Sweet Viburnum (Viburnum odoratissimum) is thought of as being an ironclad landscape shrub, generally a rapid, healthy grower free of insects and disease. However, this spring, many Sweet Viburnum specimens across the Panhandle have experienced varying degrees of dieback, from individual shoots to entire sections of shrubs, caused by the fungal pathogen Botryosphaeria – commonly known as Bot Rot.
Bot Rot almost always appears after some kind of major stress event that impacts susceptible plants – drought, pruning wounds, nutritional deficiencies, or another environmental stress. We haven’t been afflicted lately with any serious drought conditions and the disease occurrences are too widespread to have been a result of isolated pruning or poor plant nutrition. However, the Panhandle did experience a major environmental event around Christmas 2022 that was plenty stressful for landscape plants, a weeklong Arctic blast of extreme cold. This abrupt hard freeze event in an otherwise mild winter is my best guess for what brought about the increased incidence of Botryosphaeria we have experienced this spring.
The Botryosphaeria fungus enters plants via wounds – in this case one probably caused by cold – and begins destroying the plant’s vascular system in the area. As the pathogen progresses, it eventually causes sunken cankers to appear, girdles the affected branch, and cuts off “circulation” in that stem. The first symptom of Bot Rot that gardeners notice is shoots rapidly wilting and exhibiting a blighted appearance, with brown, dead leaves holding onto affected limbs. Unfortunately, dieback isn’t always limited to individual shoots and can spread back into plants to eventually encompass whole branches. Entire plants dying from Bot Rot infection is not uncommon.
While there aren’t any fungicides that are effective in controlling or preventing Bot Rot, gardeners can arrest its spread by pruning out infected branches. To completely rid the plant of the fungus, make sure to prune 4” or so below the last infected plant tissue (symptomatic tissue will appear dark and discolored; healthy tissue will appear light and greenish). After pruning each affected plant, it is important to sanitize pruning equipment with either a 10% bleach solution or 70%+ isopropyl alcohol to prevent spreading pathogens to other healthy plants! Plants that have been irreparably disfigured by Bot Rot or outright killed may be pulled and discarded offsite.
While this year’s Bot Rot infestation has been extremely frustrating and similar future freeze events can’t be ruled out, gardeners should not give up on Sweet Viburnum, an excellent specimen or screening shrub. Keeping plants healthy with proper pruning, good fertility, and adequate irrigation is the best defense to ward off future infection when we experience harsh environmental conditions! For more information on Bot Rot, Sweet Viburnum, or any other horticultural topic, contact your local UF/IFAS County Extension Office! Happy Gardening.
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!
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 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.
The shorter days and cooler temperatures of autumn bring on changes in our shrubs and trees.
Most people expect to see changes in leaf color in deciduous trees and shrubs during fall. But some people become concerned when the leaves on certain evergreen plants begin to turn yellow with the change in the seasons. For many plants this is normal.
Azaleas may lose a few leaves now. These are the older leaves on the branches near the center of the plant. There is no need for alarm by the loss of a few older azalea leaves from now until spring. However, if the younger leaves, those nearest the tip of the shoot, turn yellow or brown there is cause for concern. Poor drainage, lack of water or alkaline soils may cause this condition. Be sure to keep azaleas and other ornamental plants well-watered during dry weather that may occur from now through spring.
Other plants such as gardenias, hollies and camellias may have yellowing leaves now. But as with azaleas, these are the older leaves on the stem near the center of the plant. The mature leaves will drop from the plant from now until spring. This is only the normal aging of older leaves. However, be careful to not confuse this normal process with spider mites, scale, lace bugs, nutrient deficiencies, poor growing conditions or salt injury. Just keep in mind that this normal change in leaf color and leaf drop occurs on the older leaves generally during cooler weather – it’s a seasonal change.
The leaves of sycamore trees have changed from green to brown by now. Although the sycamore is a deciduous tree, this phenomenon may not be caused by a change in day length or temperature alone. This change in leaf color in sycamores can begin in late summer. Many times, it is the result of sycamore lace bugs feeding on the leaves. By the time the damage is visible, there is little that can be done to correct the problem. However, this problem will take care of itself since sycamore trees will soon be dropping their leaves.
We do have some trees that exhibit beautiful fall foliage this time of year. A few to consider include hickory and gingko for their bright yellow fall foliage, black gum for its early display of brilliant red, purple or orange leaves and Chinese pistache for its late reddish-orange fall show. There are plenty of other good trees to consider for fall color here in North Florida such as dogwood, crape myrtle, Florida maple, sourwood, shumard oak and the list could continue.
Several times each month I am diagnosing shrub and tree problems in Escambia County that are related to the same issue, improper planting. Symptoms of this problem can be slow growth, leaf browning, and dieback. Sometimes under stressful weather conditions like drought, plants completely die.
This is a difficult sight for homeowners who have invested time and money in a tree or shrub to enhance the landscape. In some cases, the planting issues can be fixed but there are other times when a new plant will need to be installed.
The good news for homeowners is that this is a completely preventable issue. The University of Florida has excellent publications with photos about installing and caring for trees and shrubs. My Panhandle colleagues and I have also shared numerous articles and videos on proper plant installation.
Care must be taken during installation to set your plant at the correct depth. Even if a landscaper or nursery is installing the plant for you, check their work. Make sure the rootball is cut or sliced, it is not set below grade, that any straps holding the rootball are cut after it is set, and proper backfilling occurs without soil over the top of the rootball.
You don’t want to find out later in the season or even year’s later that your plant declined just because of planting problems.
The interest and use of native plants in the landscape in Florida and the southeastern U.S. has increased significantly over the last 20 plus years. There are many benefits for including them in our landscapes including creating a wider biodiversity and enjoying the multitude of support for butterflies, wildlife, and unique color displays.
Choosing the plant species that works in landscape sites requires a few considerations like being adaptable to the site conditions, soil type and preparation, understanding the plant establishment needs, and finding plants regionally to your area.
Develop a landscape plan that includes addressing soil and site preparation as many landscape sites are altered during the construction phase with the soil being drastically changed. In Florida many sites need soil backfill to raise the elevation for buildings, drive or parking areas to remain above flood challenges. Choosing the right plant for the right place will need to include understanding the plants’ growing environments. Do the plants perform best in well-drained drier areas or moister situations with slight flooding tolerances? Native plants have acclimated to specific soil settings over thousands of years. When selecting the plants for your landscape, perform a site analysis with soil texture, drainage, soil pH, hours of direct intense sun or shade in the growing season, air circulation in the growing area, and growing space available. Doing your homework first can save a lot of money and frustration later. Visit the local nurseries to see plant availability. Just remember many landscape settings do not always match the natural habitats where many of these plants are established in nature.
Soil amendments will likely be needed to improve the soil conditions and provide optimal plant establishment and performance. Most often the soil that brought in is sandy and nutrient poor with little to no organic matter. In addition, the soils are compacted by heavy equipment during the construction phase. These factors can create native plant challenges leading to poor growth and shortened plant life spans. When the soils have been addressed according to plant needs the selected plants can be placed and the fun part begins by following the landscape plan.
With the landscape conditions likely altered with amendments, choose plants that can establish and grow successfully in these often more difficult conditions. Florida red maples (Acer rubrum), Live Oaks (Quercus virginiana) and Sand Live Oaks (Quercus geminate) all can provide shade areas for future plantings. Butterflies attach to and feed on butterfly weed (Asclepias tuberosa) and swamp milkweed (Asclepias incarnata). Butterfly weed does well in well-drained sandy soils and swamp milkweed likes it moist. These are just a few of the many plants out there to consider. Just remember to visit your local nurseries and talk with them about native plants and availability. Enjoy your gardening adventure.