Marcie Mathews, Singh, Raghuwinder, Strahan, Ronald E., Pinnell-Alison, Carol L., Fontenot, Kathryn, Kirk-Ballard, Heather
Get Your Soil Tested!
2021 Get It Growing Calendar
Order your calendar today!
Never miss an issue of Horticulture Hints from the LSU AgCenter!
Visit the Horticulture Hints website at
Then click on the Subscribe button!
If you’re like me, summer bloomers like marigolds, zinnias, periwinkles and lantana are left to bloom until the first killing frost burns them down, which is usually between Halloween and Thanksgiving. These and other summer favorites seem to catch a second wind in fall; their colors intensify as temperatures become milder.
By now, most gardeners have long since removed summer annuals and replaced them with fall/winter bedding plants like pansies, snapdragons and dianthus. But, even after our first frost, there is plenty of time to plant these and other fall flowers. Even a light frost or freeze will let you know which plants need cutting back or removing and which are frost-tolerant.
Here are some post-frost or post-freeze flower bed tasks:
Incorporate compost into the soil, apply a slow-release fertilizer, put down a fresh layer of mulch and enjoy a beautiful winter flower bed all the way until spring.
Research Associate, Northeast Research Station
A fresh layer of mulch will protect these petunias all winter.
Pecans are wonderful native trees for the landscape, providing shade, wildlife habitat and nuts for the homeowner. The pecan harvest has wrapped up for the year, and winter is the perfect time to assess the overall health of your pecan trees. Whether you have one tree, a few trees or an entire orchard, there are a few management practices that can be completed now to help improve the next year’s crop. First, because we did have several wind events that could have damaged limbs or left limbs hanging, survey your trees for broken limbs and prune them out if possible. Raking up and removing diseased nuts from around trees can help reduce disease inocula. Winter is a great time to take soil samples if this has not been done within the last three years. Proper fertilization and irrigation are two management practices that improve pecan tree health and production. Pecan trees are fertilized during the late dormant season of February or early March. Irrigation typically is not required during winter but will be necessary during dry periods in spring. Proper irrigation will help with tree health and pecan nut quality. The LSU AgCenter’s publication Homeowner’s Guide for Fertilizing Pecan Trees in Louisiana (Pub. 2075) can be found on our website.
Winter is the perfect time to plant pecan trees, too! Remember, pecan trees produce better quality and a higher quantity of nuts with cross-pollination. Select at least two varieties to plant that will cross-pollinate with each other if other pecan trees are not within a one-quarter mile radius. Purchase trees that are 4-5 feet in height. Larger trees usually suffer from transplanting shock. Trees grown in containers versus bare-rooted trees tend to survive better. Dig the hole larger than the spread of the roots. Prune any damaged roots and cut the taproot if it is circling the bottom of the container. Plant the same depth as grown previously.
Water well at planting and weekly thereafter for the first year. Do not overwater on heavy clay soils. Continue to water during dry periods the second year. Do not fertilize the first year since this may cause root burn. Use mulch at a depth of a few inches to help with weed control, prevent string trimmer damage to the trunk, and help moisture retention around the tree. Do not pile mulch up against the trunk of the tree. The LSU AgCenter’s publication Selection and Care of Pecan Varieties for Louisiana Yards (Pub. 2074) is a good reference.
Pest problems can be a challenge for the home pecan grower. Spraying pecan trees for insect and disease control is usually not economically feasible for the homeowner with just a few trees. Getting spray coverage up into the canopy of mature trees requires specialized equipment. Selecting pecan varieties with disease resistance is the best choice.
Pecan pests we receive questions about every year include pecan scab, aphids, stink bugs, fall webworm and pecan phylloxera. Pecan scab is caused by a fungus (Cladosporium caryigenum) and is considered the most destructive disease of pecan trees. Planting a resistant variety is highly recommended. Disease severity is dependent on rain frequency and the time of day rainfall occurs. Late afternoon and early evening rains may cause trees to stay wet all night, making them more susceptible to scab infection.
There are numerous aphid species that attack many plants. Aphids pierce the vascular tissue of the plant they are colonizing and suck the sap out of the tree. They typically feed on the undersides of leaves. While feeding on sap, they excrete a sugary liquid called honeydew. This is the sticky substance that collects on surfaces under infested trees. Pecan phylloxera is a gall-forming, small aphidlike insect (Phylloxera devastatrix). Mid-April is usually when the characteristic, knotlike galls appear on pecan trees. Infestations of this insect do not occur every year, and some pecan cultivars are not susceptible to an attack. Severe infestations can lead to deformed shoots and twigs, shoot dieback and deformed nuts that prematurely drop from the tree. If phylloxerae are present, one insecticide application can be made between the stages of bud development and early leaf expansion. However, the insecticide needs to be applied before you see galls. There are several scouting methods to determine if phylloxerae are present. Refer to the LSU AgCenter publication BUG BIZ: Pecan Phylloxera (Pub. 2547).
Stink bugs are difficult to control in pecans. They are very mobile and move in and out of trees. They have a large host range with any plant that forms a fruit or nut. They are feeding on the seed. They usually infest pecans late because a pecan tree is one of the last plants to still have a nut (seed) on the tree. Stink bugs have a piercing sucking mouth part. They inject a chemical in the nut that breaks down the tissue so they can suck out the material. The spotting on the flesh of a pecan caused by a stink bug can be confused with the spotting caused by scab. The flesh of a pecan with stink bug damage will have a bitter taste. Fall webworms form the large webs in several trees in the South, pecans, hickory, persimmon and sweetgum. The larvae (caterpillars) cause the damage by feeding on the leaves. They do not feed on the nuts and will not kill the tree. Defoliation of a tree can reduce the quality of the nuts, and severe defoliation can reduce the crop the next year. The web contains the feeding larvae. The web enlarges as the larvae move to consume more leaf material. Homeowners can reduce defoliation by pruning out as many webs as possible when they are small.
In summary, selecting disease and pest-resistant pecan varieties for planting, correct fertilization, mulching and watering during dry periods are very important to a homeowner’s success with pecans.
County Agent, Caldwell, Catahoula, Concordia, Franklin, and Richland Parishes
Pecan scab on nuts
Pecan phylloxera is a gall-forming small aphid-like insect. Symptoms appear in spring.
Webworms can quickly defoliate a pecan tree, causing unsightly damage.
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!
Consumer Horticulture Specialist
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.
A beautiful head of cabbage.
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!
Dr. Kathryn Fontenot
Vegetable Crops Specialist
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.
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.
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, 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.
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.
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
Wild geranium is a common winter broadleaf infesting lawns.
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 pets.
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
Italian cypress showing browning of entire canopy as a result of root rot caused by Armillaria root rot.
Photo by Raj Singh, LSU AgCenter
Bottle brush showing white fungal mycelium extended 2 feet up on the trunk.
Photo by Raj Singh, LSU AgCenter
Cluster of honey-colored mushrooms produced by Armillaria sp.
Photo by Raj Singh, LSU AgCenter