardeners. Keeping potted plants spaced and maintaining affected bushes trimmed to allow better air circulation make it unlikely problems will occur. If chemical control is required most rose fungicides such as Triforine or Mancozeb contain agents to combat Botrytis.

Camellia Dieback and Canker: (Glomerella cingulata.)

This is one of the most serious of all camellia diseases and is caused by the fungus Glomerella cingulata. Leaves on affected branches suddenly turn yellow and wilt. Branch tips usually die. Gray blotches appear on the bark and stem, and then sunken areas (cankers) develop, eventually girdling the stem. Parts of the plant above the stem canker lose vigor, wilt and die. Damaged plants show more symptoms during hot, dry weather.

Prevention and Treatment: Keep camellias as healthy as possible. Plant in a well-drained acidic soil, avoid wounding and fertilize properly. Remove diseased twigs by pruning several inches below the cankered areas. Disinfect pruning tools between all cuts, using a solution of one part household bleach to nine parts water. There are fungicides available to treat the affected areas which can be applied during wet periods and normal leaf drop periods to protect fresh leaf scars from infection. Apply all chemicals according to directions on the label.

Leaf Gall: (Exobasidium camelliae)

This disease is more common on sasanqua varieties of camellia (Camellia sasanqua) than on Camellia japonica. It is caused by the fungus Exobasidium camelliae. Leaf galls are most often observed during the spring flush of growth. New shoots and leaves become enlarged, thickened and fleshy, and appear abnormal. The color of the affected areas turns from light green to nearly white or pink. The galls later rupture on the undersides of the leaves revealing a whitish mass of spores. The galls eventually harden and become brown. Plants are seldom severely damaged.

Prevention and Treatment: Remove and destroy young galls before the lower leaf surfaces turn white and spores are released, or the disease will be worse the next year. Rake up and remove fallen leaves. Avoid wetting the leaves when watering. Humid, moist, shady conditions favor gall formation.

ROOT ROTS
Phytopthora and Pythium
Young cuttings and seedlings are especially prone to these root rot diseases particularly when in potting mixes rather than the garden. The use of “Fongarid” as a protective drench is a worthwhile practice for all propagators to make routine, even if only a few cuttings are attempted a year. Propagation trays or pots should be washed down in household bleach at recommended rates for floor cleaning.

In larger plants root rots are more likely to occur as secondary issues taking hold only if there are pH issues or micro nutrient problems. Regular re-potting even if no increase in size is required (say every second year), fertilizing regularly especially in pots in spring and autumn with a complete fertilizer, and maintaining a soil pH at a range of 5.5—6.5 will keep healthy camellias.

Camellia Petal Blight
(Ciborinia Camelliae)
Just the mention of this disease leaves Australian camellia growers in a cold sweat! At present camellia petal blight is not in Australia, however our friends in New Zealand and the UK are the most recent additions to the list of infected countries, which includes China, Japan, USA and most of Western Europe. This fungus disease uses air currents to spread, its spore landing on camellia blooms, turning them brown and to mush in as little as a day. The devastated bloom falls to the ground where the full cycle of the fungus is completed and ready for repetition next season.

Chemical control has to date been almost useless as chemicals are only in the developmental stage or very expensive. Even cleaning up the spent blooms will only help a little as wind spread has been found to be a massive 300 kilometres a season. The greatest risk to Australia is an illegal imported plant being brought in outside our stringent quarantine services. Soil contaminated shoes are also a major threat so declare your shoes to the Quarantine officer at the airport for inspection. They are happy to assist you with this.

OTHER AFFLICTIONS

Bud Drop:

Camellia flower buds may drop off of the plant before opening or the tips of the young buds turn brown.

Prevention and Treatment: Bud drop can be caused by several different factors. One of the most common causes is large fluctuations in temperature or moisture. Camellias perform best planted in areas with uniform moisture that are not too wet or too dry. Freezing temperatures can cause buds to drop before opening. Hot weather during the autumn or spring may encourage shoot growth and cause the plant to drop its flower buds. Avoid planting varieties that bloom late in the spring and plant in a shadier, cooler location to help prevent this problem. Other plant stresses due to a lack of nutrients, poor soils or drainage can cause flower buds to drop. Excessive use of nitrogeneous fertilisers such as, Blood & Bone and Nitrosol can also push new foliage growth at the expense of flowers. These fertilisers are best applied just after the flowering cycle to maximise the regrowth spurt. Camellia bud mites cause buds to develop slowly and either open late or fall off before opening. Camellias that drop their buds year after year may have a varietal problem or a problem of location that can be solved by transplanting.

Sunburn

Camellias planted in full sun or against a north or westfacing wall often get sunscald. Leaves will develop scorched or bronzed/yellow areas on the side of the plant directly exposed to the sun. Leaf-spotting fungi may infect the damaged leaves. Sunscald is a particular problem on camellias transplanted from shaded to sunny locations.

Prevention and Treatment: Prevent sunscald by planting in a shadier location or providing more shade to their present location. Once the leaves have turned brown, they will not recover. Investigation of the sun hardiness of individual camellia classes and cultivars should also be investigated. By way of example and generally speaking, Sasanquas, Reticulatas, Hybrids and many darker flower coloured Japonicas can endure more exposure. This is also predicated upon the presumption that, they live in good soil, receive adequate water and are mulched during warmer months.

Weather Damage

Frost is more likely to damage the flowers resulting in browning off and shrivelling. Although rainfall can also cause this affect, frost damage can be more pronouced. Lighter coloured cultivars are particularly suseptible to frost and weather damage and should be sited in a more easterly aspect and not facing towards prevailing, wet or frosty weather directions.

Drought: Severe drought conditions and all the stresses related to them such as, inadequate watering, heat stress can result in the underperformance of your camellias. This can equate to some levels of defoliation and poor flower-set or qualtity. However, established camellias have proved themselves to be extremely drought tolerant.

Oedema

This disorder appears as numerous small bumps on the lower side of leaves or on stems. The “bumps” are tiny clusters of cells that divide, expand and break out of the normal leaf surface. At first, they form tiny greenish-white swellings or galls. Later, the exposed surface of the swellings becomes rustcolored with a corky texture. Oedema is a condition promoted by abundant soil water taken up by the plant in warm weather. Under these conditions roots absorb water faster than it is lost through the leaves, especially when a sudden cool weather change occurs. This excess water accumulates in the leaves and then is expelled by bursting leaf cells.

Prevention and Treatment: This problem is not caused by disease or insects. Oedema can be caused by overwatering, especially during cloudy, humid weather. Water less frequently and avoid overcrowding plants to increase air movement.

Caution
It is advised that correct protective clothing be worn while engaged in remedial spraying, e.g. full body covering clothing, gloves, glasses and face mask. As a further suggestion, if children or pets are an issue, make this the last job of the day so that they are retiring from the garden as you are applying sprays. Never exceed the manufacturer’s recommended application mix rates. Do not apply sprays in climatic temperatures over 25°C. Remember that an environmentally friendly outcome is a safe and sustainable outcome.

Andrew Raper is the owner of Rhodoglen Wholesale Nursery, at The Patch, which is located in the picturesque Dandenong Ranges finging the north of Melbourne. This nursery is at the cutting edge of camellia and other plant material propagation.

Tips for growing gorgeous camellias

Camellias produce glorious winter flowers and make excellent container plants for porches or patios in dappled light. They come in a wide variety of forms, sizes, and colors. Bloom time runs from September through March, depending on the variety. Visit local nurseries now to select plants that will bloom in late winter and early spring. A healthy plant will have plenty of leaf and flower buds. Be sure to check the plant carefully for signs of pests or disease.
There are more than 250 species of Camellia, and thousands of camellia cultivars. Camellia sinensis is an edible garden plant cultivated for both black and green tea made from young leaves and flower buds. Camellia sinensis and Camellia oleifera produce a fragrant oil. Importantly, camellias provide a source of nectar and food for pollinators such as honey bees and hummingbirds during the cold winter months.
How did Camellias get here?
Originally cultivated in China and Japan, camellias were brought to England with the expansion of the tea trade in the 18th century, and were first planted in America in 1797. Pioneering settlers brought camellias west to California in the mid-19th century. In the early 20th century, camellias began to be appreciated as woodland shrubs, and this new interest led to the introduction of many new cultivars and hybrids.

What camellias like (and dislike)
Camellias are shallow-rooted and require well-drained, acid soil. Mature plants are water wise and drought tolerant. Often deep watering is needed only once a week in the summer, while long-established shrubs may survive with little to no summer water at all. If it is a dry winter, water is needed when the soil feels dry. Prune for shape and health when blossoms end.

Camellias are winter-hardy plants that thrive in our Mediterranean climate. They bloom best when sheltered from full sun and drying winds.
They benefit from an acid, phosphate-rich fertilizer applied in March, April, and May. No summer feeding is needed. A final feeding can be given in mid-fall before bloom. Avoid over-watering and over-feeding. When watering, be sure to give them a deep soaking to leach accumulated salts out of the root zone. In addition, chelated iron may be used if chlorosis is a problem. Read the package label and follow the recommended rates.

Pruning should be done after flowering, in the summer or fall. Remove any dead wood or weakened branches. Thin out center of plant to allow for better air circulation.

When planting a camellia, cultivate the soil to eight or ten inches deep and mix in plenty of organic matter to encourage root growth and development. Place the plant so that the root ball is level with the soil surface. Never allow soil to cover the base of the plant. Keep the root zone evenly moist, cool, and weed free by mulching with two to three inches of organic mulch.
Camellias are slow to establish because they are slow growing and have shallow roots. Older plants will grow in full sun when their roots are shaded by leaves.
Camellia japonica and Camellia sasanqua: what’s the difference?
The two types of camellias you will encounter at nurseries are Camellia japonica and Camellia sasanqua.
Camellia japonica is the “standard bearer” for camellias, bearing large, rounded leaves, a tight growth habit, and large flowers in shades of white, red or pink. These blossoms are three to five inches wide. The flowers may be single, semi-double, or double. Camellia Japonica grows to a height of 25 feet, but is usually kept at six to twelve feet. Different varieties have bloom times ranging from September to April.

Camellia japonica ‘Bob Hope’ Photo: GardenSoft Camellia japonica ‘Spellbound’ Photo: GardenSoft

Camilla sasanqua has an open growth habit and can be upright and bushy or low and spreading. It has small, narrow, pointed leaves, and small, fragrant, single, white, red, or pink blossoms two to three inches across. It blooms in December. Camellia Sasanqua’s height ranges broadly, from just one foot to over twelve feet high. Although its flowers are smaller than and not as long lasting as those of Camellia japonica, it blooms profusely and can take more sun.

Camellia sasanqua ‘White Doves’ Photo: GardenSoft Camellia sasanqua ‘Hana Jiman’ Photo: GardenSoft

Problems to avoid
A common fungus disease of camellias is Camellia petal blight, or Ciborinia camelliae, which affects all cultivars of Camellia japonica. Camellia sasanqua is infected less often in California.
Disease development requires cool, moist conditions in early spring just before or during early bloom. The disease first appears as small, water-soaked spots or as large, single, and brown to tan areas in the flower center. During proper weather conditions the smaller spots rapidly expand to encompass most of the bloom. Petals are quite slimy to the touch. The fungus carries over to the next season on fallen, diseased blooms. Prevention of the disease through proper sanitation is preferable to use of fungicides. Remove all infected flowers and discard. Rake up and dispose of old mulch, as disease spores can survive here as well.
All camellias benefit from mulch during the winter. But do not mulch with old blooms or leaves, as these can harbor a fungus that produces camellia blossom rot. This fungus infects the expanding flower buds and flowers and can result in blossoms turning brown before the flowers open. DO NOT add camellia blossoms or leaves to compost. Instead, throw them away with garbage waste.
Here’s where you can learn more about camellia petal blight.

Camellia petal blight is a fungus that causes small, brown, irregularly shaped blotches on petals. photo: Jack Kelly Clark

Solutions: how to keep camellias healthy
Prevention is the best control. Remove the top layer of potting soil when new plants are purchased and replace it with pathogen-free soil. Plant camellias in a well-ventilated location and avoid overhead irrigation. Pull off infected flowers as they appear and collect fallen blossoms and dispose of them in a covered location away from camellias.
Do not add camellia petals or leaves to mulch that will be used around camellia, even if it has been composted. It is difficult to expose camellia debris to the 140°F required to kill all of the Ciborinia propagules by composting.

Each year, when blossoms are no longer present, apply a fresh layer of pathogen-free organic mulch and maintain a 4-inch layer of organic mulch beneath and somewhat beyond plants to suppress pathogen spore production. Remove fallen petals and other camellia debris before applying fresh mulch, but otherwise avoid moving or disturbing existing mulch where fungi may be present. Keep mulch thin near the trunk or several inches away from the trunk.

Spraying an appropriate fungicide during bloom can help to reduce infections. Depending on the fungicide, reapplication may be needed every 10 to 14 days while conditions remain suitable for the pathogen. Use fungicides only in conjunction with recommended sanitation and cultural practices.

All camellias benefit from mulch during the winter. But do not mulch with old blooms or leaves, as these can harbor a fungus that produces camellia blossom rot. This fungus infects the expanding flower buds and flowers and can result in blossoms turning brown before the flowers open. DO NOT add camellia blossoms or leaves to compost. Instead, throw them away with garbage waste.

Original text by Barbara Ott and Mary Bernard
Edited for the Leaflet by Jane Scurich

Camellia Troubleshooting

You can’t help but be attracted to the beauty of camellias and other acid loving plants. It makes them one of the most popular plants in New Zealand gardens.

Here is a quick guide to pests and diseases that camellias can be prone to.

Aphids

These small and easily recognised insects are associated with new growth. May occur on flower buds during autumn or even winter and new growth in spring.

Symptoms: Clusters of insects on young growth
Remedy: Spray with Enspray Oil at 2 weekly intervals

Mites

Mites are another insect that can be found under the leaves of camellias as very fine dust like substance.

Symptoms: Leaves yellow (stippled or mottled) and dehydrated in hot dry weather Remedy: Spray with mite killer

Thrips

This pest invades our gardens in spring and early summer, they use favourable wind currents to cover large distances to spread through our gardens.

Symptoms: Leaves silver and dry. Brown-black specks appear on underside of leaves
Remedy: Spray with Enspray Oil at 2-3 weekly intervals through summer

Sooty mould

This unsightly black sticky substance is actually growing on the residue products secreted by aphids and scale.

Symptoms: Black sooty mould on leaves and twigs
Remedy: Spray with Enspray Oil

Leaf gall

It is caused by the fungus Exobasidium camelliae. Leaf galls are most often observed during the spring flush of growth.

Symptoms: Developing leaves and flowers are thickened, fleshy and pale green. As the thickenings enlarge, they become white or pink, with powdery appearance during wet weather
Remedy: Remove and burn all infected parts. Spray with Enspray Oil or Mavrik.

Petal blight

Symptoms: Earliest symptom is light brown or whitish coloured circular spots on petals. Spots enlarge to form irregular blotches until whole flower collapses. Petals feel slimy when rubbed between fingers. Diseased flowers dry up and cling to the plant (leaves and stems are not affected)
Remedy: Avoid overhead watering. Pick off diseased flowers. Spray at two weekly intervals with GroSafe Fungus Fighter.

Lack of fertiliser

Symptoms: Leaves yellow and/or develop dark purple tone. Slow, stunted growth
Remedy: Tui Enrich Rose, Camellia, Azalea and Gardenia Controlled Released Fertiliser in late spring after flower finishes and just before new growth starts

Soil too alkaline

Symptoms: Decline in vigour and leaves turn yellow while the veins remain green
Palmers Remedy: Fertilise with Tui Enrich Rose, Camellia, Azalea and Gardenia Controlled Released Fertiliser in late spring after flowering finishes and just before new growth starts. Do NOT use lime.

The Garden of Eaden

Why are my camellia leaves turning yellow?

Camellias are not the cheapest of plants to purchase, in fact any specimen grown in pots larger than 10 lt can easily cost upwards of a hundred dollars! So once you have set your heart on a particular specimen, bought it home and lovingly planted it up, the last thing you want to see are its gorgeous, dark green leaves turning a rather worrying and insipid yellow colour.

Camellias are native to the acidic soils of eastern and southern Asia, and while they are more tolerant to neutral and even slightly alkaline soils than their distant cousins the Rhododendrons, they will still be adversely affected in most alkaline soils.
What is Chlorosis

Why are my camellia leaves turning yellow?

The yellowing of camellia leaves is commonly known as chlorosis, and is a commonly seen condition in acid loving plants grown in alkaline soils. Chlorosis occurs when leaves produce insufficient chlorophyll – the green colored pigmentation found in almost every single plant on the planet. The reduction in chlorophyll allows other pigments to show through – hence why the yellow carotenoid pigments now show.
Chlorosis usually occurs when there is a specific mineral deficiency in the soil, such as iron or magnesium, but in the case of camellias there may well be plenty of iron and magnesium available but the roots ability to absorb them becomes inhibited when they are subjected to a high pH.
How do you treat chlorosis

Why are my camellia leaves turning yellow?

Chlorosis can be treated by spraying the leaves with soluble iron foliar feeds every 2 – 4 weeks or more effectively by lowering the soil pH. This can be achieved by applying chelates, ferrous sulphate, aluminium sulphate, or sulphur to the soil surface and allowing them to dissolve into the soil by watering and rainfall. Of course this sounds a lot more complicated than it needs to be as water soluble, acidic plant fertilizers such as Miracid or Sequestrene can be applied as a weekly liquid feed to slowly reduce the pH and increase concentrations of the available iron and magnesium. Be aware that it will take weeks and not days for the effects to show through.
A traditional method used by Victorian plants men was to add a tablespoon of Epsom salts, dissolve it in half a gallon of water and water it in at the base of the plant. You can also apply this as a foliar spray. Victorian gardeners would also bury iron nails and other such items around the root ball before planting
How to avoid chlorosis on camellias

Camellia flowers

The simplest way to avoid chlorosis on camellias is to plant them in a suitably acidic soil.
If you are not sure of the pH of your soil then you can test it using a shop bought pH soil tester available from most large plant retailers.
Alternatively you can grow camellia in large pots using ericaceous (acidic) compost or, if you still intend planting your camellia in the ground where the soil is known to be alkaline, dig a larger hole than usual and back fill with plenty of ericaceous compost.
For related article click onto the following links:
CAMELLIA JAPONICA ‘BLACK LACE’
CAMELLIA JAPONICA ‘Desire’
CAMELLIA JAPONICA ‘Mrs. Tingley’
CAMELLIA ‘ROYALTY’
HOW TO GROW CAMELLIAS
HOW TO GROW CAMELLIAS FROM SEED
HOW TO GROW RHODODENDRON SINOGRANDE
HOW TO PRUNE CAMELLIAS
HOW TO TAKE CUTTINGS FROM CAMELLIA
WHY ARE MY CAMELLIA FLOWERS GOING BROWN?
Why are my Camellia Leaves Turning Yellow?
Why are the Leaves on my Lemon Tree Sticky?
WHY ARE MY ORANGE TREE LEAVES TURNING YELLOW?
Why are the Leaves on my Peach Tree Curling?

Too flouncy, too loud, too fussy; the flowers die badly and the leaves look sickly. Camellias: are they worth the bother? Away from pots of ericaceous compost and twice monthly feedings, camellias need to feel at home in order to pull their weight, for instance in Cornwall, England:

Photography by Heather Edwards, for Gardenista, except where noted.

Right Place, Right Plant

Above: Camellia x williamsii ‘Anticipation’, with magnolia on the left and subtle rhododendron on the right.

“Look at this,” says my friend as she points to a mound of shiny yellow and crumpled brown. “The camellia’s got scorched.” Her high-maintenance shrub is defeated when it should be at its best. Though it looks sunburnt, it could be suffering from any number of things: exposure to wind, a nutrient deficiency, not enough of the right (rain) water, too much early morning sun after a night of frost.

Tip: Growing a camellia in a pot is one way of regulating its iron and magnesium uptake. Regular applications of acid fertilizer are helpful to contained camellias as well as those growing in inhospitable alkaline soil. The best thing is to grow them where they don’t need so much help.

A Green Backdrop

Above: A red camellia in Cornwall, England.

Which brings us to the next complaint. They stand out too much, with their shiny leaves and unapologetic technicolor blooms, like imitation roses far too early in the season.

Tip: Growing camellias in a less formal situation than a flower bed, with plenty of grass, amid other evergreens and with large, rangy shrubs (including camellias) will normalize them.

Plant in 3’s or 5’s

Above: Camellias growing en masse in Cornwall, against a clear blue sky.

In the right place, camellias are a different animal and not beastly at all. They share the same soil requirements as rhododendrons and most magnolias; large Cornish gardens are made of little else, besides hydrangeas for later, and outlying pines for protection against wind.

Tip: Plant camellias in groups of three to five, to create clouds of flowers (as you would with rose bushes).

Be Choosy

Above: Camellia x williamsii ‘Donation’.

The cliché of a camellia is that it’s a garish flower with bright yellow stamens and big shiny leaves. Put aside the chic white trademark of Coco Chanel and you have a flower of primary colors. Fortunately, John Charles Williams of Caerhays Castle took aesthetics into account when developing the williamsii strain, and leaves are smaller, stamens are prettier and petals drop off nicely, instead of turning mushy and brown while still on the plant.

Excellent Evergreens

Above: Camellias as giant shrubs, Cornwall.

Another camellia problem is what to do with them when their flowers have finished their prolonged and inelegant death. If grown in a pot, camellias can be carted off to a sheltered, shady spot which they’d always prefer. People who understand and love them, like Jeremy Wilson of Strete Gate Camellias in Devon, will tell you that they make an excellent evergreen backdrop to perennials later on. Where camellias grow tall and wide, in an abundance of naturally occurring acid soil, they are as useful as yew is elsewhere.

If their colors are still too much in early spring (and people who are used to a long and abundant rhododendron season wouldn’t say this), there are varieties for late summer and fall. Camellia sasanqua flowers all through the autumn until Christmas and is so much a part of the scene in Devon that it is grown as hedging.

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