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.
Here in North Florida, it is not uncommon to see a few citrus trees in a residential landscape. With Florida being the second highest producing state of citrus, it is not out of the normal to see them when you are out and about. They are a great option to keep a lush green aesthetic in your yard. But, what other options are there for the homeowner that wants to add some edible diversity to their landscape? In this article we will be discussing a few of the many edible landscape choices that can add both diversity and a sweet treat to your yard.
A popular edible landscape option is the rabbiteye cultivar of blueberry. The rabbiteye blueberry plant is considered easier to grow for the first time blueberry grower in comparison to the southern high bush cultivar. This cultivar thrives in acidic soils and requires a soil pH of 4.0 to 5.5. When planting, the use of pine bark mulch is a great organic method to satisfy the soil pH requirement. Mixing composted pine bark mulch in the soil and adding additional mulch after the bush is planted will add to the soil’s organic matter over time. Mulching also aids the establishment of young plants and moderates soil temperatures and weed control. For variety selection, mid-to-late season rabbiteye cultivars are best for Northwest Florida, as they are more cold tolerant and less susceptible to lose their flowers and young set fruit in late winter/early spring frosts. Common mid-to-late season rabbiteye’s are ‘Vernon’, ‘Brightwell’, ‘Powderblue’, ‘Tifblue’, and ‘Georgia Giant’. Because blueberry plants are not “self-unfruitful”, they will require more than one variety to cross-pollinate with in order to produce fruit. Two is great, but three plants will also encourage larger fruit set for you and your family to enjoy!
Blueberry Set Fruit, Jackson County Master Gardener Demo Garden
Another option that has steadily grown interest in the Florida Panhandle is the apple tree. There are two known cultivars of apple that are acclimated to the North Florida region due to their low chill hour requirement cold tolerance. This is the ‘Anna’ Apple and the ‘Dorsett Golden’ Apple. Apple trees will perform best in full sun locations of the yard and prefer a well-drained soil. The chilling hour requirement for these cultivars of apple are between 400-600 hours. You will begin to see the fruit ripen in the months of May to June. The ‘Anna” Apple has been compared to the well known ‘Red Delicious” that is best known in northern region of the United States. Planting should occur in early spring and planting holes should be big enough that the root system does not become over crowded from limited expansion space. There is no UF/IFAS fertilizer recommendation for the apple tree because it is not commercially produced in Florida, but generally a fertilizer such as 10-10-10 can be used.
‘Anna’ Apple, Photo Credit: UF/IFAS NFREC
The blackberry is a great choice as well for an edible landscape. There are several blackberry species that are native to Florida. Most blackberries produce thorns on their shoots, but many new cultivars have been developed as thornless. When selecting your planting location, low-lying areas should be avoided to deter from over-flooding of your plants. Blackberries thrive best in well-drained soils and high air flow and should be planted between December to February. Pollination of the plant is very important to ensure the quality and quantity of the fruit produced; blackberries range from self-fruitful to self-unfruitful depending on the cultivar. ‘Apache’, ‘Flordagrand’, and ‘Choctaw’ are a few examples of many blackberry cultivars available. The first year after the blackberry has been established, it will only produce new shoots with no berries. These shoots are called primocanes. The second year, berries will produce on these shoots and then be called floricanes. It is important to cut the tip off the primocanes after they have reached about 3 ft in height to encourage the shoot to create lateral branches. Floricanes will die off after they have produced fruit. Trellises can be used as well to encourage the plant to grow upright and off the ground.
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There are fruit types that grow well in North Florida and that do not require a lot of space. For high yields they do need a spot that gets direct sun for at least half the day. An area only 10 by 10 feet can support a gratifying amount of fruit production.
Some of the best fruit choices for small areas are rabbiteye blueberries, blackberries and muscadine grapes.
The rabbiteye blueberry is native to the Southeastern United States. Blueberries require a soil pH below 5.3. So, it’s advisable to have your soil tested to find out what the pH is before planting. Mixing peat moss into the soil can lower the pH, if needed. There are many rabbiteye blueberry cultivars. Be sure to plant at least two cultivars together for pollination. Here is a link with more information on blueberries for Florida. https://edis.ifas.ufl.edu/publication/MG359
All of the other fruits like a soil pH of 6.0 to 6.5. Garden lime can be used to raise the pH but only if you have the results of a reliable soil test indicating how much lime is needed. Your County Extension Office can help you determine how to have your soil tested.
Blackberries are productive if you select the correct cultivars. Cultivars adapted to Florida produce large, attractive fruit. Some are self-fruitful while others require a pollinator. Some have thorns while others are thornless. Some grow more erect while some have a trailing growth habit, requiring trellising. ‘Brazos’ is a late fruiting cultivar that does well in our area and does not require cross-pollination but it does have thorns. Here is a link with more information on blackberries for Florida. https://edis.ifas.ufl.edu/publication/hs104
The muscadine grape was one of the pleasant surprises found by the early colonists in the Southeastern United States. An extensive breeding program has resulted in many improved cultivars. Scuppernong is a variety of muscadine. Other popular varieties include ‘Cowart’, ‘Fry’, ‘Carlos’, ‘Summit’, ‘Higgins’, and ‘Nesbitt’. There are many others. Some are self-fruitful while others require a pollinator. There are cultivars that produce bronze, black, red or purple fruit. Some cultivars produce larger fruit, some have a higher sugar content and are sweeter. Muscadines are ready to harvest in late summer to early fall. Some mature early season, mid-season or late season, based on the cultivar. Here is a link with more information on muscadines for Florida. https://edis.ifas.ufl.edu/publication/HS100
Even though these fruit plants can be grown with limited space, they do require some care, including correct fertilization and pruning. Mid-December to mid-February is the best planting time for these fruit plants.
We have many choices of fruit that can be grown in the Florida Panhandle. For us hobby or dooryard growers, fruit trees can be an interesting crop to manage and most find it to be a beautiful addition to home landscapes. However, temperature and variety selection are key.
Blueberry Crop at UF/IFAS Plant Science Research & Education Unit. Photo Credit: Tyler Jones, UF/IFAS
Most fruit trees grown in the Panhandle are more temperate varieties, rather than tropical and subtropical fruits. Depending on the variety, winters in northern Florida may be too cold or may be too long for some fruit trees. Cold hardiness is a term used on fruit tree labels and reference guides. This refers to the plant’s ability to survive cooler or even freezing temperatures. In contrast, summer heat can also play a role in survivability. Some varieties are intolerant to excessive heat and humidity. The U.S. Department of Agriculture has developed a Plant Hardiness Zone Map that is helpful in selecting a variety of fruit tree: http://planthardiness.ars.usda.gov/PHZMWeb/. This is a standard by which gardeners and growers can determine which plants will thrive in their location. Northern Gulf County is in Zone 8b (15 to 20 degrees F), while coastal Gulf is in Zone 9a (20 to 25 degrees F).
Chilling requirement is another important topic when deciding on variety. Temperate zone fruit go through a “rest period” during the dormant months. For these fruit trees, a minimum length of time of cooler weather is needed for proper flowering to occur once favorable temperatures arrive. This rest period is essentially a reset. For the Panhandle, temperatures below 45 degrees F are known as chilling temperatures. The number of hours during the fall and winter that reach below this temperature equals the total chilling hours. For the Panhandle, this is rarely fewer than 500 hours. A plant that does not receive ample chilling will most likely be slow in bud and leaf development. Leaf expansion will be in increments throughout the year instead of in one period. On the other hand, colder, longer winters can cause fruit trees to end the rest stage early and begin to bud as soon as warmer temperatures arrive. This circumstance can cause cold injury later, as the Panhandle is historically known for late cold spells.
Citrus is a dooryard fruit, however it’s a subtropical fruit tree and not technically temperate. However, there are some varieties that thrive in the Panhandle. Another key to growing citrus, is to select varieties with different fruit maturity seasons. This way you can enjoy citrus year-round.
Some examples of dooryard fruit trees and varieties that are suitable for northern Florida are:
Information for this article can be found in the UF/IFAS EDIS publication: “Dooryard Fruit Varieties” by J. G. Williamson, J. H. Crane, R. E. Rouse, and M. A. Olmstead: http://edis.ifas.ufl.edu/pdffiles/MG/MG24800.pdf
UF/IFAS Extension is an Equal Opportunity Institution.
Normally we think of rust as something that deteriorates metal, but a number of different fungal rusts can affect plants in the garden. Rust disease can affect corn plants, cedar trees, and even blueberry bushes. Just like the broad range of plant species that can be plagued by rust, there are a number of species of rust fungal spores floating around and ready to infest your garden. This article will focus on leaf rust of blueberry.
Blueberry leaf rust on the top of a leaf. Photo Credit: Philip Harmon, University of Florida/IFAS Extension.
Leaf rust of blueberry in Florida is caused by the fungus Pucciniastrum vaccinii. Although the common name of the disease is “leaf rust”, the disease can also infect the stems and fruit of blueberry plants. The disease causes small, round spots visible on the tops of leaves. Spots will multiply and the leaves will eventually yellow and fall off. Young stems and green fruit can also become infected as the disease progresses. Bright orange lesions will form on stems and fruit as the thousands of microscopic spores conjoin. The clusters of spores are easily wiped or washed off of plant material. When spores dry out, they become airborne and can be transferred to nearby plants.
Blueberry leaf rust on fruit. Photo Credit: Philip Harmon, University of Florida/IFAS Extension
The rust fungus thrives in hot, humid, wet conditions. A number of cultural practices can be adopted to reduce disease progression and survival.
Irrigation
Disease persistence can be reduced by limiting the amount of water that contacts the plant leaves. Water the base of plants or install drip irrigation for your bushes rather than watering from overhead. If overhead irrigation is the only option, then water plants in the morning rather than in the evening. This allows the leaves to dry out over the course of the day.
Pruning
Removal of approximately 25% of the oldest canes in late winter before spring growth begins will stimulate the production of new canes and should result in plants with canes of different ages and will provide a good mix of vigorous branching and fruit production. Moderate summer pruning can also improve yield and shoot growth. When pruning, cut out vigorous shoots that are growing well beyond the desired canopy height and are in the interior portion of the bush. This will promote a more open growth habit and help with air circulation on the remaining plant material. Some vigorous canes developing from the ground and growing on the outside of the bush can be topped to stimulate branching and flower bud formation.
Mulch
Pine bark mulch helps with establishment of young plants and helps keep soil pH low in existing plantings. A layer of aged pine bark 3 inches deep extending about 2 feet out from the plants will provide a good growing medium for surface feeder roots. Pine straw can be used if pine bark is unavailable. Mulch also moderates soil temperature, helps keep weeds at bay, and adds organic matter to the soil. Make sure to keep mulch raked back about three inches away from the plant canes to provide good air circulation to the roots.
Hopefully this article has given you some tips to have a good blueberry crop for years to come. For more information on growing blueberries in Florida, please visit the University of Florida/IFAS EDIS Publication: Blueberry Gardener’s Guide.
