by Mary Salinas | Nov 22, 2021
Sugar Belle mandarin cultivar. Mix of sweet Clementine and Minneola varieties. UF/IFAS File Photo.
Florida is known for citrus and many homeowners love to grow and enjoy it. However, a devastating disease known as citrus greening or HLB has taken a toll on commercial and residential citrus since it first was discovered in Florida in 2005.
Sugar Belle is a cultivar of mandarin citrus developed by the University of Florida citrus geniuses and is tolerant of citrus greening disease if it is properly planted and cared for. Tolerance of the disease does not mean that it doesn’t get citrus greening, rather it means that this cultivar can get infected but still be healthy and productive. The fruit of infected trees is safe to eat as the bacterium that causes it does no harm to humans.
Our chilly winters can be detrimental to many kinds of citrus, but Sugar Belle can withstand temperatures down to 14°F once the tree is well established. That is good news for us in the panhandle. Even so, it is best to choose a spot in your landscape with a southern exposure, preferably with a wind block from northwest winds. Avoid low areas as cooler air falls into those areas.
Symptoms of citrus greening on leaves show a blotchy mottled pattern. UF/IFAS photo.
Make your purchase from a certified nursery to make sure you are getting the right cultivar and a disease-free tree. Spring and fall are the best seasons of the year to plant citrus. When planting, make sure to make slices in the rootball if it is rootbound or if circling roots are present. The rootball should be slightly above the ground level after planting. All weeds and grass should be removed under the canopy of the tree to as they compete for water and nutrients with your newly planted tree. Never place mulch against the trunk as it can hold moisture there and promote disease. Water often the first year until well-established; after establishment citrus has some drought tolerance and may only need supplemental irrigation in times of heat and drought.
A good quality citrus fertilizer with micronutrients is crucial for a healthy tree with good quality fruit. The first fertilization should be about 3 weeks after planting and then follow the label directions for subsequent fertilizations. Newly planted trees should be fertilized 6 times in the first year and the fertilizer should be evenly broadcast under the tree canopy.
The only pruning in the first 3 years should be the removal of suckers that grow from the base, water shoots that grow quickly and straight up, and dead wood. Be sure to clean your pruning tools before and after each tree to avoid spreading any possible disease. First rinse off any dirt or other organic matter and then use a 3% bleach solution or alcohol for sterilization.
Happy Gardening!
For more information:
UF/IFAS Research on Development of Sugar Belle YouTube
Citrus Culture in the Home Landscape
Citrus Greening
by Ray Bodrey | Sep 9, 2021
Growing Key Limes in the home landscape is not only a fun and unique addition, but is also delicious – any way you slice them.
The key lime, Citrus aurantifolia, originated in southeast Asia. Genetically speaking, the key lime is likely a tri-hybrid cross between the “odd ball fruits”, known as citron, pummelo and a microcitrus species, Citrus micrantha. There is little commercial key lime production nowadays in Florida, but the fruit remains a very popular landscape option.
The key lime is a small, bushy tree that makes harvest and pruning a breeze. Like most citrus, it’s self-pollinating. The key lime is also an ever-bearing fruit, so there is no real seasonal harvest. The tree could technically bloom any month of the year. There are very few varieties, as trees mostly come from true seed or air layering.
Key Lime fruit at various degrees of ripeness. Photo courtesy of Ray Bodrey, UF/IFAS Extension Gulf County.
Climate is an important factor when deciding to plant a key lime. They are sensitive to cold temperatures, especially below freezing. For the Panhandle, it’s wise to keep key lime trees as patio citrus. In other words, keep the trees in pots so that they can be moved indoors for protection during the winter months. In the ground, trees should be planted in an area where there is a significant wind block. Once a few years have passed and tree has become more mature and acclimated to the environment, they may be able to survive on their own, though it is recommended to cover the tree under sub-freezing temperatures. However, it is important to remember that sunlight is a catalyst for citrus fruit production, be sure to plant the tree in an area with full sun.
The usual suspects of citrus insect pests apply to the key lime also. Citrus leaf miner and mites are the most common culprits. Horticultural and insecticidal oils will certainly help to combat these threats. For planting, key lime is well adapted to a variety of soil conditions in Florida. Be sure to water newly planted trees every other day for the first week and then one to two times a week for the first couple of months. Water periodically after that, making sure the soil doesn’t stay completely dry for long periods. A 6-6-6 fertilizer works great for the key lime. Please follow the fertilizer schedule found in the UF/IFAS EDIS publication, “Citrus Culture in the Home Landscape” by Robert E. Rouse and Mongi Zekri: https://edis.ifas.ufl.edu/pdf/HS/HS132/HS132-11822781.pdf
A final interesting thing about the key lime is the ripening stages of the fruit. Because key limes are ever-bearers, blooms can develop at sometimes widely varying times. This causes an uneven development of fruit across the tree. Be sure to wait until the fruit turns begins to turn yellow before harvest. That’s when it’s mature to eat! Fruit can be stored for up to a week in the fridge or can be juiced and stored in the freezer for later use.
Please contact your local county Extension office for more information. Happy Gardening!
Information for this article can be found in the UF/IFAS EDIS publication, “Key Lime Growing in the Florida Home Landscape” by Jonathan H. Crane: https://edis.ifas.ufl.edu/publication/CH092
UF/IFAS Extension is an Equal Opportunity Institution.
by Ray Bodrey | Apr 8, 2021
The Sunshine State produces a wide selection of citrus, with a number of varieties that can be grown right here, in your Panhandle dooryard. And, what is more satisfying than picking fresh fruit from your very own trees? So, are you looking for a different variety to plant? The ‘Parson Brown’ sweet orange may be of interest. It can certainly add uniqueness to your dooryard citrus grove.
Originating in China, orange varieties began being introduced in Europe in the fifteenth century. As for introduction to America, Columbus brought orange seeds to the new world on his second voyage in 1493. The first plantings in Florida were around 1513 in the settlement of St. Augustine. For the ‘Parson Brown’, a chance seedling originated at the home of Reverend N.L. Brown near Webster in 1856. Sumter and Seminole counties are still home to some of the largest densities of ‘Parson Brown’ orange trees in the state.
Figure 1: ‘Parson Brown’ Sweet Orange. Credit: D.P.H. Tucker, Ray Bodrey, UF/IFAS.
The Parson Brown, however, is often overlooked. The most popular dooryard sweet orange varieties grown throughout Florida are Navel, Hamlin, Valencia and Pineapple. Availability of this variety in our region is not easily found either, as you may have to search to find a tree.
Unlike the short, round appearance of many citrus trees, the Parson Brown tends to grow tall and slim. The Parson Brown’s more upright tree structure is very distinctive. A specimen will certainly stand out in a grove. The fruit and yield rival a Hamlin orange, particularly when grown in heavy, hammock soils rather than sandy soils with low organic content. The variety is also not as marketable as the Hamlin on a commercial level, due to the heavier seediness. You can expect at least 10 seeds per fruit. Average diameter of fruit is between 2 ½” to 2 ¾”. Harvest season for fruit is generally between October and January. Evidence suggests that along with the ‘Sugar Belle’ variety, the ‘Parson Brown’ may be more disease resistant, specifically more tolerant to citrus greening. HLB or citrus greening is a disease that has devastated both commercial production and dooryard citrus across the state.
Contact your local county extension office for more information. Also, for more information on growing citrus in Florida, see the UF/IFAS Extension EDIS publication, “Citrus Culture in the Home Landscape” by Robert E. Rouse and Mongi Zekri.
UF/IFAS Extension is an Equal Opportunity Institution.
by Mary Salinas | Apr 1, 2021
Citrus canker symptoms on twigs, leaves and fruit. Photo by Timothy Schubert, FDACS
Citrus canker was found for the first time in the Florida panhandle in Gulf Breeze in southern Santa Rosa County in November 2013. Since that time, citrus canker has spread widely in the Gulf Breeze area and just recently in 2020 was found in two locations in Panama City and Panama City Beach in Bay County.
Citrus canker is a serious bacterial disease that only infects citrus trees. It will not infect any other plant species nor is it a threat to human health. Severely affected trees experience substantial leaf loss and premature fruit drop and serve as a source for infecting nearby citrus. The disease spreads through wind, rain, and transportation of infected plant material from other locations.
This highly contagious disease has no cure although progression of the disease can be slowed through the use of copper-based products. This publication guides the homeowner on using copper.
Citrus canker lesions on leaves are raised, rough and visible on both sides of the leaf. Photo by Timothy Shubert, FDACS.
Not all citrus varieties are equally susceptible to this disease. Grapefruit, lemon, and lime are some of the most vulnerable while tangerine and tangelo varieties are among the most resistant.
What should you do if you suspect your citrus is infected with this disease?
- Look at this guide for more information and compare the symptoms on your tree to the photos. Lesions on the leaves penetrate through the leaf so they are visible on the upper and lower leaf surfaces, are rough, and have a yellow halo. The lesions look similar on the fruit and stems. Lesions (or cankers) on the stems usually indicate a longer standing infection of a year or more.
- Consult your local Horticulture Extension Agent to confirm the diagnosis and obtain more information and control/removal strategies.
- Proper removal of infected trees is recommended to prevent the spread of citrus canker but is not mandatory. The best way to dispose of infected trees is through cutting them down and burning them onsite; this ensures than none of the plant material leaves your yard to infect other areas. Consult your local burn regulations before burning. Stray leaves, branches and fruit should be raked and burned or double bagged for the trash. Please avoid disposing of any of your citrus trees by putting them by the side of the road for pickup by the county yard waste recycling or regular waste disposal. The bacterium will survive in the plant tissue and be spread to other neighborhoods in the county. You can, however, double bag infected plant material in sturdy bags and place it in the trash.
For more information please see:
UF IFAS Gardening Solutions: Citrus
Citrus Culture in the Home Landscape
UF IFAS Extension Online Guide to Citrus Diseases
by Danielle S. Williams | Mar 4, 2021
Shiranui mandarin
You’ve likely seen them in the grocery stores, and you’ll see them now through April. A large, lumpy (some may say ugly) piece of orange fruit with a bump near the stem. But what exactly is this special looking fruit? It’s a Shiranui mandarin!
The name ‘Shiranui’ is the generic term for this variety of citrus. You may have seen the same variety of mandarin marketed in grocery stores as ‘Sumo Citrus’ which is a trademarked name for the variety. In Japan, they are widely known as ‘Dekopons’. No matter what you call them, they are easily recognized by their distinctive appearance.
The Shiranui mandarin is a hybrid between a Ponkan tangerine and a Kiyomi Tangor (sweet orange x satsuma mandarin). They are easy to peel, sweet, and seedless. Shiranuis are considered to be one of the sweetest and most flavorful varieties of citrus on the market. The fruit are large and have a large protruding bump near the stem that resembles the top knot hairstyle of a Japanese sumo wrestler (hence the trademarked name ‘Sumo Citrus’).
While the majority of Shiranui mandarins on the market are grown in California, the variety can be grown here in Florida and several citrus growers in North Florida and South Georgia have began to experiment with plantings in the region. Homeowners, too, can try their hand at growing the variety as many Florida certified citrus nurseries carry the variety. For more information on different citrus varieties, contact your local UF/IFAS Extension Agent.
by Sheila Dunning | Dec 4, 2020
Frost on Dune Sunflower
Picture by: Pam Brown
UF/IFAS Extension
December is finally here and that means consistent nights of watching for dropping temperatures. Tropical plants and newly installed shrubs are susceptible to cold injury. Those colorful, blooming plants that have added a tropical look to the landscape all summer may begin to suffer when the temperatures drop below 500 F. Leaves may turn yellow and flowering stops. These plants will need to be moved inside or have temporary greenhouse built around them. But, hardy plants that haven’t established a sufficient root system will also need additional attention when the temperatures drop dramatically.
The ability of plants to endure a freeze depends on the species and the weather leading up to the extra cold night. Gradual decreases in temperatures helps plants acclimate to winter. But, a sudden one day drop of 40-50 degrees results in a rapid freeze that causes ice to form inside the plant cells. Leaf and stem tissue expands so quickly that it splits, resulting in parts of the plant incapable of transporting water and nutrients, as well as, performing photosynthesis. However, it may be late the following spring before the damage is noticed, when that section of the plant has slowly staved to death.
Cracked bark from frost
Additionally, plants can experience desiccation or drying out. This happens when dry winds and solar radiation result in the loss of more water from the leaves than can be transported by a cold root system. The resulting symptom is marginal and/or tip burning of leaves that leads to totally brown leaves.
Freezes (when the temperature drops to 320 F) are characterized as radiational or advective. Radiational freezes occur on calm, clear nights when heat radiates from the surfaces of plants, making them colder than the air due to the rapid loss of heat. If there is moisture in the air, ice will also form on the surfaces. Under these conditions, ice forms between plant cells, rather than within the individual cells. Most hardy plants can tolerate these type of freezes if they are properly hydrated.
Advective freezes occur when cold northern winds move in rapidly, dropping temperatures quickly, and causing widespread foliage desiccation. Cultivation and maintenance practices can impact a plant’s ability to endure extended periods of low temperatures. Shade-tolerant species installed under the canopy of a tree typically display less injury from radiational freezes because the trapped heat from the ground and the overhead foliage creates a microclimate. Well-watered soil around a plant will absorb solar radiation during the day and re-radiate heat over night, raising the temperature around the plants. Shrubs that are not pruned in the late summer or fall have leaves that can withstand frost and wind. But, the removal of foliage late in the growing season triggers a flush of new growth, that is very sensitive to lower temperatures. The same response can result from fertilizer applications after plant’s have slowed down in growth.
Irrigation Frost Protection on Citrus
Row Cover
Picture by: Univ of Maryland Extension
So, what can you do to prepare for upcoming freezing temperatures? Begin by avoiding pruning and fertilizing at the end of the season and making sure that the plants have been watered within 24 hours of a cold night. Next, insulate against water loss and increase heat radiation by adding a three-inch of mulch, as well as, covering the trunks of sensitive trees with a commercial tree wrap. Then, consider what needs to be covered. Frost cloth or other breathable fabrics can trap heat for the night and provide a protective layer from frost settling on the leaves. It needs to be placed by mid-afternoon and removed the next day when temperatures are above 320 F. Plastic is not recommended unless the timing regime can be followed reliably and a structure is used under the material to keep the plastic off the foliage. Anchoring of the cover is critically important in the event of an advective freeze.
Finally, turn off the sprinkler system. Commercial agriculture often uses a running irrigation system to keep the leaf surface temperatures near, but not below, 320 F because sprinkling utilizes latent heat released when water changes from a liquid to a solid state. The thin layer of ice melts and re-freezes on the surface throughout the night, without ice forming within the plant tissues. For the technique to work, sprinkling must begin as freezing temperatures are reached and continue until thawing is complete. Landscape systems are not designed to deliver the amount of water over the length of time required to accomplish this type of frost protection.
When the cold nights have passed, don’t forget to check your plants for water. But, wait until winter has passed before pruning out the frost damaged stems.
