Does your yard have patches of dead grass or areas that look thin and weak? The last two summers of heavy rain and the stress of December’s freezing weather have contributed to widespread outbreaks of Take-All Root Rot, a soil-inhabiting fungus Gaeumannomyces graminis var. graminis that causes yellow grass patches ranging in diameter from a few inches to more than 15 feet. The symptoms first appear in the spring, but disease can persist all summer and survive the winter. Over time the entire area dies as the root system rots away.
The pathogen is naturally present on warm-season turfgrass roots. High rainfall and stressed turfgrass trigger the disease. Because the roots are affected, they are not able to efficiently obtain water or nutrients from the soil, nor are they able to store the products of photosynthesis, which result in the loss of color in the leaves. By the time the leaf symptoms appear, the pathogen has been active on the roots for several weeks, probably longer; potentially years. If the turfgrass is not stressed, leaf symptoms may never be observed. To confirm the presence of TARR, submit a sample to the UF Pathology Lab.
This disease is very difficult to control once the above-ground symptoms are observed. Measures that prevent or alleviate stress are the best methods for controlling the disease. Any stress (environmental or man-made) placed on the turf weakens it, making it more susceptible to disease. Remember, that every maintenance practice, fertilizer application, and chemical (especially herbicide), application has an impact on turfgrass health.
Cultural practices that impact the level of stress experienced by a lawn include: proper turfgrass species selection; mowing at the correct height; irrigation timing, frequency and volume; fertilizer nitrogen and potassium sources and application quantities; thatch accumulation; and soil compaction issues. The selection of turfgrass species should be based on existing soil pH, sunlight exposure, use of the area and planned maintenance level.
Mower blades must be sharp to avoid tearing of the leaves. Additionally, turfgrasses that are cut below their optimum height become stressed and more susceptible to diseases, especially root rots. When any disease occurs, raise the cutting height. Scalping the grass damages the growing point. Raising the cutting height increases the green plant tissue available for photosynthesis, resulting in more energy for turfgrass growth and subsequent recovery from disease.
The amount of water and the timing of its application can prevent or contribute to disease development. Most fungal pathogens that cause leaf diseases require free water (rainfall, irrigation, dew) on the leaf to initiate the infection process. Irrigating every day for a few minutes is not beneficial for the turfgrass because it does not provide enough water to the root zone, but it is beneficial for turfgrass pathogens. It is always best to irrigate when dew is already present, usually between 2 and 8 a.m., and then only apply enough water to wet the root zone of the turfgrass. If an area of the lawn has an active fungus, washing or blowing off the mower following use will reduce the spread of the disease to unaffected areas.
Excessively high nitrogen fertility contributes to turfgrass diseases. The minimum amount required for the grass species should be applied. Potassium (K) is an important component in the prevention of diseases, because it prevents plant stress. Application of equal amounts of nitrogen and potassium is recommended for turfgrass health. When turfgrass roots are damaged from disease, it is beneficial to apply nutrients in a liquid solution. However, nitrate-nitrogen increases the severity of diseases, so its use should be avoided when possible. Ammonium-containing fertilizers are the preferred nitrogen sources. Heavy liming has also been linked to increases in Take-All Root Rot. Since most turfgrasses can tolerate a range of pH, maintaining soil at 5.5 to 6.0 can suppress the development of the pathogen. When the disease is active, frequent foliar applications of small amounts of nutrients is necessary to keep the turfgrass from declining.
Additional maintenance practices that need to be addressed are thatch removal and reduction of soil compaction. Excessive thatch often causes the mower tires to sink, which can result in scalping and reducing the amount of leaf tissue capable of photosynthesizing. Thatch and compacted soil prevent proper drainage, resulting in areas remaining excessively wet, depriving root systems of oxygen.
Since recovery of Take-All damaged turfgrass is often poor, complete renovation of the lawn may be necessary. Removal of all diseased tissue is advised. As a native, soil-inhabiting pathogen, Take-All-Root-Rot cannot be eliminated. But, suppression of the organism through physical removal followed by proper cultivation of the new sod is critical to the establishment of a new lawn. Turfgrass management practices, not chemicals, offer the best control of the disease.
It is acceptable to use fungicides on a preventative basis while rooting in the sod. Azoxystrobin, fenarimol, myclobutanil, propiconazole, pyraclostrobin, thiophate methyl, and triadimefon are all fungicides that can be utilized to prevent disease development while having to excessively irrigate newly laid sod. Ideally, the turf area should be mowed and irrigated prior to a fungicide application. Unless the product needs to be watered in, do not irrigate for at least 24 hours after a chemical treatment. Do not mow for at least 24 hours, to avoid removal of the product attached to the leaf blades.
Now that we have added another major stress with the recent heavy rain, it will be very important to continue monitoring the turf and being cautious about the cultural practices being used. Take-All Root Rot is likely to flourish. Do not encourage its development.
If the damaged areas are small, it may be possible to encourage turfgrass runners to grow back into the space. Application of 50/50 blends of sphagnum moss and course white sand can be used to top-dress the damage areas. Add no more than 1-inch of the mixture per application. After the stolons have crept into the voids and received a mowing, more top-dressing can be applied. Repeat until the grass stops growing in the fall. Fungicides applied in the spring and fall will help to keep the Gaeumannomyces graminis var. graminis suppressed.
Turfgrass lawns are popular. Homes and businesses alike often have at least some portion of their landscape dedicated to turf, and while it is often maligned, turfgrass does have some benefits when used and managed responsibly.
Well-managed turfgrass, like this centipedegrass lawn, can be a sustainable and attractive option for landscapes. Photo credit: Dr. J. Bryan Unruh, UF/IFAS
Detractors of lawns may argue that lawn maintenance uses water, gasoline (for mowers), and pesticides, all while contributing little to the environment. The varieties of grass we use in the Florida panhandle are not native to the area, with the possible exception of St. Augustinegrass. Planting anything – and especially non-native plants – in a monoculture limits biodiversity and does not support native wildlife. These complaints may be valid in cases, but this does not mean there is no room for turfgrass in the landscape. Instead, it is important to design landscapes appropriately and maintain lawns sustainably. The ideal of a lush, completely weed and insect free, beautifully green all year long, neatly trimmed magazine-cover style swath of grass is unrealistic.
That being said, what are lawns useful for? What are the benefits of turfgrass?
When managed properly, turfgrass can be used for numerous beneficial reasons. Grass is a plant, which means that it has roots to stabilize soil, slow runoff, and filter water. It keeps down dust, mitigates heat, and can outcompete unwanted weeds. It is useful as a surface for recreation, and can add aesthetic value to a landscape. Turf does, in fact, support wildlife to a certain degree as well, as the insects that live in and feed on it can serve as food for birds and other animals.
Improper irrigation can cause big problems with turf and lead to wasted water, but turf can help to slow down runoff and absorb excess nutrients.
Artificial turf is sometimes considered as an alternative to grass, but the differences can serve as an example of the benefits of turf. Artificial turf can heat up in the hot Florida sun. Where it is used on athletic fields, it may need to be irrigated to both cool it and keep dust down. The water used for this has much more opportunity to run off the site, as the artificial turf has no roots to slow it down. Turfgrass is also much softer than its man-made replacements; sports fields with artificial turf have a higher incidence of injury than those planted with grass.
Lawns must be managed well, however, as has been stated before. Proper species selection (whether bahia, centipede, Bermuda, St. Augustine, or Zoysia), establishment, irrigation, fertilization, and mowing practices all contribute to making turfgrass a sustainable option. You can find information on all of these in our EDIS publications, which are linked to above, or contact your local Extension office for help. If turfgrass still seems like an unpalatable option, you can also find information on turfgrass alternatives and more on Florida Friendly Landscaping. Keep your expectations reasonable and your landscapes sustainable!
Weeds are basically unwanted plants or plants growing out of place. Proper identification and some understanding of how and why weeds are present in a lawn are important when selecting the best management tactics. All turf weeds can be grouped into one of three life cycles: annual, biennial, or perennial.
Annual: Produces seeds during one season only
Biennial: Produces seeds during two back-to-back seasons
Perennial: Produces seeds over many seasons
Knowing the types of weed previously present in an area also can help one to be better prepared and what control measures to employ in the future.
Weeds may appear in multiple categories, either broadleaf, grass, or Sedges/rushes.
Winter annual weeds in lawn in early spring. Photo credit: Larry Williams
Broadleaves, or dicotyledonous plants, have two cotyledons (seed leaves) when the weed seed germinates.
Appearance: Broad, flat leaves with net-like veins and usually have showy flowers.
Common types: Clover, ground ivy, dandelions, chickweed, plantain, henbit, beggarweed.
Grasses are monocotyledonous plants that have only one cotyledon, or seed leaf, present when seedlings emerge from the soil.
Appearance: Narrow leaves with parallel veins in their true leaves. Hollow rounded stems.
Common types: crabgrass, goosegrass, crowfoot grass, bull grass, annual bluegrass, alexander grass, cogon grass, torpedo grass, and smut grass.
Sedges/rushes. Both favor a moist habitat. Appearance: triangular-shaped, solid stems, while rush stems are round and solid.
Common types: yellow and purple nutsedge and, to some degree, globe, Texas, annual, and water sedge.
One of the first steps in managing weeds is to have a healthy dense lawn/ turf to provide shade that prevents seed germination. Having a healthy lawn depends on turf species selected – making sure you put the right plant and right place. Other factors that influence a heathy turf and a reduced amount of weeds include proper cultural control, fertilizing regularly, mowing at the appropriate height, watering deeply, reducing traffic, pest control, and sanitation. If you only have a few bothersome weeds in your lawn, you may be able to dig them up by hand—but if your lawn is overrun with weeds, you may need to start from scratch. If you decide to start from the beginning, you have a choice ahead of you. Do you want to lay down seed or sod? There are pros and cons to each.
Seed
Pros: Less expensive, more variety
Cons: Takes longer to germinate, can only lay at certain times of year depending on grass type
Sod
Pros: Instant grass, can lay any time of year, requires little maintenance
Cons: More costly, less variety in grass can mean less healthy lawn overall
To prepare the soil after either method, make sure you till it down to roughly 6 to 8 inches.
Supporting information for this article can be found in the UF/IFAS EDIS publications (Weed management for Florida lawns) https://edis.ifas.ufl.edu/publication/EP141 or contact your local Extension Office!
Summer should be the time to relax and enjoy the fruit of all the hard work performed in the landscape over the previous winter and spring. However, there are still some essential tasks that need to be completed during the summer. Perform them in short energy bursts early in the morning or late in the evening.
1. Aerate Your Lawn
If your yard is starting to look weak and thin, even with fertilizing and proper moisture, it may need aeration. Aeration, which is creating channels into your lawn, allows water and nutrients to reach the deep roots of your grass more efficiently.
To test if you need to aerate your lawn, shovel up a patch of grass to a depth of at least four inches. If the layer of thatch is a half-inch thick or higher, your yard would benefit from aeration. There are self-drive aeration machines and tractor-pulled devices you can rent to make quick work of large areas. For smaller areas, simply punching multiple holes with a pitchfork will do the job.
2. Fertilize
Commercial landscape fertilizer applicators must obtain state certification.
Turf grass often displays a yellow color during the mid-summer rainy seasons due to the heavy rains flushing nitrogen away from plant roots. If your lawn is looking sad and yellow, chelated iron can often give a temporary green-up. Iron is not a replacement for nitrogen, but it can work well during our summer rainy season.
If you soil test revealed a potassium or magnesium deficiency, summer is a good time to make the last corrective application. Potassium (K) is an essential macronutrient. Fertilizer bags typically show the percentage of potassium in a product as the third number displayed on the front of the bag (e.g., the “8” in 16-2-8). Potassium acts as a “vitamin” for turf grass, increasing root strength, disease resistance and cold hardiness.
Magnesium (Mg), also a macronutrient, is essential for the production of chlorophyll, necessary for photosynthesis, and also plays a part in the movement of carbohydrates from leaves to other parts of the plant.
3. Don’t Mow Too Short
It’s a natural inclination to want to mow your grass as short as you can, so you have the longest time until you have to mow it again. However, giving your grass a buzz cut every time you mow can hurt your lawn over time.
While some turf grasses can be mowed relatively short, like Bermudas and some Zoysias, most grass types shouldn’t be cut shorter than two-and-one-half to four inches high. Mowing shorter than that can damage the growth point and leave it susceptible to disease and pest infestation. It can also dehydrate the grass and lead to long term damage.
5. Water Infrequently but Deeply
One common mistake made by many is watering too often and too shallow. When only given frequent shallow waterings, grass will begin to grow their roots upwards to take advantage of the small amounts of water, which makes weak and unhealthy. The grass becomes even more dependent on water and very susceptible to disease and insect attack.
Try watering only once or twice a week, but for a considerably longer time so that the water can penetrate deeper into the soil and encourage downward roots. Ideally, each irrigation zone is calibrated to determine the length of time it take to deliver ½ – ¾ inch. Then set the system to run every 3-4 days for that number of minutes. While checking the irrigation delivery system, make sure the rain shut-off device is working and set to the same ½ – ¾ inch.
6. Prevent Mosquitoes
Summer rains on a nearly daily basis lead to lots of standing water. In less than one inch of water, hundreds of mosquitoes can hatch 3 -5 days later. Not only are these blood-sucking pests annoying, but they can also transmit dangerous diseases like West Nile and Zika Virus. Even without disease, their bites are painful and irritating.
To prevent mosquitoes, make sure no standing water is allowed to remain in your yard, either in low points or in empty containers like flower pots or wheelbarrows. Any amount of stagnant water is the perfect breeding ground for mosquitoes. Take a walk around the yard, dumping out water and disturbing the oak and magnolia leaves that are acting a collection cup. Treat birdbaths and water features with floating “donuts” specifically designed to kill mosquito eggs.
While getting tasks done in quick morning trips to the yard, make sure to keep hydrated. Heat exhaustion can happen fast.
Dr. Bryan Unruh with robotic mower. Credit: UF/IFAS
With gas prices increasing, there are practical ways to reduce gasoline use in your own backyard.
There are electric, battery, solar powered and robotic (autonomous) lawnmowers. Do you remember the non-motorized reel mower? Or, you could use sheep. But, for the time being, most people have gasoline powered mowers. There are costs involved with mowing, including the cost of gas or diesel fuel.
Be smart as to where you grow grass. Use grass where it serves a purpose. Concentrate your efforts in growing grass where it will grow. It’s normal for lawns to decline in close proximity to large trees. As a lawn gives way to tree competition, do something else in that area. Use mulch under trees or plant shade tolerant plants.
Fertilize smart. Lawns need fertilizer. But, too much fertilizer, particularly too much nitrogen, results in excessive grass growth that requires more mowing.
Many homeowners overdo it with too much nitrogen and too little potassium. Fertilizers with the correct ratios of nitrogen to potassium will produce the right balance of shoot to root growth. Choose a fertilizer such as 15-0-15 or some similar analysis with some slow release nitrogen. Fertilize to produce adequate growth and the correct color. If your lawn is a healthy green and you’re mowing, mowing, mowing… why add more fertilizer?
Centipedegrass and bahiagrass will grow best with fewer problems when fertilized sparingly. This would be one or two light applications of fertilizer per year, or none at all if these grasses are performing well. St. Augustinegrass and zoysiagrass might get by on one spring application; however, it’s more common to apply a second time during summer.
Never apply more than the recommended amount of fertilizer per application. You can always split the total amount into two or more applications, which will produce more even growth and minimize sudden growth spurts.
Though it’s a popular practice, reconsider overseeding your lawn with ryegrass this fall. Weigh the desire to have a green lawn through winter with the extra time and costs (gas, fertilizer, water and pesticides) involved with maintaining it.
Finally, keep your gas-powered lawnmower in good working condition. It can make a difference in how efficiently it operates. Make sure the equipment is clean. Change the oil if needed. Replace or clean the air filter and spark plug. Keep lawnmower blades sharp. Basically, follow the owner’s manual for routine maintenance.
Implementing these ideas can help conserve fuel and result in a healthier lawn.
Hot, summer months are not the time to be using most lawn herbicides.
One issue is the heat of summer. Most lawn herbicide labels include statements such as the following.
“Do not apply when temperature exceeds 90°F.” “Do not broadcast apply this product when air temperatures are above 90°F (85°F for St. Augustinegrass) unless temporary turf injury can be tolerated.”
Every year we’ll see lawns that are injured or killed because of lawn herbicides being applied when temperatures are too hot.
Summer is usually a rainy and windy time of the year. Many lawn herbicide labels include statements such as the following.
“Allow 12 hours after application before watering lawn for maximum effectives on listed weeds.” “Apply only when wind is no more than 10 mph.” “Applying this product in calm weather when rain is not predicted for the next 24 hours will help to ensure that wind or rain does not blow or wash pesticide off the treatment area.”
It is critical to read and follow the label directions and precautions for any pesticide you use. Pesticide labels, including herbicides, include the following statements.
“To the extent consistent with applicable law, the buyer assumes all risks of use, storage, or handling of this product not in accordance with label directions.” “It is a violation of Federal law to use this product in a manner inconsistent with its labeling.”
Crabgrass growing in centipedegrass lawn. Photo credit: UF/IFAS Extension
By the time summer arrives, many of the lawn weeds are mature, which means they are well established with extensive root systems. These mature, well established weeds are much more difficult to control. They are more susceptible to herbicides when they are small, young, and not well established. Also, these mature weeds have been allowed to produce countless numbers of seeds as they move into summer. Most weeds are prolific seed producers. For example, a single crabgrass plant (a common summer lawn weed) can produce 150,000 seeds.
Applying a preemergence lawn herbicide in February to help prevent summer annual weeds such as crabgrass or applying a postemergence lawn herbicide during spring while the weather is mild and before the weeds are out of control simply makes more sense than waiting until summer.
The best options now with lawn weed control involve continuing to follow good mowing practices, maybe hand removal of some weeds, and just simply waiting it out until next February and spring to worry with the use of lawn herbicides.
In the meantime, you may want to read the following UF/IFAS Extension publication on lawn weed control.
