About a year ago, one of my regular blog readers asked if magnolia trees (Magnolia grandiflora) had any particularly redeeming qualities. The one in her yard was constantly dropping leaves and seedpods, and she was tired of it. Little did she know, she had stepped into the domain of an absolute devotee of the magnolia tree. I told her that as a child of the Magnolia State (Mississippi) with the new magnolia-centered state flag flying from my front porch, it was my sworn duty to defend this magnificent symbol of southernness. Well, maybe I wasn’t so dramatic, but I definitely took on the challenge.
Magnolia trees produce large cones/seedpods that are filled with wildlife food. Photo credit: Carrie Stevenson, UF IFAS Extension
First, I do empathize with the constant leaf dropping. We have a large, beautiful magnolia tree in our front yard, and it drops its thick leaves year-round. We just rake them into a natural mulch pile around the base of the tree, though. As for the seedpods—those I have learned to be wary of. A couple of summers ago as I walked to my mailbox, I didn’t see one on the curb, then promptly rolled my ankle on it and landed face-first onto the road. After massive swelling and bruising on my foot, I finally went to a doctor to discover I’d managed to tear a tendon. So, tread carefully around the dropping seedpods!
The sturdy branches of our magnolia tree have supported a swing for over a decade. Photo credit: Carrie Stevenson, UF IFAS Extension
But aside from that, it’s all positives. A Southern magnolia is as sturdy a tree as you could hope for—it is consistently ranked as one of the most wind-resistant trees in the landscape. Their thick, dense, upright trunks and the overall pyramidal shape allows the wind to whip around them, rarely causing damage. In fact, the only damage we’ve had to our tree was when a weaker tree fell on our magnolia and knocked some branches off. Eighteen years after Hurricane Ivan, it’s filled in and you’d never know it lost branches. Ours was planted 50 years ago to celebrate the birth of the previous homeowners’ son, and has been a source of shade and relaxation (we have a great swing hanging from it) ever since.
The broad, open shape of the fragrant magnolia bloom co-evolved with its beetle pollinator millions of years ago, before bees existed! Photo credit: UF IFAS
Like many other trees, magnolias have medicinal uses. The bark of a related magnolia species has been used in traditional Asian medicine to treat “anxiety, asthma, depression, gastrointestinal disorders, headache, and more” and our North American varieties were once used as an antimalarial drug. Modern research has shown seed extracts are effective in maintaining sleep and body temperature, as a sedative, and in reducing the intensity of epileptic seizures. As always, never attempt to use a plant-based home remedy without consulting a physician!
To me, nothing quite says springtime like a magnolia blossom. As buds, they are thick and velvety, completely covering the trees with pops of bright white. Once they bloom, these large (up to 8” wide) saucer-shaped blossoms give off a lovely fragrance, attracting pollinators. Interestingly, magnolias are such an ancient species that they evolved (in the Cretaceous period) before flying insects like bees and butterflies existed. Therefore, magnolias are pollinated by flies and flightless beetles, which crawl from one flower to the other, relying on their sense of smell to guide them. Because beetles are chewers, the flowers and leaves co-evolved to be thicker and tougher to offset and survive the bugs’ messy eating habits. Once the flowers have gone, the fuzzy grenade-shaped cones/seedpods grow on the trees. After the seedpods fall, they open to reveal brilliant red seeds. These have significant wildlife value, as songbirds, squirrels, deer, wild turkey, and quail eat the seeds. This time of year, many people use the waxy, deep green leaves for seasonal décor—magnolia wreaths are quite popular, especially in the south. Many people make their own, but companies often sell them for hundreds of dollars apiece!
Magnolia macrophylla ssp. macrophylla (Bigleaf Magnolia) Photo credit Danny Schissler
In our area, the Southern magnolia is only one of several beautiful native specimens of the Magnolia genus. In freshwater wetlands, the slightly more petite sweet bay (Magnolia virginiana) is easily recognizable by the backs of its leaves, fluttering a silvery gray in the wind. One of my very favorite trees is the bigleaf magnolia (Magnolia macrophylla) which boasts mind-boggling leaves that can be over 2 feet long! In his travels throughout the United States in the late 18th century, explorer and naturalist William Bartram described the leaves as “an expanded umbrella, superbly crested with a silver plume.”
The sweetbay magnolia is easily recognizable by the silvery gray color on the backs of its leaves. Photo credit: Dan Gill/LSU AgCenter
Magnolias may be so common as to seem unremarkable to many, but they are a hardy group of trees who have survived on the planet since dinosaurs roamed the earth. And that’s about as redeeming a quality as you can get. To learn about other magnolia varieties that work well in our area, check out this publication from UF IFAS Gardening Solutions.
Did you know that Petunias repel asparagus beetle or that Marigolds planted among potatoes discourage Colorado Potato beetles? Are you aware that cabbage planted near lettuce has an adverse effect on the growth and flavor? In this article I would like to talk about one of my favorite topics, companion planting. Companion planting can be defined as the practice of planting two or more plant species close together to gain benefits either on growth, flavor or pest control. I would like to talk about the many benefits of companion planting in more detail.
Trap cropping: when a neighboring crop is selected to attract the pests and distract from the main crop. An example of this is planting collards to attract the diamond back moth from cabbage or planting dill with tomatoes because tomato horn worms prefer dill.
Nitrogen fixation: planting legumes such as beans and peas have a relationship with bacteria in the soil called Rhizobium. Legumes can convert it to a form that plants can use.
Biochemical Pest Suppression: Some plants can exude chemicals from roots or aerial parts that suppress or repel pest and protect the neighboring plants. An example of this is African Marigold release thiopene which acts as a nematode repellent.
Physical Spatial Interactions: Tall growing sun loving plants can share space with lower growing shade tolerate plants. This results in higher yields and has pest control benefits. One of the oldest examples of this is Three Sisters (corn, beans, and squash). Corn is planted for the pole beans to climb and provides a high canopy of foliage that can confuse squash borer and reduce damage. Beans are nitrogen fixing and corn requires a lot of nitrogen. Squash has broad spreading leaves that provide a living mulch and reduce weeds and hold moisture.
Beneficial Habitats: provide a desirable environment for beneficial insects such as lady beetles, lacewings, hover flies, mantids, non-insects such as spiders and predatory mites. Plants in the Umbel family (carrots, parsley, dill) are known for this as well as sweet alyssum.
Security through Diversity: More mixing of various crops and varieties equals a degree of security to the grower.
Some good examples of Companions are the following:
Broccoli: mint, dill, rosemary; aromatic herbs help repel pest Cabbage: mint, onion, oregano, dill, sage, clover, chamomile, nasturtium; Chamomile improves the growth and flavor and Nasturtiums offer caterpillars an alternate food source Carrots: English peas, lettuce, onion family, tomato; maximize space, provide shade and nitrogen fixer Peppers: tomato, beans, onion, geranium, petunia; Geranium repels Japanese beetles and petunias repel a variety of insects Spinach: strawberry, cauliflower, eggplant, radish; radish repels leaf miners Tomato: asparagus, carrot, parsley, basil, marigold, garlic; garlic repels red spider mites
Written by: Muhammad Adnan Shahid and Mujahid Hussain
What made this freeze event damaging?
The duration of temperatures below freezing determine the amount of damage to citrus plants. In January 2023 the temperature dropped down to 17 F and stayed at that temperature for a longer time than in recent years. Unlike 2022-23, during the winters of 2013-14, the recorded low temperature was 18 F for half an hour. Similarly, during 2014-15, the temperature touched 19 F and stayed only for 15 minutes. Except for these two winters, in the past 12 years, temperatures never dropped below 20 F. What made this freezing event of December 2022 devastating is the long freezing hours between 17-20 F for 11 hours and even more the temperature stayed for about an hour at 17 F (Fig. No.1).
Fig. No.1. Shows the temperatures (17-20 F) duration during the past winters of 2011-2023. The temperature data is retrieved from Florida Automated Weather Network, UF/IFAS Extension Service (https://fawn.ifas.ufl.edu/). During these years, according to this data, only in December 2022, the temperature fell to 17 F which caused severe damage to the citrus in North Florida.
Symptoms After Freeze
Early Symptoms
The duration of appearance of symptoms after freezing was different for different citrus varieties. Even within the same varieties, the age of the plant and the rootstock are also factors that determined the duration of the appearance of symptoms. For example, in the UF 950 rootstock evaluation block at North Florida Research and Education Center in Quincy, the symptoms appeared on young UF 950 plants on Sour orange rootstock after 24 hours and after three days the plant completely turned brown.
Fig. No. 2. Shows the effects of freezing on UF 950 on Sour orange rootstock after day 1 (a) and day 3 of freezing (b). The young plants completely turned brown after three days of freezing.
However, a few symptoms that appeared after about 24 hours of freezing were similar on all plants regardless of age, variety, and rootstock. These include the blackening of new leaves and branches, hardening and yellowing of leaves, and formation of greenish and brownish patches (Fig. No. 3). The leaves of old citrus trees also became curly, stunted, and yellow. During the freezing event, the fruits on the trees became hard due to the nucleation of water.
Fig No. 3. Symptoms after 24 hours of freezing.
Low temperatures below freezing point cause the formation of ice crystals inside the plant, particularly in leaf tissue, causing a damaging effect of cell walls, and leaves appeared water-soaked upon thawing when temperature rose above the freezing point (Fig. 4).
Fig 4: Water-soaked leaves due to the ice crystals formation and their thawing inside the tissues.
Late Symptoms
One week after freezing, leaves started curling – turning brown and dry. At this stage, both leaves and fruits dropped very quickly, within a week giving plants a bush like appearance (Fig. No. 5 and 6). The fruits that remained on the tree developed multiple symptoms depending on the varieties. Fruits of some varieties formed micro-pits on the peel, however, the fruits of other varieties showed patterns of bright orange and yellow colors (Fig. No. 6a). The rotting leaves and fruits also attracted ladybug beetles, consequently this increased populations of other insects in freeze damaged citrus groves. You should keep in mind that the fruits that have been harvested after freezing need extra care as these fruits are more prone attacked by rotting fungi.
Fig. No. 5. Late symptoms of freeze damage on citrus trees.
Fig. No. 6. Fruits turn black and fall from the tree after freezing.
Fig. No. 7. The freezing caused the fruit’s peel to form patterns of bright orange and light-yellow color on the fruits (a). The rotting of leaves and fruits produces an odor after freezing that attracts ladybug beetles (b).
Bark splitting or cracking is a late symptom of freeze damage. Bark splitting or cracking will mostly be seen on stem and branches directly exposed to the sun. Bark splitting starts when sun light increases the temperature on the surface of the bark during daytime, but temperature drops after sun set resulting in unequal shrinkage and contraction of bark and inner plant tissues (Fig 8). Dropping of leaves and fruits is a good indication of plant survival, but if leaves dry while attached and don’t drop then it’s the sign of severe damage to internal tissue with a low chance of plant recovery (Fig 9)
Figure 8. Bark splitting and cracking as a consequence of freeze damage.
Fig 9. Tree with dried leaves still on the branches – it is indication of sever freeze damage to internal tissues
Recovering Plant After Freeze Damage
The recovery of plants is entirely linked to the level of damage to the plant internal tissues during the freeze event. Freezing damage can exacerbate the plant’s health, thereby minimizing the recovery of the plant. However, plants can recover if the internal cells (cambium and xylem and phloem) are alive enough to regenerate the branches. After an extreme freeze event, like what happened in December 2022, some citrus plants will recover in spring due to the presence of living cells in the branches and stems, but if the internal transportation system is damaged, the plant again starts to die back for the next several months. You should not apply any recovery techniques immediately after the freeze event. The best strategy is to wait for the spring to see if plants are giving any indication of recovery and observe their growth at least till May-June.
Fertilization
It is true that after damage, plants require nutrients to regenerate and grow but the application of nutrients is critical as excessive fertilization can also increase the risk of damage. Do not apply any fertilizer until new growth starts in spring. Fertilizers should be applied frequently, but rates should be decided depending on the degree of damage. The plants that are severely damaged will not be able to produce fruits in the next season therefore, the rate of fertilizer should be lowered to promote a slow recovery, as the damaged plants will not be able to uptake all applied nutrients due to slow water flow caused by minimum transpiration rate in the absence of leaves. In this case, any excessive application of fertilizer can cause toxic effects that can further halt the recovery of plants. The application of micronutrients is also important for the recovery of plants.
Plant Protection
Care should be taken to protect the plants from pathogens, insects, and weeds to enhance recovery. Citrus plants regenerate in the spring and aphids and whiteflies like to attack the young leaves, branches, and shoots. Therefore, an effective plant protection plan should be devised that includes the application of insecticides and fungicides. In general, one to two applications of fungicide should be planned along with nutritional spray to prevent infection on new growth. Removal of all fruit from freeze damaged trees is also important for quick recovery (Fig 10)
Fig 10. Freeze damaged stems with living and non-living tissues. Stem with living tissues will recover easily as compared to those with dead tissues
Fig 11: Fruit are removed from freeze-damaged tree
Pruning
Pruning should be avoided because it is not clear how much damage has been done to the plant. Pruning should be delayed until spring or summer. Ideally, pruning should be done on living wood to make sure that all the damaged parts have been removed. If the citrus tree has been damaged below the rootstock/scion union, it is better to re-graft the new scion on the rootstock instead of pruning. Pruning of trees that have been damaged below the scion union will result in the generation of rootstock. Therefore, re-grafting the plant or replanting is the best option. The Fruit Physiology Lab at NFREC-Quincy is developing tissue imaging techniques for quick estimation of percentage of tissue damage in freeze affected citrus tree shoots and roots.
Irrigation
Irrigation after freeze damage should be reduced. Damaged plants do not uptake as much water as healthy plants, therefore, excessive water in roots can cause the nutrients to move away from the plants and even can cause suffocation for young emerging roots. It is not recommended to completely cut off the water supply, because this can further damage the plants.
Research
The Fruit Physiology Lab at NFREC-Quincy is developing tissue imaging techniques for quick estimation of percentage of tissue damage in freeze affected citrus tree shoots and roots. A series of preliminary studies on the use of growth hormones (brassinosteriods, abscisic acid and jasmonic acid) and nutrients (silicon, K and Zn) to improve the cold hardiness is in progress. Preliminary data indicates that the use of growth hormones and plant beneficial nutrients has the potential to reduce freeze damage (Fig 12), but more detailed research and validation in large scale field trials is required. Postdocs and graduate students in The Fruit Physiology Lab at NFREC-Quincy are fully engaged with different research projects to improve the cold hardiness in citrus by hormonal and nutritional therapies. Recently, the lab got a funding to study new scion and rootstock combinations with high cold tolerance.
Fig 12. Effect of Silicon on cold hardiness of citrus plants sprayed with 100ppm of silicon one week before exposed to freezing temperature (-6 C) in programed freezing chamber
Conclusion
Florida has faced record freezing this winter season with recent events that occurred in the last week of December 2022 causing severe damage to citrus trees in North Florida. Citrus growers in South Florida are already fighting with the HLB disease and freeze damage in the North has added to the damage to the citrus industry in Florida. Careful planning and proper care can help damaged citrus trees to recover and start fruiting again. Trees with little damage to their woody parts will recover soon and start fruiting in the next season. However, the trees with more damage to their woody parts will take two or more years to recover enough to start fruiting. Therefore, proper assessment of the damage is important and recovery strategies should be devised according to the degree of damage. Recent freeze events gave us a big message that microsprinklers are not enough freeze protection for established trees. There is also a need to identify growth hormones, nutrients, or combinations of which can improve the cold hardiness of upper plant parts. In addition, exact estimation of recent freeze damage won’t be accurate until April-June.
People love eating potatoes, and farmers love planting them. Traditionally, Valentine’s Day is a known date for planting potatoes. This tradition goes back generations. Potato planting time in North Florida is during the coldest months of January to February, although February 14th is a popular planting day. The taste and texture of homegrown potatoes are far superior to those of store-bought spuds! Garden potatoes also provide a bounty of nutrients. The potato (Solanum tuberosum) is a member of the nightshade family. This cool-weather vegetable typically yields bigger crops in the northern portion of the U.S., however potatoes can be grown as a winter crop in warmer climates.
Potato Varieties
The most popular and successful varieties grown in Florida are based on yield, disease resistance, quality, and adaptability to warm climates. These varieties are white-skinned potatoes ‘Yukon Gold,’ ‘Gold Rush,’ ‘LaChipper,’ and ‘Sebago’, and red-skinned varieties ‘Red Pontiac’, ‘Red LaSoda’, and ‘LaRouge.’ For russet varieties, home gardeners can select varieties that mature relatively early (100-115 days), such as ‘Russet Norkotah.’ Exotic potato varieties are fun and interesting to try since these varieties are hard to find in supermarkets. They are often smaller, taking less time to cook, but are also very colorful, which can increase the nutritional content. Potatoes with bright orange flesh have more carotenoids, and those with red pigments have more anthocyanins, both having health benefits. Other fun varieties include fingerling types and varieties with blue/purple flesh. The ‘All Blue’ potato has deep blue skin and flesh and produces blue flowers. Certified seed potatoes are ideal and can be found at your local feed store or garden center.
Credit: C. Christensen
Planting Prep: Before Planting
The seed potato needs to be cut into the size of an egg, with at least one eye per section. They must be dried in a cool, dark place for a few days. Plant the sections in a 4-6 inch deep trench that receives full sun, with the cut side down and sprouts facing up. Potato plants are heavy feeders and need nutrition through the growing season. To determine what kind and quantity of nutrients to apply to the soil, get the soil tested by a qualified laboratory. Contact your local Extension office for local fertilization recommendations. Apply a 10-0-10 fertilizer at 7.5 pounds per 100-foot row, both at planting and again 3-4 weeks later, by side-dressing fertilizer about 4-6 inches to either side of the plant.
Growing, Harvesting, Storage
Potatoes are ready to dig in about three months. Since potato tubers push up above the soil surface, the soil needs to be mounded around the stems as the plant grows. Tubers exposed to the sun turn green, making them inedible. Remove the tops 2-3 weeks before digging to “toughen the skin.” After harvesting, potatoes need to be kept in a cool (60-65 degrees F) dark place for 10-14 days to allow any damages to heal. Move them to a final storage location with high relative humidity, good aeration, and cool temperatures (38-40 degrees F). Washed tubers should be allowed to dry thoroughly before storing. Under proper conditions, potatoes can be stored for 3– 6 months or more.
Palms in North Florida suffered serious damage as a result of freezing weather in December 2022. As spring approaches, we will be looking to see if the palms will recover. Learn what to do now and what to expect from your palms with UF IFAS Extension Escambia County.
