Last week at the Panhandle Fruit and Vegetable Conference, Dr. Ali Sarkhosh presented on growing pomegranate in Florida. The pomegranate (Punica granatum) is native to central Asia. The fruit made its way to North America in the 16th century. Given their origin, it makes sense that fruit quality is best in regions with cool winters and hot, dry summers (Mediterranean climate). In the United States, the majority of pomegranates are grown in California. However, the University of Florida, with the help of Dr. Sarkhosh, is conducting research trials to find out which varieties do best in our state.
In the wild, pomegranate plants are dense, bushy shrubs growing between 6-12 feet tall with thorny branches. In the garden, they can be trained as small single trunk trees from 12-20 feet tall or as slightly shorter multi-trunk (3 to 5 trunks) trees. Pomegranate plants have beautiful flowers and can be utilized as ornamentals that also bear fruit. In fact, there are a number of varieties on the market for their aesthetics alone. Pomegranate leaves are glossy, dark green, and small. Blooms range from orange to red (about 2 inches in diameter) with crinkled petals and lots of stamens. The fruit can be yellow, deep red, or any color in between depending on variety. The fruit are round with a diameter from 2 to 5 inches.
Fruit, aril, and juice characteristics of four pomegranate cultivars grown in Florida; fruit harvested in August 2018. a) ‘Vkusnyi’, b) ‘Crab’, c) ‘Mack Glass’, d) ‘Ever Sweet’. Photo Credit: Ali Sarkhosh, University of Florida/IFAS
A common commercial variety, ‘Wonderful’, is widely grown in California but does not perform well in Florida’s hot and humid climate. Cultivars that have performed well in Florida include: ‘Vkusnyi’; ‘Crab’; ‘Mack Glass’; and ‘Ever Sweet’. Pomegranates are adapted to many soil types from sands to clays, however yields are lower on sandy soils and fruit color is poor on clay soils. They produce best on well-drained soils with a pH range from 5.5 to 7.0. The plants should be irrigated every 7 to 10 days if a significant rain event doesn’t occur. Flavor and fruit quality are increased when irrigation is gradually reduced during fruit maturation. Pomegranates are tolerant of some flooding, but sudden changes to irrigation amounts or timing may cause fruit to split.
Two pomegranate training systems: single trunk on the left and multi-trunk on the right. Photo Credit: Ali Sarkhosh, University of Florida/IFAS
Pomegranates establish best when planted in late winter or early spring (February – March). If you plan to grow them as a hedge (shrub form), space plants 6 to 9 feet apart to allow for suckers to fill the void between plants. If you plan to plant a single tree or a few trees then space the plants at least 15 feet apart. If a tree form is desired, then suckers will need to be removed frequently. Some fruit will need to be thinned each year to reduce the chances of branches breaking from heavy fruit weight.
Anthracnose caused by Colletotrichum sp. to pomegranate fruit. Photo Credit: Gary Vallad, University of Florida/IFAS
Anthracnose is the most common disease of pomegranates. Symptoms include small, circular, reddish-brown spots (0.25 inch diameter) on leaves, stems, flowers, and fruit. Copper fungicide applications can greatly reduce disease damage. Common insects include scales and mites. Sulfur dust can be used for mite control and horticultural oil can be used to control scales.
A couple weeks ago, I was on a site visit to check out some issues on Canary Island Date Palms. The account manager on the property requested a site visit because he thought the palms were infested with scale insects. He noticed the issue on a number of the properties he manages and he was concerned it was an epidemic. From a distance, lower fronds were yellowing from the outside in and the tips were necrotic. These are signs of potassium deficiency with possible magnesium deficiency mixed in.
Transitional leaf showing potassium deficiency (tip) and magnesium deficiency (base) symptoms. Photo Credit: T.K. Broschat, University of Florida/IFAS Extension
Nutrient deficiencies are slow to correct in palm trees. It’s much easier to prevent deficiencies from occurring by using a palm fertilizer that has the analysis 8N-2P2O5-12K2O+4Mg with micronutrients. Even if the palms are part of a landscape which includes turf and other plants that require additional nitrogen, it is best to use a palm fertilizer with the analysis previously listed over a radius at least 25 feet out from the palms. However, poor nutrition wasn’t the only problem with these palms.
Upon closer look, the leaflets were speckled with little bumps. Each bump had a little white tail. These are the fruiting structures of graphiola leaf spot also known as false smut.
Graphiola leaf spot (false smut) on a Canary Island Date Palm. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
Graphiola leaf spot is a fungal leaf disease caused by Graphiola phoenicis. Canary Island Date Palms are especially susceptible to this disease. Graphiola leaf spot is primarily an aesthetic issue and doesn’t cause much harm to the palms infected. In fact, the nutrient deficiencies observed in these palms are much more detrimental to their health.
Graphiola leaf spot affects the lower fronds first. If the diseased, lower fronds are not showing signs of nutrient deficiencies then they can be pruned off and removed from the site. All naturally fallen fronds should be removed from the site to reduce the likelihood of fungal spores being splashed onto the healthy, living fronds. A fungicide containing copper can be applied to help prevent the spread of the disease, but it will not cure the infected fronds. Palms can be a beautiful addition to the landscape and most diseases and abiotic disorders can be managed and prevented with proper pruning, correct fertilizer rates, and precise irrigation.
Damage caused by azalea lace bug, Stephanitis pyrioides (Scott), feeding. Photograph by James. L. Castner, University of Florida. Severely damaged leaves become heavily discolored and eventually dry or fall off. Symptoms may sometimes be confused with mite injury, but the presence of black varnish-like excrement, frequently with cast skins attached, suggest lace bug damage (Johnson and Lyon 1991).
You may be noticing the color disappearing from your azaleas right now. Do your azaleas look bleached out from a piercing-sucking insect. The culprit is probably azalea lace bug, Stephanitis pyrioides. This pest overwinters in eggs on the underside of infested leaves. Eggs hatch in late March and early April. The insect then passes through five nymphal instars before becoming an adult. It takes approximately one month for the insect to complete development from egg to adult and there are at least four generations per year. Valuable plants that are susceptible to lace bug damage should be inspected in the early spring for the presence of overwintering lace bug adults, eggs and newly-hatched nymphs. Inspect these plants every two weeks during the growing season for developing lace bug infestations.
Both adults and nymphs have piercing-sucking mouthparts and remove sap as they feed from the underside of the leaf. Lace bug damage to foliage detracts greatly from the plant’s beauty, reduces the plant’s ability to produce food, decreases plant vigor and causes the plant to be more susceptible to damage by other insects, diseases or unfavorable weather conditions. The azalea can become almost silver or bleached in appearance from the feeding lace bug damage.
However, lace bugs often go undetected until the infested plants show severe damage sometime into the summer. By then several generations of lace bugs have been weakening the plant. Inspecting early in the spring and simply washing them off the underside of the leaves can help to avoid damage later and the need for pesticides.
Adult lace bugs are flattened and rectangular in shape measuring 1/8 to 1/4 inch long. The area behind the head and the wing covers form a broadened, lace-like body covering. The wings are light amber to transparent in color. Lace bugs leave behind spiny black spots of frass (excrement).
Adult azalea lace bug, Stephanitis pyrioides (Scott), and excrement. Photograph by James. L. Castner, University of Florida.
Lace bug nymphs are flat and oval in shape with spines projecting from their bodies in all directions. A lace bug nymph goes through five growth stages (instars) before becoming an adult. At each stage the nymph sheds its skin (molts) and these old skins often remain attached to the lower surface of infested leaves.
Nymphs of the azalea lace bug, Stephanitis pyrioides (Scott), with several cast skins and excrement. Photograph by James. L. Castner, University of Florida.
Azalea lace bug eggs are football-shaped and are transparent to cream colored. Lace bug eggs are found on the lower leaf surface, usually alongside or inserted into a leaf vein. Adult females secrete a varnish-like substance over the eggs that hardens into a scab-like protective covering.
Other plant species, such as lantana and sycamore, may have similar symptoms. But, realize that lace bugs are host specific. They feed on their favorite plant and won’t go to another plant species. However, the life cycle is similar. Be sure to clean up all the damaged leaves. That’s where the eggs will remain for the winter. Start next spring egg-free.
For more information go to: http://entomology.ifas.ufl.edu/creatures/orn/shrubs/azalea_lace_bug.htm
Reddish, round spots are the first sign of Entomosporium Leaf Spot on Indian Hawthorn. Photo credit: Beth Bolles, UF IFAS Extension
Indian hawthorn (Rhaphiolepis spp.) is one of those great evergreen shrubs with such a reputation for hardiness that most folks tend to plant it and not worry about it. Indian hawthorn is not a Florida native, but is adapted to our weather conditions and is widely used in home landscapes throughout the Southeast.
However, it is important that homeowners and landscape managers pay attention to them, particularly during the warm, often wet weather growing season. During such conditions, the plant is vulnerable to Indian hawthorn leaf spot, caused by a fungus called Entomosporium mespili. Several years back, this fungus spread through the once-popular red-tip plant (Photinia fraser), to the extent that this species is now rarely used.
An Indian hawthorn plant heavily affected with leaf spot fungus can be covered with round circles on the green leaves, eventually leading to plant death. Photo credit: Carrie Stevenson, UF IFAS Extension
Symptoms of leaf spot fungi include small, circular red spots on young leaves, which then expand into larger patches. On older leaves, the spots are gray in the middle with red/maroon borders. Eventually, leaves can drop and entire plants may defoliate and die. The disease typically spreads through rainwater or overhead irrigation.
To manage the disease, it is best to create space between a sick plant and a healthy one to allow better air circulation. This will allow leaves to dry off after rainfall events and prevent expansion of spores. Be sure not to overwater, prune, or fertilize shrubs that show signs of the disease, as this encourages growth—the fungus thrives particularly well on young, vigorously growing leaves.
For leaf spot problems that become difficult to manage with just cultural practices, fungicides containing chlorothalonil, myclobutanil, or propiconazole may be used. Always follow label instructions when using chemical management and apply in the spring or fall. In addition, dead or dying plants should be removed and replaced with cultivars showing resistance to Entomosporium leaf spot, including Eleanor Tabor, Indian Princess, Gulf Green, Betsy, Blueberry Muffin, Georgia Petite, Olivia, and Snow White.
My obsession with plants started with the purchase of my first house in Waverly, Alabama in the late 90s. I bought a house with seven acres and of that about 1.5 acres was a fenced yard. The landscape was not very appealing, so I was on a mission to make it beautiful yet functional for my dogs. The only problem was, as a new homeowner, I had very little expendable income for my burgeoning plant habit. This dilemma forced me to be a resourceful gardener.
Shop the discount rack at garden centers
- Many retail garden centers (especially mixed use stores with limited plant space) will discount plants simply because they are no longer flowering. Plants look perfectly healthy but are just not considered “retail ready” anymore, so rather than hold them over until they bloom again and appeal to most shoppers the stores tend to mark them down.
- Plants are either growing or they are dead, so it is common to find some outgrowing their container and are getting “potbound” which means the root system is outgrowing the pot. Potbound plants are hard to keep watered without wilting and the solutions are to transition to a larger pot or plant in the ground. Most garden centers are not equipped to pot up overgrown plants to larger containers, so the easier solution is to sell them quickly. If you purchase a plant with circling roots be sure to trim the bottom and score (slice) the root ball to encourage roots to spread laterally.
- Avoid plants that appear diseased (leaf spots, brown stems, mushy parts, rotting odor) or have active feeding insect activity.
Compliment other gardeners’ plants
- When you get gardeners together, they inevitably start swapping plants. I really don’t have an explanation for this other that good old southern hospitality, but I’ve noticed over the years that when you express appreciation of plants to other people they tend to end up in your own yard. Ask if you can take a pinch (for cuttings) or offer to divide a clump of crowded perennials and you are on your way to a trunk full of plant babies.
- I can’t recommend this for multiple safety reasons, but I have been known to photographs plants in my travels then strike up a conversation with a homeowner who insisted I take one home.
Experiment with basic propagation techniques
- Grow flowers from seed. Either purchase seeds (usually under $2/pack) or collect seed heads from spent flowers in your own garden. After flowers fade, allow them to set seed then either crush and distribute in other parts of your garden or store in a cool, dry place until you can swap with friends.
- Division – clumping perennials such as daylilies, cast iron plant, iris or liriope can be dug up and cut into smaller pieces with a shovel or machete. You only need to be sure to have buds on top and roots on the bottom to make a new plant. Other plants create offshoots that can be removed from the parent plant. Examples of these are agave, cycads, and yucca.
- Cuttings – the list of plants that can be propagated from stem cuttings is endless but a few that are very easy are crape myrtle, hydrangea, and coleus.
- Patented plants can not be propagated.
For more information read Plant Propagation Techniques for the Florida Gardener or contact your local UF/IFAS Extension Office.
Everyone likes their privacy. Usually, a large eight-foot privacy fence is built for that reason. That option tends to be expensive. What is a different approach for a similar result? A natural wall!
One advantage of having a natural wall is that a homeowner has options when choosing plants. When it comes to choosing plants for a natural wall, the first thing to decide is if a wall needs to be year round or seasonal. Size would be the next factor to determine.
Japanese Cedar (Cryptomeria japonica) has the capability of growing 40 to 60 feet in height and 15 to 20 feet in width. There are some smaller varieties to pick from, but where is the fun in having a small wall?
Another plant option that would require pruning, but make an excellent natural wall is Japanese Yew (Podocarpus macrophyllus). This specimen will grow 30 to 40 feet tall and 20 to 25 feet in width if left unpruned, however, it is a slow grower. Yaupon Holly (Ilex vomitoria) comes in several selections of various sizes so the height range is 3 to 20 feet. The width range is 5 to 15 feet.
The Emerald Green Arborvitae is a fast grower that would be ideal for the homeowner who does not want a tall wall. It keeps a tight pyramid shape that will reach heights up 12 to 14 feet and needs 4 to 6 feet of space. Green Giant Arborvitae or Thuja Giant (Thuja standishii x plicata ‘Gre) is an excellent tree to pick for a natural wall. It has the capability to reach 50 to 60 feet in height and spreads out 12 to 20 feet at maturity. This arborvitae is considered to be a fast grower since it can increase more than 24” per year.
The larger selections of Loropetalum are other shrubs that homeowners have used to establish their privacy wall. One can expect a height up to 15 feet if left unpruned and pinkish to purple strap-like flowers, which makes for a great wall height.
‘Yoshino’ Japanese cryptomeria
Photo by Karen Russ, ©HGIC, Clemson Extension
A yaupon holly cultivar (Ilex vomitoria ‘Roundleaf’). John Ruter, University of Georgia, Bugwood.org Creative commons license.
Thuja plicata: Giant Arborvitae. Credit: Ed Gilman, UF/IFAS
Podocarpus macrophyllus or Japanese Yew. Credit: UF/IFAS
These plants are some of the selections homeowners may choose to start their natural walls. Given time, these shrubs will develop into a dense screen for the interruption of unwanted light or noise. To learn more about the aforementioned plant material, contact your local UF / IFAS extension agent.