Hello Gardeners,

This has been a tough year for lawn grass in Lafayette Parish and South Louisiana. I received numerous calls from homeowners concerned about the poor performance of their lawns, especially St. Augustine and Centipede grass. Upon evaluation of these lawns, I found many that had areas with two to three inches of thatch. Thatch is an accumulation of organic matter, primarily dead leaves and stems that cause serious problems in lawns. If a lawn feels spongy when walked upon, that often suggests a thatch problem. Thatch accumulates when organic matter accumulates faster than it can decompose. The roots of the lawn grass will grow into the thatch which can lead to an increase of insect and disease problems. The reason why many of the St. Augustine and Centipede lawns struggled this growing season relates to the unusually cold winter and cold injury because roots growing in the thatch were more susceptible to cold injury than the roots that would have been growing in soil. A thatch problem in a lawn has to be addressed by dethatching with either a motorized thatching machine or a dethatching rake. Removing thatch should be done in early to mid-April to allow an application of fertilizer. Removing thatch shocks the grass, so a fertilizer application is recommended in order to help the lawn grass to recover. The final issue with thatch is that it remains wet when rain comes frequently, but when the thatch dries it gets extremely dry. Neither situation is good for lawn grass.

One of the most common diseases of warm season turf grasses in Louisiana is Large Patch (also called Brown Patch). Every growing season, I get numerous calls from concerned gardeners regarding dead areas in their lawns. Brown Patch disease primarily occurs when night time temperatures begin to consistently drop below 70 degrees — in the fall, late winter and early spring. Since moisture also promotes Brown Patch activity, periods of rain make the disease spread rapidly. While brown patch can affect all warm season lawn grasses, it is usually more prevalent in St. Augustine lawns. The symptoms usually begin as a small irregular patches of brown areas in the lawn. With mild temperatures and rainfall these areas can enlarge rapidly. Once these areas of the grass are weakened and thinned by brown patch, weeds begin to invade. If a lawn has a history of brown patch disease, a couple of fall applications of fungicide can limit the impact of Brown Patch. Once conditions favor disease development, it is recommended that fungicide applications begin. For this area, that first application should be made between mid and late September, followed by a second application mid to late October. If conditions remain favorable for disease development into November and December, additional fungicide applications may be necessary. Since many fungicides labeled for lawns will have activity on brown patch, homeowners should be able to find these fungicides at retail nurseries and garden centers as well as feed and seed stores. According to Dr. Ron Strahan, Lawn & Turf Specialist with the LSU AgCenter, the two most effective fungicides for addressing brown patch problems in lawns are fungicides containing azoxystrobin or thiophanate methyl. If brown patch is not visible and the homeowner wants to be proactive, then granular fungicides are recommended. If however brown patch has already been identified in the lawn, the liquid fungicides applied as a spray are most effective. If we have a mild winter where the lawn does not go fully dormant, it is possible that brown patch will be present throughout the winter months and into the spring. If that happens, then homeowners may want to consider applying several applications of fungicides through winter and into the spring.

Finally, I am also getting calls from homeowners who are asking for fertilizer recommendations for their St. Augustine lawns. According to Dr. Strahan, St. Augustine responds to three applications of fertilizer annually: in mid-April , mid –June and Mid- August. In my opinion, it is now too late to fertilize St. Augustine lawns. Fertilizing now, especially with a fertilizer containing nitrogen, can aggravate brown patch disease. It can delay dormancy which could make St. Augustine lawns more susceptible to cold injury. There are fertilizers available called winterizing fertilizers that can be applied in fall, but here in South Louisiana if a homeowner decides to apply a winterizing fertilizer, it should not contain any nitrogen (N), it should contain primarily potassium (K).

Happy Gardening!!!Happy Gardening!!!Gerald P. Roberts

Hello Gardeners,

By mid-to-late summer, I usually receive numerous calls from concerned homeowners regarding a variety of plants such as crape myrtles, gardenias, citrus, tomatoes, camellias, and pecans that have leaves covered with a crusty black substance. The complaint often describes leaves yellowing or dropping and the plant appears to be dying. This black crusty substance is called sooty mold and is very common, especially during the summer months.

Sooty mold is caused by fungi, but there is no need to apply a fungicide since insects are the root of the problem. Sap sucking insects such as aphids, white flies, mealy bugs, and soft scale secrete a sticky shiny substance called honeydew that falls on the surface of the leaves and also on anything the is located near the affected plants including other plants, vehicles, furniture etc. The insects are usually located underneath the leaves. Sooty mold grows in the honey dew and once it covers the surface of the leaves of plants it reduces the amount of light that hits the leaf surface, thereby reducing photosynthesis and the plant’s ability to make food. The result is usually low vigor, yellow leaves, defoliation, and reduction in the quantity and quality of fruits, vegetables or blooms. If sooty mold is not controlled it could eventually kill some plants. I have personally made site visits to some homeowners whose gardenias were partially defoliated. On other occasions I have seen homeowners who are frustrated with Japanese blueberry trees covered with sooty mold, along with all of the plants underneath the trees. I highly recommend that before you place certain plants in your landscape, be aware of its pest problems. Several homeowners who have large Japanese blueberry trees told me that if they had been aware of the tree’s susceptibility to sooty mold they would not have planted the trees.

The recommendation is not to try and directly control the sooty mold but to control the above mentioned insects. The key is to detect the insect infestation when it is low which will decrease the time needed to bring it under control. Systemic insecticides such a imidacloprid or acephate, or a contact insecticide such as malathion or insecticidal soaps or horticultural oils are options to control the insects. In terms of the use of horticultural oils, you must apply and make sure you get complete coverage on the plant including underneath the leaves. A caution regarding horticultural oils, please read instructions regarding daytime temperature limits to avoid injury to plants. Once again it is very important to monitor plants weekly to insure early detection, which will lead to more effective control.

Please see picture of frost-proof gardenia which I looked at recently. These plants were showing signs of sooty mold since last year but the homeowner didn’t realize the impact of not addressing the problem. See the difference in the gardenia appearance such as fewer leaves and little or no flowers which reduces the fragrance of this Louisiana Super Plant.

Happy Gardening!!!Gerald P. Roberts

Hello Gardeners,A lot of calls have been coming into the Lafayette Parish LSU AgCenter office regarding various landscape/gardening topics and I thought I’d share them with Master Gardeners this month.

Many questions and comments address knockout roses which seem to be providing gardeners with a spectacular display of lush green foliage and gorgeous blooms. I contacted Dr. Allen Owings at the Hammond Research Station and he is witnessing the same performance from knockout roses. He feels that, because of our long winter with below average temperatures, knockout roses went through a longer and more complete rest period. When they finally came alive, they were rejuvenated. The results are seen in the foliage and flowers being more concentrated, instead of like in mild winters. Where the rest period is shorter and less complete, folage and bloom activity is spread over a longer period of time. As we say, Mother Nature did us a favor. Let us enjoy this spectacular display from reinvigorated knockout roses. Keep in mind, however, that as temperatures rise and place more stress on all roses, they will probably not look as spectacular.

On Cannas and Amaryllis, as we move into May and peak blooming declines, both will be developing seed pods. It is recommended that these seed pods be removed. Removing the seed pods allows the plant to redirect its energy to leaves and roots instead of wasting effort on seed development. Also, watch for damage from the canna leaf roller which is a caterpillar that causes brown deformed leaves and holes in the leaves of cannas. In some cases, weekly application of Orthene (acephate) will be needed to control damage from this pest.

Removing faded blooms from annuals bedding plants — commonly referred to as “deadheading” — also redirects the energy of the plants from seed development to bloom development. So to encourage extended blooming on annuals, remove blooms as they begin to fade.

The month of May is going to bring higher temperatures and cause the decline of many of our cool season annuals such as petunias, violas, pansies, and dianthus. As the temperatures progressively rise, begin making preparations to clean out these cool season annuals beds and replace them with warm season annuals such as ageratum, lantana, marigold, butterfly pentas, periwinkle, rudbeckia, salvia, dusty miller, cosmos, celosia — just to name a few. The more heat-tolerant petunias may persist into June or July, but with the more intense heat expect cool season plants to gradually decline.

If you notice the leaves of azaleas showing whitish spots or discoloration on the leaf surface, look underneath. If there are dark brown spots this indicates the presences of azalea lace bugs. This may require a couple of applications of an insecticide such as Orthene (acephate).

June bugs have been sighted for several weeks and are currently eating the foliage of several landscape plants including pecan trees. These brown beetle like bugs feed primarily at night because they remain in the soil during the day and emerges after dark. Sevin or any insecticide containing carbaryl as its active ingredient can be applied to plants being affected by June bugs/beetles just before dark, by the next morning it’s not uncommon to find these beetle bugs dead on the soil.

Buck moth caterpillars are being reported by gardeners all over Lafayette and surrounding parishes. These black caterpillars covered with spines can inflict painful stings if they come in contact with your skin while you are gardening. If you’re careful to avoid them, spraying an insecticide may not be necessary as they will be gone as soon as they complete their life cycle. However if you feel the need to control them, any common garden insecticides such a malathion, sevin, bifenthrin, cyfluthrin , will give good control.

On woody plants such as citrus, figs and many of our woody tropical plants, damage that was done by this winter’s freezing temperatures has become more evident. By now, you can look at plants and visually determine what parts of these plants can be pruned based on new growth. Brown areas can be pruned/remove up to healthy green growth.

Several callers have asked about reddish discoloration on amaryllis leaves. The reddish discoloration is cause by a fungus disease called red blotch which is common on amaryllis. According to Dan Gill, the most appropriate practice is to remove affected leaves if the infection is severe.

Finally, numerous St Augustine lawns suffered some cold damage from this past winter. Most people don’t realize that St Augustine grass is susceptible to cold damage. For this reason, recovery is going to be very important during this growing season . It is even more critical that we reduce as much stress as possible to encourage recovery. The first step, fertilization, is to provide nutrients the grass needs. According to Dr. Ron Strahan of the LSU AgCenter, St Augustine lawns should be fertilized three times annually : mid – April, mid – June, and mid – late August. If you choose to apply a water soluble fertilizer such as 13 – 13 – 13 , the rate is 7- 8 lbs per 1000 square feet for each of the three recommended applications. Another option is a slow release fertilizer such as Scotts turf builder, or any other turf fertilizer that can be purchased at garden centers or at feed and seed stores. Follow the recommended rates on the bag or package. Finally, I have seen a major improvement of many St. Augustine lawns by simply following the recommended mowing height. St Augustine lawns should be mowed at 3 – 3 ½ inches, especially in shaded or areas or when we have very hot and dry conditions. This higher mowing height reduces stress and makes for a more healthy roots system This, in turn, means a more healthy vigorous lawn that grows thicker shading out weeds, resulting in deeper roots, which also increases drought tolerance.

Happy Gardening!!!
Gerald P. Roberts

Hello Gardeners,

This month, let’s look at several topics. To most of us, the effects of this winter are not a total shock because we are aware of the unpredictable weather here in Louisiana. I’m constantly getting calls, now, from gardeners who are asking questions such as: will my gingers come back? Or, how do I determine if my angel trumpets survive? Or, how do I determine how much of my citrus trees should be pruned? The first point I’d like to make is that we are not the ones that will determine the extent of damage that occurred on landscape plants. That is going to be determined by the overall health and vigor of the plants, the plant’s (or plant group’s) degree of cold hardiness, whether or not the plants were in an exposed or protected area, and finally, how low the temperatures dropped below freezing, and how many hours temperatures remained there..

When selecting plants for our southern landscapes, gardeners should become familiar with the terms tender and hardy. Hardy plants are those that can reliably survive winter temperatures in the area where you garden with little or no protection. A plant is considered tender when it will not reliably survived winter temperatures in the area where you garden without extensive protection. Also there are various degrees of cold hardiness and cold tenderness that exist among both (hardy and tender) groups of plants. In this day and age, gardeners should be aware of the potential for damage from freezing temperatures when choosing plants for our southern gardens.
Another misunderstood term used in discussing cold temperatures during winter months is wind chill. For the record, plants don’t feel wind chill like we do; rather, plants are affected by the actual temperatures.

Upon the advice of Dan Gill and Dr. Allen Owings, both horticulturists with the LSU AgCenter, I’m telling all gardeners with the questions that I mentioned above, to be patient. Wait on Mother Nature to determine the extent of damage and the amount of pruning necessary on woody tropical plants, such as hibiscus, angel trumpet, schefflera, and whether or not herbaceous tropical plants such as cannas, elephant ears, philodendrons or gingers will sprout or put out new growth. For woody tropical plants, try scratching the bark; if the tissue is green underneath it still alive. If the tissue is tan or brown, the branch is probably dead. Start at the top and work your way down to see how far down the plant was killed. If no leaves or new growth is produced on plants or parts of plants this month, then that plant or a portion of that plant can be pruned or removed. The key is to be patient and allow the growing season to unfold before making a final determination.

Palms and their freeze injuries have also prompted many questions. We should wait until mid-to-late summer before assessing cold damage because palms will not begin to actively grow until soil temperatures rise. That is when the soil is warm and encourages the roots of palms to grow vigorously. For this reason the recommended transplanting period for palms is from late April or early May through the month of August, instead of fall and winter like other shrubs and trees.

The bottom line is that this is going to be a recovery year for a lot of tropical plants in our gardens. We must do whatever we possibly can to minimize stress on these plants. We want all the energy of the plant to be directed toward recovery, instead of battling drought or pest problems.

I’ve looked at approximately 12 lawns and had ten or more conversations with homeowners primarily concerned about their lawns being slow to green up. I pointed out to them that we have to remember that all warm season lawn grasses such as St Augustine, Centipede, Zoysia, Carpet, Bermuda require warm soil temperatures for root activity. According to Dr. Ron Strahan of the LSU AgCenter, root activity gets started when the soil temperature gets in the 60’s then progressively increases as the soil temperature rises. That is the primary reason why the recommendation for the first application of fertilizer is the 1st or 2nd week in April. In March and before daytime temperatures rises above 85 degrees, homeowners should be focusing on weed control. In early March while the soil is still cool, only very limited amounts of fertilizer will be absorbed by the roots of warm season lawn grasses. Controlling those winter weeds does a couple of things: first, it reduces the competition for water and nutrients with the lawn grass; second, it controls the weeds before they mature and drop seeds in the soil that will eventually germinate. We want to apply herbicides to control the majority of weeds before daytime temperatures surpass 85 degrees. Once temperatures rise above 85 degrees, temporary yellowing of lawn grasses can be expected with herbicide applications.

To control many of the winter broadleaf annual weeds that we currently see in lawns, there are two herbicides that are recommend at the rate of 2 ounces per gallon of water. One is Ortho Weed B Gon and the other is Fertilome Weed Freezone. Both contain the same 4 herbicides to control weeds. That is why both of these herbicides are referred to as 4-way blends for use by homeowners. Spray once; then in 10 – 14 days evaluate weeds and make another application if necessary. Either one of these herbicides will give homeowners what they need to control broadleaf weeds in warm season lawn grasses.

All lawn grasses will benefit from fertilizer applications which will provide nutrients needed for optimum performance. Some homeowners are choosing to not apply synthetic fertilizers. Instead, they are opting to leave grass clippings on the soil surface or mulching grass clippings, which return nutrients to the lawn. Other options include the application of natural or organic type lawn fertilizers. If you choose, synthetic slow-release fertilizers, those by Scott’s, Anderson’s, and Florikan are quality fertilizers that can be found locally. Water-soluble synthetic fertilizers such as 8 – 8 – 8 or 13 – 13 – 13 are also options.

Apply the fertilizer while the grass is dry, followed by rainfall or applying a sprinkler system for 15 minutes to wash the fertilizer from the lawn grass into the soil.

Finally, the best weed control is a healthy, thick, vigorous growing lawn that will keep out weeds. Mowing height makes a big contribution toward the health and performance of a lawn, with proper mowing height reducing stress on lawn grasses, especially when it is hot, dry or growing in the shade.

The following mowing heights are recommended for various warm season lawn grasses, St Augustine 3 – 3 ½ inches, Centipede 1 ½ - 2 inches, Common Bermuda 1 – 1 ½ inches, Hybrid Bermuda ¾ -1 inch and Zoysia 1 – 1 ½ inches.
Happy Gardening and Bring on Spring!

Hello Master Gardeners,
As we progressively move into Spring, many of us who love gardening realize that we have experienced an atypical winter —one like we’ve not experienced in several years. Along with numerous episodes of freezing temperatures came the challenge of trying to protect our landscape’s tropical or subtropical plants. Now that it appears that the winter of 2014 is almost behind us, we are faced with the challenge of assessing freeze damage to many of our cold-tender plants. While there are numerous issues that determine the extent of damage, we know that duration, or length of time that cold-tender plants are exposed to freezing temperatures, factors into the outcome. At one point, I can recall a local meteorologist commented that the Acadiana area had experienced around 60 hours of freezing temperatures. Anytime cold-tender plants are exposed to many hours of freezing temperatures, especially with the temperature in Lafayette dropping to 19 degrees, damage can be expected. Now comes the question of how to deal with plants that were damaged. Based on the phone calls I received within last two weeks and visits with employees at several retail garden centers, there are many people who have questions about assessing damage and what to do.

While there are a host of plants in our landscapes that will need attention following damage due to freezing temperatures, two of the most popular are citrus trees and palms. Both of these plants are susceptible to being damaged or killed by the temperatures we experienced. One of the points I’m making with gardeners regarding citrus is that kumquats and satsuma’s are the most cold hardy. Following these, in order of hardiness, are sweet oranges, with grapefruits, lemons and limes being the least cold hardy. Personal observations indicate, to me, we will lose some of these — especially younger trees that were not in a protected areas. The extent of damage is determined by several factors in addition to length of freezing temperatures: location of the plant, age, maturity and overall health of the plants. According to LSU AgCenter recommendations, it is best to wait until Spring is in “full swing” before assessing the damage to citrus. By the time we get into mid-to-late April and May, plants should show signs of new growth. We will be able to assess the damage, begin pruning off dead or brown branches and pulling out or cutting down those plants that show no signs of life. Another recommendation is to scrape the bark of branches or trunk and look for green or brown beneath the bark. Green is usually an indication of life. YET, if you want to be absolutely sure, you can wait until mid-May or a little later. One of the realities is that in South Louisiana, the limiting factor for citrus production is freezing temperatures.

In recent years, we’ve seen palms planted more frequently. There are many gardeners who are beginning to question whether or not it is wise to plant palms in our area at all. Of all the palms planted here, the queen palm has proven to be very popular. Unfortunately, it is also the least cold hardy of the palms we plant.

While all the palms suffered some damage, the vulnerable queen palms likely sustained the most damage and we should expect that some were killed. Others were damaged too and as a result will not grow out uniformly, with some of the new growth being distorted. Some palms will not recover. Palms are classified as angiosperms in the subclass monocotyledons and are more like bamboo and grasses than like other familiar trees in our landscapes. Stems or trunks of palms tend to be cylindrical in shape and usually have no leaf bearing lateral branches. There is usually one main growing point on palms known as the terminal bud located at the very top of the crown; this is where all leaves and growth arises. Once the growing point is damaged or killed—a possibility outcome with this winter’s freezing temperatures —that palm usually will not recover. Once again once that growing point is killed, the palm cannot generate a new one. That is why a palm should never be cut back from the top to try and control its height because it will die.

There are people who talked about protecting their palms by wrapping the trunks with insulating material or small Christmas tree lights; but, if nothing was done to protect the terminal bud/growing point, wrapping the trunk did little good. Since most palms are grown from seed, usually when it reaches a salable size, the grower has so much invested in the palm that it is expensive to purchase. We usually buy the larger palms; however, the larger they are the more costly they will be. So the question becomes how will we know how much damage was done or if the palm survived. For the time being, one can remove the brown fronds, but since palms don’t really begin growing until the soil temperature warms up significantly, it is recommended that a true assessment should be put off until mid-to-late summer. By that time, mother nature will show us not only the extent of damage, but whether or not a particular palm survived. As in the case of citrus, those palms that did survive will go through a process of recovery, so that means giving those plant all of the care and maintenance require to assist its recovery. Make sure they’re well watered, fertilized, and kept relatively pest free. A true assessment will have to wait until June, July or even August. Sometimes freezes will kill all the fronds, but don’t immediately assume that the palm is dead. It is always possible that the terminal bud/growing point survived. So before making a decision to remove it, wait! Give it some time, and look for new growth to occur at the center of the crown. Be aware that there have been cases where palms will begin to show new growth, then die.

Finally, when making the decision as to whether or not to plant palms, always consider the fact the even though there may have been several years of mild winters, the fact remains that it’s not a matter of “if,” but “when!” Eventually, we will, again, have temperatures similar to the ones we experienced in the winter of 2014!!!!

The sago palm is a popular plant that suffered damage and may have been lost this winter. Belonging to a group of plants called cycads, these are tropical or subtropical species that resemble palms in appearance, but that is where the similarities end. Sago palms are more closely related to pine trees. They are gymnosperms, producing seed bearing cones. Care of Sago, however, is similar to palms. For Sago palms that suffered damage, remove the brown leaves, take care of it and see if it recovers.
Happy Gardening!!!
Gerald P. Roberts

Hello Master Gardeners,

With their ability to tolerant extreme heat, moderate pest problems, tolerate a variety of soil types, and continue blooming for long periods, crape myrtles remain very popular in Southern landscapes. However in addition to their susceptibility to pest such as aphids, whiteflies, and cercospora leaf spot, it appears that there is another pest that has many horticulturist and entomologist concerned. Initial sightings of the Crape Myrtle Bark Scale was in north Dallas, Texas in 2004. The presence of this pest was confirmed in Shreveport, Louisiana, in 2012 and in Houma, Louisiana, in 2013; it has also been reported in Caddo and Bossier parishes and is suspected in Webster and Rapides, and it seems to be spreading fast. LSU AgCenter Horticulturist Allen Owings, PhD, residing at the Hammond Research Station, indicated to me that no positive identification has been confirmed in Lafayette, but it is suspected that it may already be in this parish. It shouldn’t be hard to recognize since it is the only known bark scale to occurs on crape myrtles.

At this time there are no studies to determine if some crape myrtle cultivars are more likely to be infested than others. One of the symptoms of crape myrtle bark scale is that a heavy infestation produces heavy sooty mold on the bark. Most of us are familiar with sooty mold as it occurs on citrus, gardenia, hibiscus and also on the leaves of crape myrtles. As you may recall, we’ve discussed it several times in past horticulture articles, sooty mold is a result of sucking pest such as scale, aphids, and white flies. So if we see crape myrtle showing signs of heavy sooty mold on the bark of crape myrtles, it may be this pest (crape myrtle bark scale)!!! Visually the adult female scale appears as a white or gray encrustation on small twigs and large trunks, very often occurring near wounds, or in branch crotches on older wood.

At this point control is based on limited experience with this pest and it appears that control may be difficult. One recommendations is to first wash/scrub reachable infested branches with water and liquid dishing detergent, which will remove adult females and eggs and sooty mold, making insecticide control more effective. Horticultural oil seems to be ineffective. Dormant oil applied in the winter months may be beneficial but complete coverage of the plant is essential. Only systemic insecticide is showing to be effective when applied as a soil drench over the root zone of infested crape myrtles in May and July.
    Imidacloprid is one of systemic insecticides that is recommended. Imidacloprid is the active ingredient in Bayer Advanced Garden Tree & Shrub. Additionally Greenlight Tree & Shrub with Safari is also recommended.
    I’ve already been contacted by one of our local retail nursery/garden centers requesting information from the LSU AgCenter regarding this pest. As this situation unfolds I will keep you updated as information becomes available. As Master Gardeners, you can assist the LSU AgCenter by paying close attention to pests on crape myrtles, and if you suspect an infestation of crape myrtle bark scale, please contact me so we can get a positive identification. We don’t know to what extent this pest will impact crape myrtles or how fast it will spread once it is confirmed in an area; however, I feel confident that entomologist and horticulturists in Louisiana and surrounding States are already working on result demonstrations to determine an effective means of control.

For identification purposes, pictures of the crape myrtle bark scale can be found on the University of Arkansas’s website, or if you google crape myrtle bark scale, then click on images. Several pictures of the pest will pop up for viewing.

As I come to a conclusion, we are reminded of the unpredictability of mother nature, especially as it relates to the coldest winter we’ve had in several years. Just another reminder that even though we plant tender plants in our landscapes we must always remember that sooner or later we’re going to have to give them some protection. The alternative is having them severely injured or killed by freezing temperatures. Let me remind you that several factors determine the severity of damage. The degree of cold hardiness (which depends on the plants) certainly comes to play, but also the age of the plants, health of the plant, location of the plants, and the duration of freezing temperatures.

I communicated with Dan Gill and Allen Owings and both indicated that if we did get down to 19 degrees or below in the Lafayette area, as has been projected), we can expect damage not only to many of the tropical plants , but also on palms with the most vulnerable being queen palms. At that cold temperature, citrus plants can also be expected to have some damage — but to what extent? That will not be known for several months. As Dan Gill indicated, we must not be in any hurry to prune woody type plants or palms but rather wait until April, May or even into June or July. By that time mother nature will show us the extent of the damage and after that time, we will know how much to prune or if certain plants have survived at all.

Hello Master Gardeners,

Beginning in late April and continuing through May, I receive many calls from homeowners who, when walking barefooted across their lawns, feel the pain of a winter annual weed called lawn burweed (Soliva sessilis), a member of the aster family. It is also commonly called sticker weed, spurweed and sandbur. By that time of the year, its spines have already been produced; killing the weed in late April or May will not eliminate the spines.

The LSU AgCenter recommends applying herbicides from December – March to kill the lawn burweed and eliminate production of the sharp spines. Lawn burweed is a winter annual that sprouts in the fall and winter and remains rather small during the winter months. As spring arrives with warmer temperatures, this weed goes in to a reproductive stage which begins the formation of seeds and sharp spines as it approaches maturity. As I’ve stated in the past, the best way to prevent or diminish the invasion of weeds in any lawn is to maintain a healthy lawn that out competes weeds for water, nutrients, space and light.

However if your lawn has a history of sticker weed or lawn burweed, you should be able to identify it in your lawn now. Look for a green low growing weed with leaves resembling parsley. See the picture of lawn burweed, below, taken recently in my St Augustine lawn. Applying a post emergence broadleaf herbicide when our daytime temperatures are 60 degrees or above will control this weed. Either one of two herbicides, Weed B Gon Max for Southern Lawns by Ortho or Weed Free Zone by Fertilome, will give satisfactory control. The recommendation is to make an application, wait 10 – 14 days to evaluate its effect, and make a second application if needed.

It is recommended that no applications be made on windy days and that none of the herbicide come in contact with desirable bedding plant, shrubs or trees. Both herbicides are labeled for warm season lawns. If this weed is not controlled by mid–to-late-April, the spines will already be formed and anyone walking barefoot on the lawn will experience the pain of sharp spines.

Many people call and ask me if they could apply Weed & Feed to control lawn burweed.
Dr. Ron Strahan, of the LSU AgCenter, told me that he wouldn’t recommend Weed & Feed during the winter months because it contains fertilizer. Applying fertilizer to St. Augustine grass or any other warm season lawn grass during the winter months could aggravate brown patch disease or increase susceptibility to winter injury. Any fertilizer applications should not be made until early April.

It is extremely important to follow all label directions for the mixing and application of all pesticides. Remember that the label is the law and any time you use a pesticide in a manner that is inconsistent with its label you are breaking the law.

Hoping everyone had a happy and safe holiday season and I look forward to a very productive 2014 – HAPPY GARDENING!!!

Gerald P. Roberts