Dan Devenport, Singh, Raghuwinder, Strahan, Ronald E., Gauthier, Stuart, Trahan, Savannah, Polozola, Michael, Fontenot, Kathryn, Kirk-Ballard, Heather
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In the past few weeks, I have received several phone calls from individuals claiming that they have the Asian giant hornets — “murder hornets,” as they are known — in their yards.
I quickly let them know, and I want you to know, that these insects have only been identified in the Pacific Northwest, mainly in the state of Washington and on Vancouver Island, Canada!
There is a size difference between the two insects that should be noted. Murder hornets are very large, between 1.5 to 2 inches long. The cicada killers are a little smaller, about 1.5 inches long. Visual marking on the upper abdomens of these insects are very useful in identifying the two. Cicada killers have yellow stripes across their abdomen that are jagged and yellow in color. Murder hornets have smooth, straight lines across their abdomen that are either orange or dark brown in color.
It is interesting to know that in 2020, entomologists in Washington State were able to tie a small tracking transmitter, using dental floss, to the body of one of these murder hornets and tracked it back to its hive in a hollowed tree. They were able to destroy the nest, hoping to eradicate these insects. In 2019, Canadian officials were able to eradicate another nest in a public park on Vancouver Island, British Columbia.
Cicada killers normally appear during the summer months of July and August but evidently appear in September as well based on the recent phone calls I’m receiving. These insects feed on cicadas and, if not provoked, are harmless. Cicada killers are beneficial and are predators of cicadas.
It appears the movement of murder hornets is slow, and they more than likely will never make it down to our area, but stranger things have happened. If you hear of someone thinking that they have seen one of these murder hornets, more than likely they have encountered a cicada killer. The marking on the abdomen is a good way to identify the insect if they can get that close to analyze. Samples can also be dropped off to my office, and I can send them to our entomologists in Baton Rouge for identification.
The holidays are right around the corner, and if you haven’t passed by dozens of poinsettias in stores yet then you will soon. It’s easy to throw caution to the wind and load your shopping cart up when you see all the beautiful shades of red, green and white. Remember, patience is a virtue, and taking time to properly inspect plants for damage or imperfections will prevent the disappointment of tossing out a spent plant before the season is over. Healthy poinsettias can last up to six weeks after purchase. However, if you like a challenge, it is possible to keep a poinsettia around to see next year’s holiday festivities!
When looking for the perfect poinsettia, it is important to familiarize yourself with a little plant anatomy. Unbeknownst to many, the large colored leaves on the top half of the plant are not flower petals but are called bracts. The flowers are the small yellow and green clusters in the center of the plant known as cyathia. Because the flowers are so small, the large, colorful bracts help in attracting pollinators. If purchasing a traditional red poinsettia, the lower green leaves should be large, dense and dark in color. Leaves should be attractive with no signs of wilting or curling. Bracts should also be large and robust. Depending on the shade of red (and if not marbled), coloring should be bright and uniform. Leaf drop can occur if bracts are sagging or discolored. Take a step back and look at the shape of the plant. The poinsettia should appear healthy and evenly balanced. Check the cyathia for size and appearance of pollen. If you want a poinsettia that will last a while, choose a plant with small, unopened, green cyathia. If the cyathia are plump and yellow and pollen is present, then the plant won’t last as long. While you’re inspecting the plant up close, carefully check underneath bracts and between leaves for insects.
Now that you’ve selected your poinsettia, it must be safely transported to your home or office. Poinsettias cannot handle temperatures below 50 degrees or excessive heat, so leaving them in the car while you finish your holiday shopping is not the best idea. Breakage of branches and leaves can be prevented by carefully storing a poinsettia in a sleeve or placing it in a secure location where it won’t fall over. When home, remove the sleeve and find a location with at least six hours of bright light. Some sources say indirect sunlight is best to prevent fading of color. Avoid over and underwatering. Severe leaf drop can occur if the soil gets too dry, while root rot is very common in overwatered plants. Only use room-temperature water and take plants out of the decorative wrapping to avoid oversaturation. The best method to determine when it’s time to water is by lightly probing the soil with a finger. If the soil is dry and crumbly, it’s definitely time to water. If the soil feels moist and firm, then you’re good to go.
Poinsettias are a true holiday staple. If traditional red, green or white isn’t your thing, then there are plenty of other cultivars to choose from. Bright pinks, speckled reds, marbled yellows and many more brilliantly colored poinsettias are now available to express your unique holiday style.
For more information on poinsettias and other winter ornamentals, contact your parish horticulture agent or visit the LSU AgCenter website.
Assistant Extension Agent
Have you gone out to see that there has been an overnight ruckus in your pecan orchard?
Have you been left with a bunch of rachis where there used to be leaflets?
Have you or your loved one ever experienced rapid pecan defoliation?
Unfortunately, there is no compensation from a class-action suit, so we can end this trope and ask some questions to get to the bottom of what may be the culprit in your orchard.
If it is earlier in the growing season, the most likely culprit is May and June beetles. I very seldom get calls from people experiencing damage from them in larger trees. They seem to prefer targeting young plantings. They can seriously impact orchard establishment if major defoliation occurs. They often must be combated annually due to environmental factors. In one situation a grower found that trees closer to an overnight light source were especially prone to the problem. One of the most effective treatments is imidacloprid. It has the added benefit of minimal impact on many beneficial insects as well.
If it is later in the growing season and progresses rapidly, you may have been visited by the dreaded walnut caterpillar. These are much different than the annoying but less devastating tent caterpillars. The walnut caterpillar is an insect pest that used to be isolated to the southwest portion of the state but has been slowly creeping eastward. In a very short time period large trees can be significantly defoliated. At the nursery I collaborate with, we have seen midsized containerized trees defoliated overnight. For a young orchard and those with spray equipment, there are several treatment options. Bt and Spinosad among many others should have some efficacy. For large homestead trees and those with no spray equipment, treatment options are limited. Another issue is timing. By the time you notice the damage, it may be too late and they have moved on. Most calls I get on this issue end up being diagnosed based on damage received with the caterpillars being long gone.
I have just briefly touched upon treatment options for both of these pests. If you are experiencing something similar to these descriptions in your orchard, contact me at 318-427-2669 and we can discuss it further. We can work on proper diagnosis and a treatment plan tailored to your orchard.
Michael Polozola, Ph.D.
State Pecan Specialist
Fertilizer prices in the past year have doubled, and many experts predict that these prices may persist through the spring growing season. It has never been a better time for growers to evaluate their home fertilizer practices and to assess if modifications or cuts can be made to spare the pocket without sacrificing production. Cost-cutting fertilizer tips include:
St. Martin Parish
Winter is a great time to get outside and get things done in the garden. We are very fortunate here in the South to have good weather during the winter months for gardening, and it is an excellent time to plant trees and shrubs in the landscape.
Although deciduous trees and shrubs are in their dormancy, roots are still actively growing. Planting during December, January and February provides plants with several months to develop a strong root system before they put out a new flush of leaves and flowers in spring.
The structure of trees and shrubs in our lawns and gardens is very apparent this time of year. Dead branches, low-hanging branches and branches that cross one another are visible now and should be removed. Take this opportunity to trim your trees and shrubs. Removal will be much easier without the additional weight of leaves.
As retail nurseries begin clearing out Christmas trees and merchandise, they will be bringing in a new stock of woody trees and shrubs. Tropical plants will be available later in the warmer season when they are less likely to be damage by colder temperatures.
The National Arbor Day Foundation has started the Time for Trees initiative to highlight how “trees clean our air, protect our drinking water, create healthy communities and feed the human soul.” Founded by J. Sterling Morton in 1872 in Nebraska City, Nebraska, where an estimated 1 million trees were planted, Arbor Day is celebrated every year. In 2021 it will be celebrated in most of the country on April 30. On this day, individuals are encouraged to plant trees.
Louisiana celebrates Arbor Day on the third Friday of January. The LSU AgCenter Botanic Gardens at Burden will hold its annual Arbor Day event on Jan. 23 from 9 a.m. to 1 p.m. Free and open to the public, this event will feature educational talks on native trees given by experts from the LSU AgCenter. You and your family can plant a tree while there and get GPS coordinates so you can come back and visit “your” tree and watch it grow for generations to come.
When deciding what trees and shrubs to purchase and plant, it is best to sit down and consider the year-round interest of those plants. A great design will have beauty and interest in each season. That can include evergreen plants, flowering plants and deciduous plants that have excellent fall foliage change.
Evergreen trees and shrubs provide year-round greenery and are popular in almost every landscape design. Some good, large evergreen trees include live oaks (Quercus virginiana), Southern magnolias (Magnolia grandiflora), Leyland cypress trees (Cupressus × leylandii) and American holly trees (Ilex opaca).
The Southern magnolia has fragrant white flowers in late spring to midsummer, and in winter the female American holly trees sport gorgeous red berries that attract birds and other wildlife.
Some medium-sized evergreen trees are the Southern wax myrtle (Morella cerifera), camphor tree (Cinnamomum camphora) and red bay (Persea borbonia).
You can choose from several small evergreen trees with many different functions. Some have flowers and put on a display in the late fall into early spring. These include the camellia (Camellia japonica) and camellia sasanqua (Camellia sasanqua).
Other fragrant flowering trees include loquat (Eriobotyra japonica), banana shrub (Michelia figo) and sweet olive (Osmanthus fragrans). Other trees — including the Burford Chinese holly (Ilex cornuta ‘Burfordii’), yaupon holly (Ilex vomitoria) and eastern red cedar (Juniperus virginiana) — provide ecosystem services such as wildlife food.
Compared to evergreen trees, deciduous tree have a much larger selection for use in Louisiana. Some large deciduous trees with good fall foliage change that are also great as shade trees for the landscape are American beech (Fagus gramdifolia), bald cypress (Taxodium distichum), basswood (Tilia americana), pecan (Carya illionensis), tulip tree (Liriodendron tulipifera), sycamore (Platanus occidentalis) and cucumber magnolia (Magnolia acuminate).
Some outstanding small, spring-flowering deciduous trees are the fringe tree (Chionanthus virginicus), flowering dogwood (Cornus florida), Taiwan cherry (Prunus campanulata), saucer magnolia (Magnolia X soulangiana), parsley hawthorn (Crataegus marshallii), redbud (Cercis Canadensis) and silverbell (Halesia diptera).
Other deciduous trees with outstanding fall foliage change are the American hornbeam or ironwood (Carpinus caroliana), hop-hornbeam (Ostraya virginiana), swamp red maple (Acer rubrum Drummondii), Japanese maple (Acer palmatum), southern sugar maple (Acer barbatum), green ash (Fraxinus pennsylvanica), sweetgum (Liquidambar styraciflua), Chinese pistache (Pistacia chinensis) and many oak species, such as shumard oak (Quercus shumardii), nuttall oak (Quercus nuttallii), white oak (Quercus alba) and post oak (Quercus stellata).
Planting trees is a great way to leave a lasting legacy for generations to come to enjoy. In my humble opinion, trees are the key to combating climate change by conserving energy, sequestering carbon and reducing the overall concentration of greenhouse gases in the atmosphere.
Consider this proverb: “The best time to plant a tree was 20 years ago. The second-best time is now.”
Heather Kirk-Ballard, Ph.D.
Consumer Horticulture Specialist
Heather Kirk-Ballard, Ph.D.
Consumer Horticulture Specialist
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 veg crops.
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!
Kathryn “Kiki” Fontenot, Ph.D.
LSU AgCenter School of Plant, Environmental and Soil Sciences
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. Most lawn fertilization for growth should have stopped on home lawns by late summer (late August to very early September for St. Augustinegrass and centipedegrass).
Nitrogen fertilizer on dormant to semidormant St. Augustinegrass, centipedegrass and zoysiagrass 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.
I’m a big believer in soil testing. If your lawn did not perform well last growing season or you just want to get a quick check on soil pH, get the soil tested. 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 a 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. Augustinegrass 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 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 become more prone to weed infestations.
Broadleaf weeds, such as clover and lawn burweed (sticker weed) and annual bluegrass infesting St. Augustinegrass, centipedegrass and zoysiagrass and dormant bermudagrass, can be suppressed with a late fall followed by a winter application of atrazine herbicide. The window for these atrazine applications is from October to early March. Herbicides containing a three-way mixture of 2,4-D plus dicamba plus 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 it comes to managing lawn burweed specifically, don’t wait until the stickers show up in April to treat. It’s too late then. Spray burweed in early November with products mentioned previously. Repeat these applications in February and March.
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.
Ron Strahan, Ph.D.
Turfgrass and Weed Science
Sooty molds are a result of nonplant pathogenic fungi that grow superficially as a thin black layer on leaves, fruit, twigs and stems of various crop plants or trees. The fungi grow on the honeydew produced by insects with piercing-sucking mouthparts. The insects, including aphids, leafhoppers, mealy bugs, psyllids, scale insects and whiteflies, pierce the plant tissue with their stylets and feed on plant sap. While continuously feeding, these insects ingest a large volume of sap fluid into their bodies, which is not entirely digested. After extracting nutrients from the sap, these insects excrete excess water and sugars from their bodies in the form of a sticky, sugary substance called honeydew. Most of the time, these insects feed on young, tender new growth and the honeydew drops below on all plant parts, including leaves, fruit, twigs and stems. Additionally, the honeydew covers understory vegetation, concrete surfaces, sidewalks, furniture, parking lots, etc., under host plants infested by sap-sucking insects.
Sooty molds are saprophytic fungi with dark, powderlike spores that break down honeydew. Abundance of sooty molds lead to formation of a thin, black layer. There are several species of sooty molds, but the most common ones are Capnodium spp. and Fumago spp. Sooty molds do not directly affect the host plant on which they reside but can inhibit the photosynthetic ability of the plant by covering leaves, twigs, fruit and stems. Under extreme conditions plants entirely covered with sooty mold may lose vigor and be predisposed to other plant pathogens. Plant growth may also be retarded, and yields can be significantly reduced. The aesthetic value of the plants covered with sooty mold is greatly reduced.
All plant species that are hosts for sap-sucking insects with the piercing and sucking type of feeding are affected with sooty molds. Some of the common landscape plants heavily affected by sooty mold are azaleas, camellias, citrus, crape myrtles, magnolias, oleander, pears, pine, roses, sago palms and viburnum. Hedges, small bushes or other plants, such as boxwoods, Indian hawthorn and ground covers, get sooty mold if the trees under which they are planted are infested with these insects. This happens when the honeydew from insects high in the canopy of trees drops on the vegetation underneath.
Managing sooty molds is very simple. Keep insects, such as aphids, mealy bugs, scale insects and whiteflies, in check. Once the insect problem is solved there will be no new sooty mold occurrence. The existing sooty mold infestation dries out after some time and easily sloughs off the infested areas.
Pressurized water can be used to wash off the sooty molds. Care should be taken while using pressurized water because it may damage the plant parts.
Insect infestations are generally controlled with insecticides, insecticidal soaps or horticultural oils. Before applying any kind of chemical pesticide, it is very important to identify the insect properly. Samples of plants infested with insect pests may be taken to your extension agent for identification. Consult with your local extension agent on the use of chemicals for managing insects. The LSU AgCenter Plant Diagnostic Center is also available to diagnose your plant health problems.
Raghuwinder (Raj) Singh, Ph.D.
Horticulture Pathology Extension Specialist