Horticulture Hints for Louisiana - Summer 2023

Jessie Hoover, Singh, Raghuwinder, Strahan, Ronald E., Hawkins, Keith, Afton, William, Fontenot, Kathryn, Mathews, Marcie

LSU AgCenter, Research, Extension, Teaching. Horticulture Hints for Louisiana. Summer 2023.

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This photograph displays a mayhaw tree ready to be harvested with a tarp below to catch any fallen fruit.
A mayhaw tree bearing fruit. To make harvesting easy, a tarp can be laid out at the base of the tree to catch any fallen fruit.

The Best Little Multipurpose Tree for Your Landscape

Utilizing native plants in the landscape is becoming very popular across Louisiana. Natives are a good option because they are adapted to our hot, humid climate and usually have more tolerance for pests and diseases. We have many good native options in Louisiana, and it makes sense to utilize them in our landscapes rather than try to force non-natives to behave correctly. For those of you looking for an interesting native to add to your landscape, let me suggest a mayhaw tree.

Mayhaws grow wild in river bottoms, swamps and waterways across Louisiana and are famous for the jelly made from their small, tart berries. Mayhaw fruit is a wonderful benefit to owning a mayhaw tree, but I feel like their ornamental value is often overlooked. Mayhaws produce lovely white blooms and are one of the earliest blooming trees in the Deep South, paving the way for spring. They bloom around the end of February and early March, and the fruit ripens in April and May.

Mayhaws are a smaller tree that will fit in many places around your landscapes. They grow slowly and can reach up to 30 feet tall, but generally stay around 15-20 feet tall. They also have a very pleasant shape which adds character to your landscape. Some mayhaw varieties have what I refer to as an “upside down umbrella” shape with branches reaching up to the sun creating a vase effect. Other mayhaw varieties have a more traditional round shape to their canopy.

In addition to ornamental value, the mayhaw is a great tree to attract wildlife to your landscape. During bloom, bees are attracted to mayhaw flowers and pollinate the trees. Birds, squirrels and other wildlife enjoy mayhaw fruit, and the thorny branches make a secure, protected space for birds to nest.

Mayhaw fruits range in color from yellow-orange to bright red. These cheerfully colored fruits add another attractive element to your landscapes. Mayhaw fruits are also relatively small, about the size of a cranberry. This makes them harder to harvest, but if you do not plan on harvesting your mayhaws, the small size makes them easy to run over with a lawn mower. They will not cause a significant amount of rot and bumps in your yard as sometimes happens with unharvested pears and other large fruits.

The majority of mayhaw enthusiasts harvest their mayhaws and enjoy making jelly, syrups, drinks and baked goods from the fruit. Homeowners generally pick up mayhaws from the ground by hand. The thorny branches make it hard to harvest the fruit directly from the tree, so you can wait until the fruit naturally falls, or give the tree a good shake and cause more fruit to fall to the ground. Another method for mayhaw collection is to lay collection nets or tarps on the ground to collect the fruit as it falls. The fruit should be harvested daily to ensure peak freshness.

Once the fruit has been collected, the juice can be extracted fresh, or the fruit can be frozen for juice extraction later. Here is an excerpt taken from the LSU AgCenter publication 2484, The Mayhaw, with instructions on processing mayhaw juice:

Sort mayhaws, removing decayed fruit and trash. You can leave the tiny stems and dark blossom end on the fruit. Wash thoroughly. Measure or weigh fruit and put in large saucepan. For each gallon (4 quarts or about 4 1/2 pounds) of mayhaws, cover with 3 quarts (12 cups) of water. For 2 quarts of fruit (a little over 2 pounds), cover with 6 cups water. Bring to a boil, cover and cook gently for about 30 minutes. Cool and drain juice first through a colander, pressing fruit lightly with the back of a spoon. Then strain the juice through two or three thicknesses of damp cheesecloth, a jelly bag or a clean thin white cloth. Leave the sediment that settles to the bottom. From 1 gallon of mayhaws you should have about 12 cups of strained juice. This will make three batches of jelly.

The mayhaw is a wonderful, multipurpose, native tree for your landscapes. Not only can it be utilized as a fruit tree, but it also has aesthetic value and attracts wildlife. Mayhaw trees can usually be found in independent garden centers or by contacting growers through the Louisiana Mayhaw Association at www.mayhaw.org. The Louisiana Mayhaw Association has a list of sellers for trees, juice and berries.

Jessie Hoover
Extension Agent

Tree Planting Considerations

This photograph displays branches of a tree obscuring the view of a stop sign at a street corner.
One tree obstructing a stop sign.

Homeowners who aspire to add trees to their landscapes would be well advised to consider other potential issues. A free, downloadable publication from the AgCenter, Native Tree Growing Guide for Louisiana, provides sixteen pages of good advice for an attractive, shady landscape.

To save future headaches, here are some things to avoid with respect to tree planting:

  • Planting large trees under utility lines.
  • Blocking traffic signs or views at corners.
  • Planting trees or shrubs too close to ground transformers.
  • Planting large trees too close to buildings. Planting closer than 20 feet is risky.
  • Blocking windows or desirable views.
  • Planting where roots will damage pavement.
  • Spacing trees too closely or shading gardens.
  • Encroaching on your neighbor.
This photograph displays flower blossoms of redbud on a tree branch.
Two flowers of redbud.

This publication addresses the why, where, what, when and how of tree planting in some detail. On the back page, there is an instructive list of native trees to consider for landscaping. There are specific lists for different purposes:

  • Trees preferring an acid soil.
  • Trees tolerating dry conditions.
  • Medium to large flower trees.
  • Small flowering trees.
  • Trees tolerating less than ideal drainage.
  • Trees with attractive berries or fruit.
  • Trees with edible fruit or seeds.
  • Trees frequently providing good fall color.
  • Fast growing shade trees (up to a certain size).
  • Trees with interesting trunks.
  • Evergreen trees.
  • Trees that attract birds.

If you have concerns about landscape trees, contact your local agent or extension forester and ask for a site visit to examine your tree and to receive recommendations.

The area horticulture agent for Allen, Beauregard, Evangeline, Rapides and Vernon parishes is Keith Hawkins.

For more information, email khawkins@agcenter.lsu.edu or call 337-463-7009.

Keith Hawkins
Area Horticulture Agent

Louisiana Native Plants

This photograph displays flower blossoms of aquatic milkweed. data-verified=
Aquatic Milkweed, Asclepias perennis.

What is a native plant?

It is a plant species that occurs naturally in a particular region or area.

This photograph displays a sensitive plant flower.
Sensitive Plant, Mimosa strigillosa.

What are the different types of native plants?

  • Wildflowers.
  • Trees.
  • Shrubs.
  • Vines.
  • Aquatic.

Herbaceous plants that don’t fall into the above categories such as weeds and wild edible plants.

This photograph displays flower blossoms of the american groundnut.
American groundnut, Apios americana.

Why are native plants important?

  • Wildlife relies on native plants as a food source and shelter.
  • Native plants attract pollinators to our landscapes.
  • Native plants are particularly suited to our climate, thus making them hardy and easy to grow. This makes native plants a welcomed addition to our gardens.

What are some popular Louisiana native plants with ornamental appeal?

  • Passion vine (maypop).
  • Black-eyed Susan.
  • Coneflowers.
  • Hibiscus.
  • Iris.
  • Asters.
  • Ferns.
  • Coral honeysuckle.
  • Verbena.
  • Milkweeds.
  • Sunflowers.
  • Spanish moss.
  • Beautyberry.
  • Magnolia.
  • Bald cypress.
  • Gaura.
  • Clematis.
  • Water lily.
This photograph displays flower blossoms of the passion vine.
Passionvine, Passiflora incarnata.
This photograph displays a stem with American beautyberry fruit.
American Beautyberry, Callicarpa americana.
This photograph displays flower blossoms of the blue mistflower.
Blue Mistflower, Conoclinium coelestinum.
This photograph displays several Louisiana native irises in the wild.
Louisiana Native Irises

Native plants with ‘Louisiana’ in the common or scientific name:

  • Louisiana cupgrass.
  • Louisiana bluestar.
  • Louisiana goldenrod.
  • Louisiana nerveray.
  • Louisiana catchfly.
  • Louisiana sedge.
  • Louisiana flatsedge.
  • Louisiana vetch.
  • Louisiana quillwort.
  • Louisiana wake robin.
  • Louisiana endangered native plants
  • Louisiana Quillwort.
  • American Chaffseed.

How do you go about starting a native plant garden or collection? There are many retailers that sell Louisiana native plants. You can also purchase seed online and grow at home. Get a start or seedling of one from a friend, Collect seed while on a nature hike. Leave specimens growing in the wild, and do not attempt to harvest and transplant without special permission. Over harvesting disrupts the environment and can lead to endangerment. Native plants can be rather difficult to transplant and usually end up dying because they are so acclimated to their growing conditions (light, soil, water, etc.) If you are attempting to transplant native plants from the wild into your garden, be sure conditions are comparable. If you don’t think it will make it in your yard, it is best to leave it where it is and enjoy it from afar. And as always, never trespass or harvest without permission. Survey your own properties; you never know what treasures you may find. Native plant cultivars sold in nurseries and garden centers are better suited for landscaping. Another way to collect is simply by viewing hikes, trails and roadsides and taking pictures. Finding plants growing in their native habitats (especially rare or hard to find ones) is very rewarding and breath taking. We have so many beautiful species growing right in our own backyards. Get out and enjoy!

Marcie Wilson
Horticulture Agent, Northeast Region

Be Aware of Yellow Poplar Weevil

This photograph displays a magnolia flower which has been damaged by the yellow poplar weevil.
A magnolia flower showing signs of yellow poplar weevil damage.

Southern magnolia, Magnolia grandiflora, is not only the state flower of Louisiana, but it is also a prominent member of the local ecosystem and a popular landscape plant throughout the southeastern United States. We enjoy our magnolias, and when they do not look right, we get concerned.

Spring leaf drop causes a little concern in magnolia owners. It’s when the oldest leaves naturally abscise and fall to the ground during the late winter, early spring period. New tree owners may think that something is wrong, but experienced gardeners know that soon new leaves will emerge to replace those older leaves and give the trees a fresh appearance.

A situation happened earlier this year involving a magnolia tree, necrotic leaf tips and holes being eaten in most new leaves. These symptoms appeared in April and May when magnolia buds started to become active. As the season progressed, symptoms progressed throughout the entire canopy. Something was going on and it couldn’t be explained through annual changes in the environment. Finally, a small beetle was identified to be the culprit.

The yellow poplar weevil, Odontopus calceatus, goes by a few common names. Some refer to it as the sassafras weevil while others say tuliptree leafminer or magnolia leafminer. The reason for various names comes from the fact that the yellow poplar weevil can feed on tuliptrees (Liriodendron tulipifera), sassafras trees (Sassafras albidum) and magnolia trees (Magnolia spp.). Weevils are a type of beetle and are members of the order coleoptera. They have a characteristic elongated snout. The adult yellow poplar weevil overwinters in leaf debris around host trees. As the first days of spring start to warm, the adults fly up into the canopy and start feeding on buds and leaves as the trees also awaken from dormancy. These adults lay eggs inside the midrib of the leaves. In May and June, these eggs begin hatching and the young developing larvae mine within the leaf for food. The larval feeding of yellow poplar weevils typically produces large necrotic leaf tips commonly described by victims for their infestations. As these larvae mature and eventually become adults they continue feeding in the canopy through June. By the end of July, adult activity subsides as they disappear into the forest floor, mulched area or leaf litter below the tree.

This photograph displays a magnolia flower which has been damaged by the yellow poplar weevil.
Another magnolia flower showing signs of yellow poplar weevil damage.

If these symptoms are observed and adult beetles are found on the leaves then it’s safe to say that there is a yellow poplar weevil infestation. Start a control program by collecting the fallen leaves and disposing of fallen leaves throughout the root zone area. Remember this intervenes with the overwintering behavior of adults. To manage the current population, most insecticide options labeled for use on landscape plants should control these pests. Mature trees present an issue for the homeowner due to not having the proper equipment to get decent coverage in the canopy. Treat young trees, newly planted trees and trees with a manageable height with a contact insecticide. Look at popular active ingredients like permethrin (Bonide Eight, Martin’s Permethrin SFR), zeta-cypermethrin (Ortho Bug B Gon), and carbaryl (GardenTech Sevin) to apply on newly planted and young trees within a manageable height. Systemic insecticides can be applied to the root where the active ingredient is taken up and circulated inside that plant. It provides control as the pest feeds. Make systemic insecticide applications once new growth emerges in spring. It will take several weeks for the product to fully circulate in the tree, but it helps manage the June hatch. And don’t forget to read the product label before applying a pesticide product.

It will take the whole growing season to correct but these sporadic insect pests, but they can be controlled easily when identified early on. It’s helpful to keep in mind that these beetles do not kill trees but rather they occasionally hinder the tree’s appearance during heavy infestations. Noticeable outbreaks tend to reduce over time due to parasites that build up within the weevil populations. Louisiana, with its long growing season, provides opportunities for mature trees to compensate for any damage from early in the season.

William Afton
St Tammany Parish Agent

Slimy Slugs and Snails Can Be Pesky Pests

This photograph displays a slug feeding on strawberry fruit.
A slug feeding on strawberry fruit.

We all know that pathogens and insect pests can cause severe damage to vegetables, fruits and ornamentals in home gardens and landscapes. But do you know that slimy slugs and snails also can cause considerable damage to vegetables, fruits and ornamentals, if not controlled?

Slugs and snails are mollusks, and there are several species that can be pests in gardens and landscapes. Both slugs and snails are practically the same except snails have external shells. They leave slimy trails of mucus that facilitate their movement. Dried slimy mucus turns white or silvery and can be a good indication of the presence of slugs and snails. They are hermaphrodites which means all adults can lay eggs. Eggs are small, clear to white, and laid in batches in soil beneath leaf material, mulch or other protected places.

Slugs and snails are usually active during the night but can be spotted during early morning hours before the sunrise. During daytime they hide and take shelter under plant materials or mulch.

They can feed almost on any living or dead plant material, but they prefer young, tender succulent plant tissue. They chew on the leaves and flowers and produce irregular holes. Fruits damaged by slugs and snails are unsightly. The presence of dried white mucous trails on the affected tissue is a way to diagnose slug or snail damage.

A slug feeding on zinnia leaves.
A slug feeding on zinnia leaves.

Slugs and snails can be effectively managed by using different tactics or a combination of these tactics. Beer traps, baits, barriers and hand picking are some of the common management options available.

While hand picking can be an effective tactic, it may be labor intensive and time consuming, and some folks do not like to handle slimy things.

Beer traps can be very effective in managing slugs and snails in small gardens or vegetable beds. Fermented products attract them, and they die due to drowning in these products.

Metal or chemical barriers are other effective ways to get rid of these pesky pests. Barriers containing copper-foil react with the slimy mucous and disrupt their nervous system. Bordeaux mixtures containing copper sulfate and hydrated lime are known to repel slugs and snails.

Several baits are available from garden centers and retail stores to manage slugs and snails. Baits containing metaldehyde as an active ingredient are toxic to pets so avoid using them around areas where children and pets could encounter them. Always follow the bait label for the recommended dose and application methods.

Raj Singh, D.P.M.
Associate Professor,
Horticulture Pathology
Extension Specialist

Louisiana Vegetable Gardening

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Happy summer, gardeners!

Have you ever caught yourself saying, “This weather is just not normal”? I say it all the time. But when I look back at my garden notes, to be honest, there are no real trends. Some springs are wet, some are cool, some are smoldering hot. What we can rely on is summer weather – hot, humid, buggy! That pretty much sums up summer in Louisiana each year. This summer of 2023 we are coming off an unusually (ha ha) cool spring. Many of you might have noticed your okra and cucurbits (cucumbers, melons, squash, gourds, etc.) were delayed in germinating and almost stunted in growth. These crops plus peppers and southern peas grow more rapidly when the temperatures rise. Well, we know June will bring heat, so check out the tips below on growing a great garden this summer.

  1. Always have water on hand. A garden looks much better when the gardener is still upright and not lying on the ground. Keep yourself hydrated even if you are only working for 10 minutes at a time.
  2. Pull out any cool-season crops still lingering in the garden. They are probably bolting and at this point just harboring unwanted insects.
  3. If you haven’t done so yet, add mulch. The weeds will take over the garden in the summer, so, mulch, mulch, mulch! The best mulches around vegetable crops are leaves, pine straw, hay or anything other than wood chips.
  4. Install drip hoses or drip irrigation in the garden. We are guaranteed to have disease this summer. By watering at the base of the plant, you reduce the unintentional spread of fungus and bacteria.


In mid-June, plant a summer crop of heat set tomatoes. Planting heat set tomatoes is very important. These cultivars have been bred to set fruit during periods with high nighttime temperatures whereas other cultivars will not. If managed correctly, heat set tomatoes will produce fruit until a frost or freeze. Preferred heat set varieties include Tribute, Floralina, Heatwave II, Phoenix, Florida 91, Solar Fire, Sun Master, Sunbeam, Sunchaser, Sun Leaper, Talladega and Bella Rosa among others. Heat set tomatoes can be planted again in late July for fall tomato production.

Collard greens, cucumbers, watermelon, cantaloupe, okra, southern peas, pumpkins and summer squash can all be directly seeded into the garden during June. Start transplants of eggplants and peppers during June as well.

This photograph displays a pumpkin plant with a single fruit on it growing in a 12-inch hanging basket.
Miniature pumpkins can be grown in containers and even hanging baskets if you are limited on space. However, planting pumpkins directly in the ground will yield much more fruit per vine.


Transplant a fall crop of heat set tomatoes and bell peppers. Direct seed okra, southern peas, cucumbers, squash, cantaloupe, pumpkins and watermelons throughout July. Late June through mid-July is the optimum time to plant pumpkins for a Halloween harvest.

Late July through early August is a good time to start thinking about your fall garden. Order broccoli, Brussels sprouts, cauliflower, Chinese cabbage, cabbage, collard green, mustard green, kale, turnip, radish and other fall crop seeds. If you want an early September planting of these crops, start seed in seedling trays in early August. Start your seed outdoors in a sunny area that is protected from foot traffic. Greenhouse or cold frames are not needed to start a fall crop as the weather is so warm. However, you need to water transplants daily so make sure they are in a very visible location. Start seed five to six weeks prior to the desired transplant date for broccoli, Brussels sprouts, cauliflower, Chinese cabbage and cabbage. Greens, such as kale, Swiss chard, mustard and collards, can be started as transplants or directly sown into the garden.


Plant bush snap and bush lima beans throughout August. Transplant broccoli and Brussels sprouts as early as mid-August in the garden. In north Louisiana, start your lettuce seed and plant beet and Irish potato seed in the garden.

In late August, south Louisiana gardeners can start their lettuce seed, and plant beet and Irish potato seed into the garden. All gardeners regardless of location, can plant transplants of broccoli, Brussels sprouts, cauliflower, Chinese cabbage, cabbage, cucumbers, squash, mustard greens and shallot sets in late August. Be cautious when doing this because insect pressure and heat are very high. Planting an early fall garden in late August requires time, care and scouting. Don’t go on a vacation – or go on vacation, and you’ll find yourself repeating this advice mid-September through October.

Crop Highlights

Squash and cucumbers. These two crops can be planted in June, July and August. Summer plantings are harvested in roughly six weeks. Yields usually are lower than spring plantings. A fall crop of yellow summer squash, zucchini and cucumbers can be grown by planting seeds during August. Squash vine borers may be a more severe problem during fall than spring, so be prepared to control them with an insecticide or use floating row covers until the plants start to bloom. After they bloom remove covers to allow pollinators to visit crops. Viruses are a problem during the fall. The best cucumber to plant is Dasher II.

Pumpkins. To grow pumpkins for Halloween, plant in early to mid-July. Apply 3-5 pounds of a complete fertilizer (13-13-13) for every 100 feet of row before planting. Plant five to six seeds in hills about 4 to 5 feet apart in rows 6 to 8 feet apart. Thin to one or two plants per hill. Apply a side-dressing of 2 pounds of calcium or potassium nitrate per 100 feet of row when vines begin to run. Keep soil moist for best production. Sunlight, Darling, Orange Smoothie, Cinderella, Silver Moon and Conestoga are excellent varieties to grow for Halloween. Recommended varieties of giant pumpkins are Atlantic Giant and Prize Winner. However, growing giant pumpkins is difficult because of disease pressure and our hot and humid climate. Don’t fret if you do not reach award winning sizes. Watch for worms, slugs and snails, and spray insecticides when you start to see these pests.

Fall tomatoes. Transplant fall tomatoes late-June and July. Be prepared to spray with insecticides and fungicides. Insect and disease pressure usually is worse in the summer as compared to the spring. Recommended heat set varieties include Solar Fire, Sun Master, Solar Set, Bella Rosa, Florida 91 and Phoenix. These varieties can set some fruit during times of high temperatures, allowing the fruit to mature before cool weather. Row covers, which protect the plants from the first frost, have prolonged the harvest period, and they enhance fruit maturity. Since fall tomatoes are a crop you can’t really be sure of, it’s interesting to try several early varieties. Certain varieties may produce better in some parts of the state than others because of the variation in climate and soils. A well-watered and fertilized tomato shrub can handle insect and disease pressure much better than a weak, ignored plant. If you are gardening in the summer, you simply cannot ignore the garden for weeks at a time unless you enjoy weeds and bugs.

Kathryn “Kiki” Fontenot, Ph.D.
Vegetable Gardening Specialist
LSU AgCenter School of Plant,
Environmental and Soil Sciences

Tips for Summer Care of Turfgrass

Spring and summer are the peak growing seasons for lawns in Louisiana. If you did not fertilize during the spring, you still have time to fertilize and get your yard in good shape prior to fall. Keep up a good fertility program through early to late August. Remember to apply all granular materials on a dry lawn and water very soon after application. Make sure lawns are getting adequate amounts of moisture during the summer months, but don’t overwater. Water deeply only once or twice per week, or as needed, based on the amount of rainfall. The purpose of irrigation is to supplement rainfall. I am not a fan of watering lawns everyday unless we are in severe drought.

Consider aerifying compacted soil. I’ve seen aerification completely change thin lawns caused by compacted soil into thick and healthy turf. Aerifying helps with water percolation, increases the turf’s rooting depth and makes for a more drought tolerant lawn. Lawn care companies can be hired to aerate your yard, or you can rent an aerator from a rental store and do it yourself. If your soil is prone to compaction, consider aerating one to three times this growing season. Aeration may be the game changer that your lawn is missing.

Fertilizing the lawn

St. Augustinegrass and zoysia both respond well to fertilizer applications. St. Augustinegrass may be fertilized up to three times during the growing season in April, June and mid-August. Fertilize zoysia twice per growing season in April and again in July.

Bermudagrass is an even bigger fertilizer user and can be fertilized from three to five times during the growing season, especially if you like to mow grass. Carpetgrass and centipedegrass are not big fertilizer users. Up to two applications – one in April and an option one in July – will take care of centipedegrass, and a single application in April will be sufficient for carpetgrass.

Centipedegrass should receive its second and final fertilizer application in July. For centipedegrass, apply only 0.5 pounds of actual nitrogen per 1,000 square feet. For example, apply 3 pounds of 17-0-17 per 1,000 square feet or 5 pounds of 10-0-10 per 1,000 square feet. St. Augustinegrass would need 6 and 10 pounds of the fertilizer.

If your lawn is not performing well, there could be a nutrient deficiency in the soil. The only surefire way to know what your soil needs is to collect a soil sample and submit it for testing at the LSU Soil Testing and Plant Analysis Lab. In order to simplify the soil sampling and submission process, there are pre-addressed submission boxes with sampling instructions at several garden centers throughout the state and at your local parish extension office. Once submitted, the results will be sent to your home mailbox and/or email usually in less than two weeks. Your parish LSU AgCenter extension agent can help you interpret the results from the soil sample and tell you exactly what’s needed nutrient-wise to make your lawn beautiful.

Correct mowing heights are highly important

You may not know this, but there is a correct mowing height for your lawn. St. Augustinegrass is very finicky when it comes to mowing height. Don’t cut it too short and don’t allow it to get too tall. It likes to be maintained around 3 inches, the tallest mowing height of all the lawns grown in Louisiana. If you cut St. Augustinegrass too short, it becomes stressed and more prone to disease and weed infestations.

Centipedegrass is often maintained too tall. Centipedegrass should be mowed to 1 to 1.5 inches. This helps prevent thatch buildup. Zoysia also likes to be mowed in the 1-to-1.5-inch range. Bermudagrass should be mowed from 1 to 2 inches, and shorter mowing heights are better when more frequent mowing is possible. Keep mower blades sharp to ensure a clean cut and good lawn health.

Insect pests

Watch for chinch bugs in St. Augustinegrass and bermudagrass lawns and treat with an LSU AgCenter recommended insecticide such as bifenthrin (Talstar and other trade names). Chinch bug problems show up as yellowish-brown to straw-colored areas of the lawn during hot, dry weather. These insects extract plant juices from turfgrass stems and crowns while pumping toxic salivary fluids into the lawn. The fluids disrupt the plant’s vascular system. The damage resembles herbicide damage.

Check for chinch bugs in the lawn by saturating suspected areas with a gallon of water mixed with a few squirts of lemon dishwashing soap. This soapy solution irritates chinch bugs and brings them up near the grass surface so you can see them and determine if the bugs are causing the lawn damage. If it is hot and dry and there are dead spots in your St. Augustinegrass, chinch bugs are the first thing that I would consider.

Additional insect problems that appear during the summer include armyworms and tropical sod webworms. These moth larvae or “worms” can cause severe lawn damage very quickly and will need to be killed with insecticides to prevent further damage. Tropical sod webworms can devastate St. Augustinegrass and carpetgrass lawns. Tropical sod webworms crushed St. Augustinegrass in 2020. However, populations were not severe in the 2021 growing season. Armyworms prefer bermudagrass and can completely defoliate acres of pasture and lawns. Carbaryl, bifenthrin and chlorantraniliprole insecticides are options for tropical sod webworms, armyworms, as well as chinch bugs infesting the lawn.

Be mindful of these pests as you walk through your lawn. Investigate damaged areas and treat them accordingly.

Virginia buttonweed and other summer weeds

This photograph displays a concrete deck through which virgina buttonweed is emerging through cracks.
Virginia buttonweed emerging between concrete slabs.

In late spring to early summer, Virginia buttonweed starts forming mats that can eventually smother out the lawn. Pull up small populations of Virginia buttonweed or carefully treat with herbicides like metsulfuron (MSM Turf and other trade names) or Celsius. These herbicides work well with repeated applications spaced four to six weeks apart. Metsulfuron and Celsius can be safely applied on St. Augustinegrass, centipedegrass, bermudagrass and zoysia during warm weather. Carpetgrass will be damaged by Celsius herbicide. Bahiagrass will not tolerate metsulfuron or Celsius. When it comes to “managing” buttonweed, it is important to start spraying early in the growing season (April) and spray often. Don’t wait until September to make your first herbicide application.

Common lespedeza is a mat-forming annual legume that emerges in the spring and lingers deep into fall throughout Louisiana. By late summer, the plant matures and becomes woody-like and tough on lawnmower blades. Metsulfuron works well on this weed, but early summer applications are more effective.

This photograph displays a centipedegrass lawn that is being infested with torpedograss.
Torpedograss infesting centipedegrass.

Torpedograss is a perennial grass that’s mainly a problem in south Louisiana, but I do get calls from north Louisiana as well. There are few lawn problems more devastating than a torpedograss infestation. Torpedograss is extremely tolerant of herbicides and easily outcompetes slow growing grasses like centipedegrass.

The weed often starts from soil brought in during flower bed construction. However, it quickly spreads from the flower bed to the lawn. The ability to suppress torpedograss in lawns depends on the turfgrass species. Selectively removing torpedograss out of lawn grasses and sports fields is rarely completely achievable. Quinclorac (Drive and other trade names) is an herbicide that is somewhat effective in suppressing torpedograss in bermudagrass and zoysia. Unfortunately, you cannot use quinclorac in centipedegrass and St. Augustinegrass.

Sethoxydim (Bonide Grass Beater and other trade names) will temporarily injure torpedograss infesting centipedegrass, but it does not provide long-term control. The torpedograss recovers and the weed reinfests the centipedegrass again. Unfortunately, there are no selective herbicide options for torpedograss infesting St. Augustinegrass. Often, complete renovation is necessary when centipedegrass and St. Augustinegrass are severely infested.

If you decide to renovate and install a new lawn, consider sodding the lawn with zoysia (semi-shady or full sun lawns) or bermudagrass (for full sun only). Converting to zoysia or bermudagrass will allow the use of quinclorac, the most effective selective herbicide on torpedograss. Installing zoysia may be the better fit for Louisiana because of its good shade and drought tolerance. Zoysia is not a high maintenance grass when managed properly. Maintain zoysia at 1 to 1.5 inches with a sharp mower blade and fertilize twice per year. There are several sod farmers in Louisiana that grow zoysia, so it is readily available.

Proper lawn maintenance keeps your lawn healthy and reduces the need for the use of pesticides. If it becomes necessary to use a pesticide in the lawn, it is highly important to always read and follow their labels before using. The label will tell you how to use the product safely to achieve satisfactory results. You will find the label attached to the product’s container.

Ron Strahan, Ph.D.
Associate Professor
Turfgrass Science/ Weed Science
LSU AgCenter

7/12/2023 8:04:19 PM
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