Q. Some of the leaves on my azalea and/or camellia are swollen and light green. What caused this?
A. This is caused by a fungus that has been relatively common this spring.
The fungus Exobasidium vaccinii causes leaves and flowers to become swollen or thickened, curled and waxy in appearance. This fungus causes leaves, and in some cases flower petals, to enlarge abnormally and is commonly referred to as azalea or camellia leaf and flower gall.
Exobasidium leaf gall on camellia. Credit: Larry Williams
Symptoms vary somewhat based on the host plant. In addition to azalea and sasanqua camellia, it can occur on blueberry, as well. Infected blueberry leaves turn an unusual bright red in spring with almost no swelling of tissue. With azaleas and camellias, leaves become large and distorted and eventually a white powder covers the galls. The white growth consists of spores, which is how the fungus reproduces. Galls ultimately turn brown and harden. Not every leaf will be infected. It’s more common for the plant’s lower leaves to be the most heavily infected but under humid conditions and in shaded locations galls may form on leaves throughout the plant canopy.
The disease relies on airborne spores produced in the whitish mold on the surface of galls in late spring to early summer to reproduce. The galls then form the following spring. It’s important to remove and dispose of infected leaves before they turn white with spores.
Once you see evidence of infected leaves, it’s too late for chemical control. Besides, there currently is no effective or practical fungicide to control this disease in the home landscape. But you can reduce the amount of infection on your plants the following year by pruning infected leaves and throwing them away before spores are produced. After removing infected leaves with galls, never leave them on the ground around the plants.
It’s best to bury, burn or place the infected leaves in a plastic bag and throw them away. This disease is more severe during a cool, wet spring. It’s advisable to not add to the problem by artificially providing the “wet weather” the spores need by frequently using an overhead sprinkler and keeping the foliage wet in the spring during disease development. This is exactly what this and many other plant diseases need – wet conditions. Yet another reason to water during early morning and on an as needed basis, versus allowing an irrigation system to frequently run when there is already adequate moisture from rain.
In the home landscape, the fungus does not cause any long-term problems for the plant. It just makes the plant’s leaves look ugly. The infected leaves will usually fall prematurely.
Extended spring weather with cool nights and frequent rain can be enjoyable for humans, but does strange things to plants, especially if dormant fungi are hanging around. Exobasidium vaccinii is a fungus that is believed to overwinter as spores attached to bark and bud scales. It can cause infection with the opening of buds in spring, creating odd shaped leaves and flowers that are referred to as galls. Infection is dependent on high humidity and moisture during bud break. Gall growth is due to plant cell division resulting from the stimulus of hyphal growth within host tissue. When galls are still soft, the fungus grows between epidermal cells, breaks the cuticle, and sporulates giving the gall a white cast. Either all or part of a leaf may become thickened, fleshy, and covered with a white bloom of spores. At first, diseased leaves are succulent and white, but they later shrink into hard, brown, gall-like bodies. Galls are composed of fungus-infected plant tissue. Older leaves are resistant to infection. Exobasidium vaccinii is most common in azaleas and camellias.
Photo by Sheila Dunning
But, other Exobasidium species are floating out there, and with just the right conditions they can deform other plants. That’s what caused this odd formation on one flower of a gardenia plant. In this case, the spores fused the sepals to the petals of the flower.
Photo by Margaret Stewart
While chemical controls are available, they would need to begin before symptoms appear and continue until the gall dried completely. It may be an option for the fastidious weather watcher with a good working knowledge of this disease. But, for the rest of the population, removing and destroying galls before they turn white is the best management practice to avoid having spores form and hang around until next spring. Proper pruning of the plants to improve air circulation will also reduce the chances of favorable conditions, should there be an extended cool, wet season next year.
Article Written by Khadejah Scott, Horticulture & Ag/Natural Resources Agent, UF/IFAS Extension – Wakulla County
In the serene charm of winter, a beautiful flower comes to life, adding its beautiful blooms to gardens everywhere – the Camellia, often hailed as the “Rose of Winter.” Adorned with lush, glossy evergreen leaves and a tendency to bloom even when other plants are dormant, the Camellia showcases nature’s enduring strength and grace. Consider choosing and planting camellias this January to bring this touch of elegance to your own garden.
Camellia flowers. Photo by Marisol Amador, UF IFAS
Description: Originally from Asia, camellia plants first arrived in America in 1797 and were grown in greenhouses in New England. For over two centuries, they have proven to be reliable and valuable additions to the southern landscape. Their leaves are simple, thick, serrated (notched like a saw), alternately oriented, and usually glossy. These plants produce large, multicolored flowers that can grow up to 5 inches. The common name “camellia” refers to hybrids of Camellia japonica and Camellia sasanqua. Sasanqua types bloom from October to December, followed by japonica types, which bloom from December to March.
Landscape Uses: Camellias stand out when few other plants bloom in the fall and winter. Camellia blooms look similar to roses, as well as anemones and peonies. The rest of the year, camellias make excellent landscaping plants due to their glossy, evergreen foliage, intriguing patterns and textures, and low maintenance requirements. Camellias can be used as foundation plantings, screens, accent plants, background groupings, and hedges in the landscape. Mass plantings or clusters can yield the most significant benefit.
Photo by UF IFAS
Plant Selection: You can buy camellias from nurseries, plant sales, garden festivals, and camellia displays. Plant size and form vary significantly among varieties, ranging from small to big, spreading to upright. There is also a great variety of flower shapes, hues, and conditions, and new types are released yearly. A comprehensive list with descriptions and images is available from the American Camellia Society (https://www.americancamellias.com/care-culture-resources).
Care: To ensure the longevity of your camellias, choose a suitable location with bright, partial shade, protecting them from intense afternoon sun. Plant between November and February for optimal root establishment before summer. Use mulch to retain moisture and stabilize temperature fluctuations. Camellias thrive in well-drained, fertile soil with a pH between 5.0 and 6.5. While generally resistant to drought, consistent watering is necessary during prolonged dry periods. Apply acid-forming fertilizer twice a year, and prune lightly in early spring if needed.
Ultimately, camellias stand as enduring botanical treasures and timeless landscape companions. For more information about camellias, contact your local county extension office.
Camellia japonica may be the quintessential Southern flowering plant, as it has decorated Southern landscapes with its giant winter flowers for over two centuries at this point. It wasn’t always that way though. The species took a long, winding road to the southern US, where it now enjoys its iconic garden status.
Camellia japonica is a native of the mountainous regions of east Asia. It was from there that “japonicas” were accidentally introduced to Europe in the late 1600s by British tea merchants, who mistook Camellia japonica for its very close cousin, the Tea Plant (Camellia sinensis). After a century-long stay in England, Camellias then made their way to America around 1800. As in England, Camellias were mostly grown as greenhouse flowering plants in the northern United States. However, in 1843, Reverend John Drayton of South Carolina, brought camellias to his home, Magnolia Plantation, and popularized them outdoors in the Charleston area. Many cultivars that are grown today trace their roots back to Rev. Drayton and Magnolia Plantation!
Camellia japonica ‘RL Wheeler’. Photo courtesy of Daniel Leonard.
Surviving every gardening fad and landscaping trend, Camellia’s popularity endures today for a couple of reasons. First is their winter flower display. Camellias provide a giant splash of color in an otherwise drab time of the year and there are literally thousands of japonica varieties in nearly every conceivable size, form, and color (provided you like white, pink, purple, and red) – there’s a camellia for everyone! Camellias are also about as low maintenance a plant as can be found in landscapes. It is not uncommon for camellias to persist in yards for generations without any help from gardeners. After the establishment phase, camellias can go decades without supplemental water, fertilizer, or pesticide applications in many cases – especially if they are sited in an ideal spot. Just plant these treasured passalong plants in a spot where water does not stand and that will receive some filtered or afternoon shade and enjoy the annual flowering show!
For more information on growing camellias, sourcing camellia plants for sale, or any other gardening topic, contact your local UF/IFAS County Extension Office. Happy gardening!
Residents of North Florida are no doubt familiar with camellias, the large, glossy-green-leaved shrub that flowers during the cooler seasons. Common varieties include Camellia sasanqua, which blooms from October through December (depending on variety), and Camellia japonica, which blooms January through March. Both make huge, showy blossoms that demand attention, with forms that range from wild-rose-like to stunning geometric formal patterns.
The popularity of these shrubs is not in doubt, but a cousin of theirs takes the prize as one of the most popular plants in the world. Not due to its flowers: this variety of camellia does bloom, but the leaves are most interesting to humans. It is grown in dozens of countries worldwide and global production is estimated at over $17 billion worth of these leaves. The primary product made from this plant is a beverage that is consumed more than any other drink except water. It is, of course, tea.
Camellia sinensis or “Tea Plant”. Photo courtesy of UF/IFAS.
Camellia sinensis was named by botanist Carl Linnaeus, “Camellia” to honor another botanist, Rev. Georg Kamel, who really had nothing to do with the plant at all, and “sinensis”, which means “from China”. You may be able to deduce where tea is native to.
The tea plant prefers temperatures from 65 to 86 degrees Fahrenheit, doing well in zones 7-9. It can survive freezing or slightly-below-freezing temperatures, though leaves may be damaged by frost. It enjoys moist conditions, needing around 50 inches of rainfall per year. China tea (variety sinensis), which produces smaller, more serrated leaves, prefers more light than Assam types (variety assamica), which have larger, less serrated leaves. Either variety can be grown as a shrub or small tree.
Propagation may be accomplished either by seed or cuttings; cuttings are the preferred method for reproduction, as seeds must be germinated before the seed coat hardens for best results. Caring for tea plants once established involves more frequent but light fertilization, mulching, and regular scouting for pests. Camellia sinensis is susceptible to mites, thrips, scale insects, and aphids, all of which are present in large numbers in our area. Luckily, most of these problems can be solved with an application of either insecticidal soap or horticultural oil, if control is even necessary.
Once a tea plant is large enough to harvest leaves from, it is the new growth which is plucked. The top 2-3 leaves are used either fresh or fermented for a period of time before they are brewed. Green tea comes from the fresh leaves of China type tea plants, while either China or Assam types may be used to make black tea. Black tea leaves are picked, wilted or crushed, and allowed to ferment. Fermentation darkens the leaves and is halted by heating, which also serves to dry the leaves for storage.
