Central - Winter 2021

Sara Shields, Singh, Raghuwinder, Strahan, Ronald E., Fontenot, Kathryn, Kirk-Ballard, Heather

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3 rounded mounds of winter annual plantings. Two have purple flowers and one has yellow flowers. Plants are surrounded by pine straw.
Three Sorbet viola plants in Louisiana Super Plant demonstration garden.Photo by Sara Shields

Greetings and welcome to the winter 2021 edition of the Central Region Horticulture Hints!


You may have noticed some recent changes to our demonstration gardens as a result of the drainage project in and around the LSU-Alexandria campus. In an effort to re-establish the Louisiana Super Plant demonstration garden out front, we replanted from the Sorbet series of violas, one of our “go-to” cool-season annuals. Sorbet violas were added to the Louisiana Super Plant list in 2012 and have continued to perform wonderfully every year we have planted them in the demonstration gardens. The violas grow 6 to 8 inches high and about 1 foot wide and should be spaced about 10 to 12 inches apart. Best planted in full sun, these members of the violet family can be planted any time from fall through early spring and will continue growing into late April or early May and possibly later if we have a milder start to the summer months. Be sure to fertilize at planting and irrigate during times we are not receiving regular rainfall. With a little planning and care, these Sorbet violas can provide a nice pop of color in your landscape beds, containers or hanging baskets.

We hope you enjoy these winter months! If you have any gardening-related questions, please contact your local LSU AgCenter extension office.

Sara Shields, Ph.D.
Louisiana Master Gardener State Coordinator
Central Region Horticulture Coordinator

A mature oak tree before leaf fall in the autumn season. The tree has dark colored bark with several areas of light colored bark.
Water oak in landscape showing signs of decline. Photo by Sara Shields

Water Oak Warning


When I was starting out in professional forestry, I was a service forester in an urbanizing county in Virginia. One of the questions I frequently encountered was “What is the fastest growing tree for my landscape?” While this is still a common question, we generally recommend folks avoid planting fast-growing trees because they are more likely to be short lived and become maintenance headaches. In essence, fast-growing trees tend to have weak wood, so broken branches and tops would require heavy cleanup.

I still receive that question quite often in my capacity as county agent in Beauregard Parish. One tree that folks often inquire about is the water oak. The best description I have of water oaks is to think of them as the “teenagers of oaks” in that they have “issues.” According to Debbie Shaughnessy and Bob Polomski, of Clemson Cooperative Extension, water oaks have these problems:

  • They are more weak wooded than most oaks and prone to damage from wind, snow and ice.
  • They do not resist decay well.
  • Water oak trunks often rot by the time they are 50 years old.
  • Their shallow, spreading root systems compete for water and nutrients in the soil.
  • In warmer climates their leaves drop all winter, making raking a constant task.

I can affirm the observations of Shaughnessy and Polomski by virtue of site visits with homeowners. While water oaks can be good shade trees for the first 30 or 40 years, large water oaks tend to have broken branches and obvious cavities. When these compromised trees are near homes, improvements and parking areas, I consider them to be hazard trees and recommend their removal.

If you have a younger water oak, enjoy it while it is healthy and robust. Preventative pruning, such as training to a central trunk, keeping the main branches spaced at least 2 feet apart and avoiding making large pruning cuts, can help maintain the health of younger water oaks. However, as a water oak ages, keep an eye on it for damage, which will likely be a site for decay. If you have concerns about your water oak, contact your extension agent or extension forester and ask for a site visit to see if your aged water oak is becoming a hazard to your home.

Keith Hawkins
Associate Extension Agent

Pruning Fruit Trees


Like most trees and shrubs in the landscape, pruning fruit trees should occur when the plants are dormant. While pruning fruit trees in the middle of January is not a suggested practice, early to mid-February is recommended for several reasons. For one, the average last frost date in this part of Louisiana is March 15, so waiting until February to start pruning decreases the chance for damage from a late frost. It is also best to wait and prune at a time when the tree can heal pruning injuries and not be so stressed. Pruning too early might encourage growth, especially if temperatures fluctuate significantly. This tender new growth could be severely damaged if we happen to get a late frost.

For young trees, it is typically better to wait until late February or early March, which gives the trees a chance to break bud. Pruning after the trees have broken bud will allow you to go through and assess which limbs are dead, diseased, decayed or otherwise damaged. Additionally, pruning fruit trees also eases harvesting by shaping and reducing tree height. Pruning will also increase flower production on trees that bloom on new growth, such as peaches. Proper pruning will also allow for more light to reach the fruit, in turn improving fruit color. Thinning the fruit crop later in the season will further improve the fruit quality by improving fruit size and sugar content.

It is important to follow proper pruning techniques when pruning fruit trees because different methods of pruning are used on different fruit species. The first step is to remove those dead, diseased, decayed and damaged limbs mentioned above. The branches should be cut back to a fork or bud, but be careful not to cut the branch collar, which is a ridge or area of wrinkled wood found around the base of the branch. The branch collar serves to heal nearby wounds, in which it quickly grows over the cut surface. You should not leave a stub sticking out of the collar because the collar will not be able to grow over the cut surface.

The next step is to remove the branches that grow toward the center of the tree. Branches crossing nearby limbs could cause rubbing injuries and should be removed. Additionally, removing these center branches will increase light penetration and air circulation to the center of the tree canopy. If there are any limbs of equal size that form a sharp “V” shape, one of the limbs should be removed before the limbs get very large to prevent splitting. Limb growth can be directed by pruning back to a bud or shoot that is pointing toward the direction where growth is desired.

Knowing the pruning process can help you assess each individual tree beforehand to decide which limbs need to be removed on each tree. The LSU AgCenter has informative publications on the issue. They are available both online and in your local LSU AgCenter extension office.

Sara Shields, Ph.D.
Louisiana Master Gardener State Coordinator
Central Region Horticulture Coordinator

A close up of light colored pink flowers belonging to a peach tree. The bark is a light brown color and the branch with the flowers is thin. There are other flowers on the tree but they are the focus of the picture.
Peach tree in bloom. Photo by Sara Shields

Plant Trees and Shrubs During Cold Months


A tree with low hanging branches with plenty of small red berries of the holly tree. Several birds are perched on the branches eating the berries.
American robin on a native holly. Photo by Norman Winter

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).

A close up of a cluster of white flowers. There are several unopened buds with a light brown fuzzy covering over the buds. A bee is in the lower right hand corner of the picture nectaring the flower.
Loquats are great evergreen trees with sweetly scented flowers in late autumn.

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).

Picture of a mature tree with a rounded canopy. The picture was taken in the fall and the tree is covered in bright orange fall foliage.
Chinese pistache is an excellent medium sized decidous tree for excellent fall foliage.

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

Checklist for December, January and February


December

  1. In the vegetable garden: Plant onions sets, such as leeks and shallots, this month. Harvest bunching onions. Store vegetable seeds in the refrigerator to keep them viable (able to germinate). Store in tightly fitted plastic or glass containers.
  2. In the lawn: Soil tests should be conducted every so often to check soil nutrient levels. If your soil tests indicate the need for lime, this is a good time of year to add it.
  3. In the landscape beds: Keep winter weeds out of beds. Transplant alyssum, columbine, daffodil, dianthus, foxglove, hollyhock, larkspur, lobelia, narcissus, pansy, snapdragons and sweet William this month. Protect the roots and rhizomes of tropical plants by spreading a 4-to-6-inch layer of mulch around the base of the plant.
  4. Trees and shrubs: Heavily mulch cold-sensitive trees and plants and cover them in extended periods of below-freezing weather. Winter is a good time to plant trees and shrubs. Water-in newly planted trees, but established trees will not need to be watered this month.
  5. Fruits: Heavily mulch citrus trees to protect them from freezing temperatures. Cover young, tender citrus trees by constructing a simple frame extending above the leaves and cover with clear plastic. Make sure the cover does not touch tender leaves, and place the cover during the day to trap radiant heat coming up from the ground.

January

  1. In the vegetable garden: Cool-season vegetables and herbs tolerate freezing temperatures but small seedlings can be affected. Cover tender growth if you are expecting freezing temperatures with frost cloth, also known as reemay. If your vegetables need a boost of fertilizer, side-dress with a teaspoon of complete fertilizer placed a couple of inches from the base of the plant.
  2. In the lawn: If you over-seeded with annual ryegrass, mow regularly to keep the lawn looking tidy. If winter weeds are bad, it is safe to apply broad leaf weed killer following label directions, or hand pull them.
  3. In the landscape beds: Keep winter weeds in check by applying mulch at a 2-to-4-inch depth. Pine straw, leaves and pine bark are all excellent choices. Plant chilled tulips and hyacinths into the garden this month.
  4. Trees and shrubs: This is a great time to plant trees and shrubs while temperatures are down. This is also a good time to relocate established trees and shrubs that you want moved elsewhere in the yard. Be sure to go out a foot or more from the trunk of the tree or shrub to get an adequate root ball. Water newly transplanted trees in well to help encourage new root growth.
  5. Fruit: Cover tender fruit trees, such as citrus, when temperatures are set to drop into the mid-20s overnight. Wrap or drape the plants with canvas or another type of fabric extending all the way to the ground. Place the cover on trees during the day to trap radiant heat coming up from the soil. Fertilize citrus at the end of January to early February. Apply 1 to 1 ½ pounds of 8-8-8 or 13-13-13 per year of tree. Year one equals 1 to 1 ½ pounds, year two equals 2 to 3 pounds and year three equals 3 to 4 ½, and so on.

February

  1. In the vegetable garden: Plant warm-season vegetables late this month to decrease the chance of disease and insect problems. Be prepared to cover plants in freezing temperatures. Cut seed potatoes with a couple of eyes about the size of a golf ball and plant 4 inches deep and 12 inches apart. Corn planted in late this month will have few earworms.
  2. In the lawn: Time to relax and rejuvenate. Perform lawn equipment maintenance this month in preparation for the spring and summer. Dormant sodding can be done this month if you have new construction or need to stabilize bare patches in the lawn. The warm-season turf is dormant and will be brown but will green up in spring.
  3. In the landscape beds: Fertilize Louisiana irises and calla lilies and other fall-planted spring-flowering bulbs and cool-season annuals with a slow-release granular fertilizer this month. Prune repeat-blooming roses.
  4. Trees and shrubs: Prune your roses on or around Valentine’s Day and begin a preventative spray program, alternating fungicides for blackspot and powdery mildew. Fertilize spring-blooming trees and shrubs.
  5. Fruit: Time to fertilize fruit trees and shrubs, including apples, peaches, citrus, figs, blueberries and blackberries. Dormant cuttings from fig trees can be taken from 1-year-old growth and stored at 40 degrees for a month or so before rooting in moist media.

Heather Kirk-Ballard, Ph.D.
Consumer Horticulture Specialist

04_Leek_02jpg
Leeks

Low ornamental blushes with green leaves and small orange and yellow blossoms, surrounded by light brown pine straw mulch.
Pine straw mulch

General Winter Vegetable Planting Tips


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!

December

  • Scout lettuce, strawberries and all cole crops for insects. Aphids, slugs, snails and worms tend to cause problem 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 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, or 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 them 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 technology that can make gardening easy, especially in larger gardens. To control grasses in the garden use Poast or other herbicides with the active ingredient sethoxydim to kill grass and 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!

Enjoy the Garden,

Kathryn “Kiki” Fontenot, Ph.D.
Associate Professor
LSU AgCenter School of Plant, Environmental and Soil Sciences

Several rows of strawberry plants covered in white and black plastic in a field.
Strawberry plants covered to protect them from below freezing temperatures.

A bushel of purplish red onions sitting on a shelf.
Red Burgandy onions

General Winter Vegetable Planting Tips


The dormant season for turfgrass begins in December

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.

Soil sampling and pH adjustments

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.

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. 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 (formerly brown patch)

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.

Winter weed management

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.

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.

Ron Strahan, Ph.D.
Associate Professor
Turfgrass and Weed Science

Plant with fine textured foliage that will eventually develop spiny seed heads
Lawn burweed germinates in lawns fall and produces painfull stickers in the spring.

Seed head has alternate seed structures. Seed head is wide at the bottom and narrows at the top.
Annual bluegrass seedhead

A light green plant with long stems with thin and narrow leaves whorled around the stem. Beneath the catchweed bedstraw is a dark green turfgrass.
Catchweed bedstraw is a sticky winter weed that attaches to pants and pets.

The plant is surrounded by loose pine straw. The leaves are grouped in small leaflets and there is a red mature fruit on the mock strawberry.
Wild geranium is a common winter broadleaf infesting lawns.

Round shaped plant with thin red stems with one leaf at the end of each stem. Leaves are deeply lobed.
Mock strawberry

Sooty Molds


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

Small red insects cover the new growth foliage of a plant. The insects are on the top and bottom of the leaves.
Figure 1: Aphids feeding on a weed host.

Underside of a leaf showing several small white bodied insects. Their two white wings cover most of their body. Also visible are their small legs and antennae.
Figure 2: Whiteflies feeding on the underside of a holly leaf.

Small bodied scale insects on a tree branch. The insects are grouped tightly together and cover a large patch of the bark.
Figure 3: Crape myrtle bark scale on a crape myrtle trunk.

Black film on crape myrtle leaf's surface. The black film is thicker in places and thinner in others. This is called sooty mold.
Figure 4: Crape myrtle leaves covered with sooty mold.

Black film on citrus leaves and a citrus fruit.
Figure 5: Citrus fruit and leaves covered with sooty mold.

A group of crape myrtle leaves that are shiny because there is a substance called honeydew on the leaves.
Figure 6: Honeydew present on the upper surface of crape myrtle leaves.

Close up of a rose leaf with a shiny liquid on the leaf's surface. This liquid is called honeydew. There are several tiny bodied aphid insects on the leaf's surface.
Figure 7: Honeydew present on the upper surface of a rose leaf.

Picture of the side of a shrub with several leaves having a black film on leaf's surface. Some leaves are losing their green color and turning yellow. There are small red berries attached to the shrub.
Figure 8: An Indian hawthorn covered with sooty mold planted under a large tree infested with aphids.

A picture looking at the ground below a crape myrtle tree. The mulch surrounding the tree has a black tint because of sooty mold.
Figure 9: Mulch covered with sooty mold under a crape myrtle tree heavily infested with crape myrtle bark scale.
12/23/2021 5:35:13 PM
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