Central - Winter 2020

Sara Shields, Singh, Raghuwinder, Strahan, Ronald E., Polozola, Michael, Carriere, Mark, Fontenot, Kathryn, Kirk-Ballard, Heather

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Greetings and Welcome to the Winter 2020 Edition of the Central Region Horticulture Hints!

While the weather during winter months typically limits gardening activities outside, this is a perfect time to explore the online resources provided on our new horticulture webpages on the Dean Lee Research and Extension Center website. The posted information covers commercial and home horticulture topics. The home horticulture section includes information applicable to all Louisiana residents within the LSU AgCenter Central Region. Updates and notes on our Louisiana Super Plants and native plant demonstration gardens are available, along with articles and resources on home fruit and vegetable production.

One of the newer features in the resources section of the Central Region Horticulture page includes information on backyard beekeeping. This page includes a plethora of information, from articles on honeybee removal and swarm collection, which is a popular topic each year, to multiple information sources on pollinator gardening. Video links cover topics on beekeeping basics, controlling mites in beehives and monitoring hive health. Additional resources include publications, the Beehive Buzz Blog and links to reputable resources from outside the LSU AgCenter.

The newest addition to the Central Region Horticulture page is information regarding the Louisiana Agriclimatic Information System (LAIS). Applicable information available on the LAIS site includes air temperatures, rainfall and chilling hours, which is of particular interest to individuals growing fruit trees. We hope you enjoy these winter months! If you have any gardening-related questions, please contact your local LSU AgCenter extension office.

Dr. Sara Shields
Louisiana Master Gardener State Coordinator
Central Region Horticulture Coordinator


Apple BlossomsjpgApple blossoms on young Dorsett Golden apple tree.
Photo by Sara Shields

Choosing and Caring for Your Poinsettias

The poinsettia (Euphorbia pulcherrima) is the traditional flower associated with Christmas and is the top-selling flowering potted plant in the United States. The brightly colored parts of the plant (called bracts) are actually modified leaves. The true flowers are the yellow beadlike structures in the center of the poinsettia. Poinsettias range in color from the traditional red to pink, white, salmon and bicolor.

When choosing a poinsettia, select plants that have brightly colored bracts and unopened or partially opened yellow flowers in the center and dark green foliage covering the stem to the soil line. Good form and size in proportion with the container is important. A good rule is the plant should be 2 ½ times taller than the diameter of the container. Check for evidence of insects, such as whiteflies, aphids or other pests, on the undersides of the leaves.

Once you have chosen your poinsettias for the season, a few simple steps can be taken to ensure it will endure the remainder of the holidays. Place the poinsettia in a bright location in the home where it can receive indirect light. Keep poinsettias away from drafts, HVAC vents and home heaters, and avoid letting the bracts touch cold windowpanes. Punch drainage holes in the bottom of the plastic decorator wrap or remove it for proper drainage and place the plant on a drainage saucer. Water the plants thoroughly when needed until the water drains out into the saucer. Then pour off excess water so the potting soil will not become soggy. Lastly, do not fertilize the poinsettia when the plant is in flower. With a few measures to ensure proper care, poinsettias may last many weeks or up to several months.

Mark Carriere
Agent, Agriculture and Natural Resources


PoinsettiasRBjpgA wide variety of poinsettia colors is available from retailers.
Photo by Rick Bogren, LSU AgCenter


Camellias Can Add Splash of Color to Winter Landscapes

Camellias come in many different colors, floral forms and mature architecture, but the two species most frequently planted in the South are japonica and sasanqua. Camellia japonica is the traditional choice for most established landscapes in the region. They have substantial flowers that can start blooming in October and continue into March depending on the cultivar selection. Preferring a shady location that provides their preferred light and soil acidity levels, japonicas can also thrive in a range of other locations. Be sure to note that planting in the dense shade or full sun may require extra care for the japonicas to be successful. In the open they will need more water to get established, and in a shadier understory more fertilizer may be beneficial.

Sasanquas have become popular in recent years. Compared to japonicas, they have a reputation for being hardier and are easier to get established in sunnier locations in the landscape. They tend to bloom earlier in the year within the window of October to January and like to flower all at once, while japonicas often pace their flowering.

Regarding basic care and use, camellias grow best with a soil pH of 4.5 to 6.5. Most fertilizers labeled for camellias and azaleas will help acidify the soil. It is always beneficial to perform an occasional soil test to make sure the area is not too acidic or basic. Camellias that have been in the same area for a long time may occasionally need micronutrients applied, especially iron.

The most common pest of camellias is tea scale on the underside of leaves and tends to get a foothold on heavily shaded and protected parts of a plant. A severe infestation will start to cause chlorotic spots on the upper portion of leaves as well. It can be treated by direct contact with horticultural oil when the temperatures are mild or with a systemic insecticide for most of the year.

Pruning will eventually be necessary for most selections. The best time to prune would be after flowering but before the first flush of new growth for the year. Sometime between March and April should be fine.

Both species work well as specimen landscape foundations or as a hedge. I tend to prefer sasanquas for a hedge since they are slightly more vigorous and respond very well to pruning. Japonicas are my favorite for a foundation planting as they have more variety in flower form and color combinations.

Dr. Michael Polozola
Assistant Extension Agent, Horticulture


Nuccios CarouseljpgA lovely bloom on Camellia japonica Nuccio’s Carousel.
Photo by Dr. Michael Polozola




Getting Crafty This Winter

Everyone has no doubt begun decorating for the holiday season. You’ve got your excited folks who started listening to Christmas music and threw up the decorations before the Thanksgiving holiday. (Hey, no judgment here.) Then you’ve got the folks like me who put the tree up the weekend after Thanksgiving. And some of us are busy and are just now getting around to it.

No matter what type of holiday decorating you do, there is one thing anyone can do very inexpensively by using what is just outside your door. You can create an evergreen wreath or swag with a few inexpensive floral materials and plant cuttings from the landscape.

The materials you will need to complete the project include fresh floral foam (3 inches by 4.25 inches by 3.25 inches) and a commercially made wire cage or one you create with a wire clothes hanger. You also need waterproof floral tape, 24-gauge wire (or similar) and 4-inch wire wood picks (optional). The tools you will need are pruning shears, wire cutters and a pocketknife or grafting knife.

Then you’ll need to gather an assortment of evergreen materials from the landscape. They could include cedar, camellia, evergreen wisteria, gardenia, holly, juniper, laurel bay, Leyland cypress, nandina, magnolia, mahonia, pine, pittosporum, sweet olive and wax myrtle. And don’t forget all the Christmas tree trimmings.

You also can go to a local nursery or box store selling fresh-cut Christmas trees and get the trimmings from such trees as blue spruce, Fraser fir, noble fir and Nordmann fir. They smell wonderful, and these plant materials offer several textures to incorporate into your wreath or swag.

Hollies such as American, Burford, English, Foster’s, Savannah, Winterberry and yaupon are excellent selections to help incorporate red berries. Another common landscape plant — nandina — also displays red berries in the wintertime.

If you use a commercially prepared cage of fresh floral foam, you can get started right away. However, you can make your own by securing a wire hanger around a cube of fresh floral foam. Add a water-impermeable material, such as contact paper, to the back of the foam to prevent water damage. Secure the backing and foam to the hanger using the waterproof tape in a tic-tac-toe pattern with two vertical lines and two horizontal lines encompassing the hanger and foam brick.

Hydrate the floral foam with water before beginning to add plant materials. This takes about 30 seconds. If you want your live cuttings to last longer, be sure to hydrate the foam several times a week. Next, begin placing greenery in the foam. You can use longer materials in the top and bottom for a swag or place the greenery equally in a circular pattern for a wreath look.

At this point make a fresh cut on the stem of the greenery itself by using a utility knife to create a sharp point. Cut down the bottom half of only one side of the stem as if to whittle away the bark. Now, stick this into the foam. Or you can wrap the wire on a 4-inch pick around the bottom half of the stem for stability and stick the stem and pick together into the foam.

Longer pieces such as fir, Leyland cypress and pine are great to use on the top and bottom of the swag. Then use more pieces to fill in both sides of the foam. This creates the skeleton, so to speak.

Then you may begin to fill in the piece with different textures, such as magnolia, camellia and holly. Finally, install the “centerpiece” — typically something with red berries, pinecones or a festive bow. You can secure the pinecones and bow using the wired picks or lengths of wire by wrapping and twisting the wire through the cones’ scales or around the center of the bow.

Create a swag by elongating the design, making the top and bottom longer and the sides of the piece shorter. For a wreath look, keep all the plant materials similar in length along all sides. You may use the hanger to hang on the door or the grommets or holes already in place on the commercial foam.

Voila! You have a DIY wreath that cost next to nothing. I’ve seen designs that retail for $50 to $100. Save that money to do some Christmas shopping or share with someone in need this holiday season. Merry decorating. It’s a fun activity for all!

Heather Kirk-Ballard
Consumer Horticulture Specialist

Evergreen Christmas Wreath DesignJPG



Start the New Year Off Right

All joking aside, 2020 has not been a grand year. There are things we can and cannot control, and we have to roll with life’s punches. Nevertheless, we can control many things in our garden. So, let’s make the most of December’s garden and start the new year off right by following best management practices to get the most out of our fruit and vegetable crops.

Cabbage 0462jpgA beautiful head of cabbage.

Monthly Garden Tips

December is the last month I think of as actual winter. January and February to me are very early spring. So, in this last month of winter here are a few to-do items to help keep the garden active!

December

  • Scout lettuce, strawberries and all cole crops for insects. Aphids, slugs, snails and worms tend to cause problems in the winter garden. Insecticides such as horticulture oil, insecticidal soap and Bifenthrin products (Ortho Bug –B-Gon Max) work great for aphid control. Insecticides that kill worms and loopers include Sevin, Bt (Dipel) and Spinosad. Snails and slugs are best controlled with baits. Iron phosphate baits are safest for pets. Early evening is when these pests feed. You want the baits to smell strong, so apply baits in the early evening for best results. If you have a lot of slug and snail problems remove mulch from around the base of plants. This gives them fewer hiding spaces.
  • Till and hip rows in the garden now for January-planted crops. Early January can be very wet.
  • Plant onion sets. Choose sets that are thin, the size of a pencil or thinner. Thicker plants tend to bolt in cold weather and set seed rather than forming bulbs.
  • Cover blooming strawberry plants when temperatures drop below 32 degrees Fahrenheit. Plants not in bloom? No need to cover.
  • Order spring vegetable seed now if you want first pick of the great varieties. Wait too long and other gardeners will order all the good varieties.

January

  • Onions can be planted from mid-December to early January. In early January, continue to plant onions sets. Bulbing onion varieties that perform well include but are not limited to Texas Grano, Mr. Buck, Texas 1015Y, Pinot Rouge, Red Burgundy and Miss Megan.
  • Mid-January through the end of February: Transplant broccoli, cabbage, cauliflower, chard, kale and lettuce into the garden. You can also direct-seed carrots, radishes, turnips and other rooting vegetable crops.
  • Mid-January through Mid-February: Plant Irish potatoes into the garden. Cut the potatoes a few days before planting. Cut larger potatoes in quarters and smaller potatoes in half. This larger size helps reduce rot. It doesn’t matter if the potato pieces face up, down or sideways. They will grow.
  • Vegetable growers in south Louisiana should start their tomato, eggplant and pepper transplants in mid-January. North Louisiana vegetable growers should wait until the end of January or the beginning of February. It takes between eight and 10 weeks to germinate and grow into a decent-sized tomato, pepper and eggplant seedling for the garden. Keep seedlings in a warm and bright area. One week prior to transplanting, move the seedlings outside to harden off.

February

  • Continue to transplant broccoli, cabbage, cauliflower, chard, kale and lettuce transplants into the garden. Successive planting (a portion of a row or a new row) every two weeks ensures a steady harvest.
  • Direct-seed beets, turnips, mustard, parsley, radishes, lettuce, snap beans and Irish potatoes.
  • Pull winter weeds. Hand pull or cultivate with a tiller or hoe. Get weeds out of the garden. Small insects like thrips like to hide here and get your spring crops later. Pre-emergent herbicides like Dual and Treflan are wonderful technologies that can make gardening especially in larger gardens easy. To control grasses in the garden use Poast or other herbicides with the active ingredient sethoxydim to kill grass, not broadleaf weeds.
  • Leave space for spring crops, which will go into the garden in March and April. If you have not pulled up rows, be sure to get it done at the first chance of dry weather. Spring is here!

Dr. Kathryn Fontenot
Vegetable Crops Specialist


Winter Turfgrass Management

The Dormant Season for Turfgrasses Begins in December

December begins a bleak time for warm-season turfgrasses. Most lawns should be dormant or at least close to this stage by Christmas. Because lawns are not actively growing, fertilizer applications are not needed during the winter. Actually, you should have stopped nitrogen fertilization on home lawns by late summer (late August to very early September for St. Augustine grass and centipedegrass).

Nitrogen fertilizer on dormant to semidormant St. Augustine grass, centipedegrass and zoysia grass lawns can lead to increased brown patch and winter kill. Also, nitrogen applications during this time have a greater potential for leaching or movement into nontarget areas.

Soil Sampling and pH Adjustments

Winter is an excellent time to collect soil samples and submit them for analysis. Samples should be a composite of soil collected from 3 to 4 inches deep at various places around the lawn. Mix well and reduce the sample to about 1 pint of soil and take it to the LSU AgCenter Extension Service office in your parish or to a participating garden center. Make sure to specify the type of grass you are growing on the soil test form.

Soil samples submitted to the LSU AgCenter result in a wealth of information concerning the overall fertility of your soil. If results of the soil test indicate the soil pH is too acidic, lime will be prescribed in the soil test recommendations. Sulfur may be prescribed for soils that are too alkaline. Winter is the best time to apply lime or sulfur so that it can be activated by for the growing season next spring and summer. The correct soil pH is extremely important and has everything to do with nutrient availability and fertilizer performance.

Turf Establishment

Postpone any permanent warm-season turfgrass seeding until next spring. Soil and air temperatures will be too cold for germination and growth.

Sod, such as St. Augustine grass and centipedegrass, can be laid during winter and established successfully during the spring. But remember to maintain good moisture to prevent the sod from dying. Establishment of sod is easiest, however, when sodding is delayed until the middle of spring, well after spring green-up.

Large Patch Disease

Large patch disease, which was once known as brown patch, can come and go throughout the winter if the weather is mild. Treatment with fungicides containing myclobutanil, propiconazole, pyraclostrobin, and triticonazole and azoxystrobin will reduce the spread of large patch. Damage from large patch will slow spring green-up, and diseased areas will remain unsightly until warmer spring weather conditions help with turfgrass recovery. These diseased areas are more prone to weed problems.

Winter Weed Management

Broadleaf weeds, such as clover and lawn burweed (sticker weed) and annual bluegrass infesting St. Augustine grass, centipedegrass and zoysia grass, and dormant bermudagrass, can be suppressed with a late fall application of atrazine herbicide followed by a winter application. The window for these atrazine applications is from November to early March. Herbicides containing a three-way mixture of 2,4-D; dicamba; and mecoprop (trimec-type herbicides) can be used for winter broadleaf control on the same lawns that were sprayed with atrazine. MSM (metsulfuron) works well on lawn burweed and is highly effective on clovers and false garlic. Weed-and-feed products can be substituted as your first application of fertilizer during the early spring.

When Should You Resume Fertilizing Your Lawn

Lawns may show signs of green-up in southern Louisiana in late February. Do not push turfgrass growth with fertilizer at that time! Fertilizer applied too early will feed winter weeds and will result in lush turfgrass growth that is more susceptible to injury from late frosts and increased levels of large patch disease. Lawns may be fertilized in the New Orleans area by late March, but delay fertilizing central Louisiana lawns until April. Consider fertilizing lawns in north Louisiana around mid-April.

Dr. Ron Strahan
Turfgrass Science and Weed Science Specialist

Mock strawberryJPGMock strawberry


wild geranium is a common winter broadleaf infesting  lawnsJPG

Wild geranium is a common winter broadleaf infesting lawns.


Lawn burweed germinates in lawns fall and produces painfull stickers in the springJPG

Lawn burweed germinates in the fall and produces painful stickers in the spring.


Catchweed bedstraw is a sticky winter weed that attaches to pants and petsJPG

Catchweed bedstraw is a sticky winter weed that attaches to pants and pets.



Checklist for December, January, February

December

  1. In the vegetable garden: Bunching green onions and shallots should be harvested by digging up the clumps. You may replant a smaller piece to continue producing. You can plant beets, Brussels sprouts, cabbage, carrots, celery, cabbage, leeks, lettuce, radishes, shallots, spinach, Swiss chard and turnips.
  2. In the lawn: This is a great time to sharpen mower blades and take care of any mower or weed trimmer maintenance before storing for the winter. Rake and keep fallen leaves of deciduous plants and trees to use as a mulch or to compost.
  3. In the landscape beds: Protect the roots and rhizomes of tropical plants by spreading a 4-6-inch layer of mulch around the base of the plant. Plant tulip and hyacinth bulbs at the end of the month.
  4. Trees and shrubs: Prune off freeze damage to tropical herbaceous foliage plants, such as gingers and philodendrons. Heavily mulch cold-sensitive trees and plants and cover them in extended periods of below-freezing weather.
  5. Fruits: Heavily mulch citrus trees to protect them from freezing temperatures. Cover young, tender citrus trees and utilize heat lamps during extended freezes.

January

  1. In the vegetable garden: End of January through early February is a good time to start tomato, pepper and eggplant seeds in sunny windows or indoors under grow lights, in hotbeds or in greenhouses.
  2. In the lawn: Give your spring lawn a leg up by treating weeds this month. If weeds are present, you can use liquid atrazine with the active ingredient 2-chloro-4 ethylamino-6-isopropylamine-s-triazinefor pre-emergence and early post-emergence on annual bluegrass weeds and many winter broadleaf weeds in your turfgrasses. Use in combination with 2, 4- D; mecoprop; dicamba; and carfentrazone for the best results. Follow product label for rates and use a spreader sticker.
  3. In the landscape beds: Apply mulch at a 2-inch depth to keep weeds in check. Pine straw, leaves and pine bark are all excellent choices. Trim freeze-damaged or dormant perennials back this month to keep a clean look to your landscape beds.
  4. Trees and shrubs: Winter is a great time to trim deciduous trees. Tree structure will be easier to see when selecting limbs to remove, and they will be lighter for disposal without the foliage.
  5. Fruit: Propagate dormant fig trees by hardwood or softwood cuttings this month. Take cuttings from the last one to two years’ growth at about one-half to three-quarters of an inch in diameter and 8-12 inches long and place cuttings in potting soil that is kept moist and warm. It is a good idea to place them in warm windows with bright light. Take several cuttings in improve success rate.

February

  1. In the vegetable garden: Plant cool season vegetables — beets, broccoli, cabbage, carrots, cauliflower, Swiss chard, collard greens, lettuce, mustard greens, potatoes, radishes, spinach, snow peas and turnips. Cut seed potatoes with a couple of eyes about the size of a golf ball and plant 4 inches deep and 12 inches apart.
  2. In the lawn: Perform lawn equipment maintenance this month. Shops will be less busy this time of year. Calibrate your broadcast spreader. Consult the Louisiana Home Lawn Series Pub. 3624-SSS for detailed instructions. Control weeds.
  3. In the landscape beds: Trim ground covers before new spring growth occurs. Prep beds for spring plantings by pulling weeds.
  4. Trees and shrubs: Bare-root roses should be planted no later than this month. Prune your roses on or around Valentine’s Day and begin a preventative spray program alternating fungicides for blackspot and powdery mildew. This is a good time to fertilize spring-blooming trees and shrubs.
  5. Fruit: Time to fertilize fruit trees and shrubs, including apples, peaches, citrus, figs, blueberries and blackberries. This is also a great time to plant pecan trees such as Elliot. Syrup Mill is an excellent pollinator for Elliot. McMillan, Gafford and Amling are recommended for home orchards; give 50 to 70 feet between trees.
Dr. Heather Kirk-Ballard
Consumer Horticulture Specialist

Armillaria Root Rot of Woody Ornamentals, Fruits and Trees

Many homeowner and commercial landscapers are noticing clusters of mushrooms appearing in their landscapes. These mushrooms are fruiting bodies of Armillaria root rot caused by Armillaria spp. It is a destructive disease of a wide variety of woody ornamentals, trees, shrubs and fruit trees. Common host plants include roses, camellias, azaleas, crape myrtles, bottle brush, jasmine (confederate), Chinese elms, oaks, pines, Leyland and Italian cypress, apples, peaches, pecans and others. The disease is generally attributed to Armillaria mellea; however, several different species of Armillaria are capable of causing root rot. In the southeastern United States, A. tabescens is primarily responsible for causing the disease.

Symptoms caused by this disease are similar to those caused by other root rot pathogens. Infected plants wilt, rapidly decline and eventually die. Leaves turn yellow and defoliate. In some host species, the entire foliage turns brown. A white fungal mycelium is usually present underneath the bark at the base of the stem and the roots, which can be easily seen by removing the bark. In severely infected shrubs or trees, the white mycelium extends into the crown region, and even a few feet up on the trunk. Clusters of honey-colored mushrooms commonly appear at the base of infected plants or around it in the fall.

Armillaria tabescens is a soil-borne fungal pathogen normally associated with hardwood forests. It may survive in the soil on infected roots for several years. Disease can be more problematic in urban landscapes that are created on previously wooded areas. The pathogen becomes active when roots from a new tree or shrub come in contact with old infected roots. The disease spreads from one plant to another through root-to-root contact or by the growth of the fungus through the soil by means of fungal structures called rhizomorphs.

There is no cure for this disease. Once a host plant is infected and the fungus is established, little can be done to save it. No chemicals are available to control this disease. However, there are culture management practices that may help to either avoid or reduce the impact of this disease. Start with disease-free healthy plants. Do not plant them too deep. Completely remove and discard plants suspected to be infected with A. tabescens. Careful removal of the stumps and roots along with significant amounts of soil from previously infected sites may help reduce the fungal inoculum. Avoid planting susceptible hosts in the same locations where infected plants were previously removed. Water thoroughly and deeply and as infrequently as possible without causing drought stress. Avoid continuous wetting of the base and crown region of the plants, which favors the growth of the fungal pathogen. Use of excessive mulch (mulch mounds) around the base of the plant should be avoided to keep the crown region dry. Follow a proper fertilization program.

Suspected host plants infected with A. tabescens can be submitted to the LSU AgCenter Plant Diagnostic Center for confirmation. For more information, please visit our website: www.lsuagcenter.com/plantdiagnostics.

Dr. Raj Singh
Plant Pathologist and Director of Plant Diagnostic Center


Figure 1JPG

Italian cypress showing browning of entire canopy as a result of root rot caused by Armillaria root rot.
Photo by Raj Singh, LSU AgCenter



Figure 2JPGBottle brush showing white fungal mycelium extended 2 feet up on the trunk.
Photo by Raj Singh, LSU AgCenter



Figure 3JPGCluster of honey-colored mushrooms produced by Armillaria sp.
Photo by Raj Singh, LSU AgCenter


11/4/2020 5:23:23 PM
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