by Sheila Dunning | May 13, 2014
Last summer’s heavy rain and the stress of January’s icy 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.
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. 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.
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 saturate the root zone of the turfgrass.
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 their 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 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.
by Julie McConnell | May 3, 2014
The last week of April 2014 brought with it 10-22 inches of rain across the panhandle in a matter of days. Some areas had immediate flooding and standing water, while others may be in areas at risk of rising rivers and streams. As the water recedes, many people are wondering how all the water will affect their landscapes.
Only time will tell what the long term impact will be, but here are a few things to watch for and what you can do to try to moderate damage.
- Let soils dry out before driving vehicles or other equipment on grassy areas. Even if the water is not visible, if the soil is still saturated, driving lawn equipment or cars may cause ruts.
- Do not leave automatic irrigation systems running on established shrubs, trees, and lawns. If your system is set to run in the early morning hours, you may not think about it being on, check your systems and hold off on adding water until soils dry out and the plants need it.
- Watch for fungus symptoms and treat if needed. Wet plants and cool weather are ideal for some Brown Patch on lawns, be aware and monitor landscapes closely. If disease is suspected, contact your local county extension office for recommendation.
- When mowing, leave a longer leaf blade to compensate for root stress.
- Look at the base of trees and shrubs to make sure silt and sand have not buried the crown or root flare. Also look for erosion of root zone, these areas may need correction. “Salvaging Flood-Damaged Shrubs and Ornamentals.”
- Adjust fertilization as needed; if you recently applied fertilizer it has likely runoff or leached from the site. However, if you suspect fungal disease do not fertilize until disease is managed.
- Stress in turfgrass, for details read “Watch Turf for Flooding Stress”
- You may see new weeds (seeds or segments may have washed or blown into your yard)
- Tree and shrub decline or death read “We Had Plenty of Rain, Why are My Trees Dying?”
- Although this storm was not a hurricane, “Assessing Damage and Restoring Trees After a Hurricane” has helpful information for areas with wind damage
- Nutritional deficiency symptoms in palms may show up 4-5 months from now. “Nutrient Deficiencies of Landscape and Field-grown Palms in Florida.”
- Decreased availability and increased price of sod (flooded fields prevent harvest and increase inputs for disease, weed, and nutrition management)
- Scheduling changes or maintenance adjustments by landscape contractors. Turfgrass and ornamentals will likely need different maintenance applications than in years past to correct issues related to flooding and excess rain.
by Carrie Stevenson | Oct 7, 2013
After severe weather of any kind, homeowners must often spend a considerable amount of time dealing with impacts to their landscapes. Below are a few lessons we have learned from hurricanes and tropical storms in the past. Many thanks to fellow agent Beth Bolles for her contributions to this article.
Dealing with Toppled Trees
It may be difficult to turn an uprooted favorite tree into firewood, but this is probably the best choice. A small or young tree may be replanted successfully if done immediately. These trees will require bracing for up to two years until the root systems regrow and are able to support themselves. If the roots have been exposed for an extended period of time, don’t try and save the tree. Exposed roots should be covered with soil or moist burlap for protection from drying out. Large or older trees will typically not survive this ordeal even with the best of care. Because the root system is compromised, attempting to keep the tree may create a hazard down the road with the next storm.
If a tree is completely uprooted, its odds of recovery are severely limited and it is best to remove the tree. Photo courtesy Beth Bolles, UF IFAS Extension
When removing fallen trees, think ahead about whether you plan to remove stumps. It’s a lot easier to pull instead of dig stumps out of the ground, so leave a four-foot stump to make your life easier. Be careful using power equipment like chain saws. It may be better to hire a professional to deal with removing large trees, especially around power lines.
Exposed Roots or Leaning Trees
Any exposed roots should be covered immediately. Cover roots with nearby soil at the same level roots were originally growing. Do not bank the soil higher because this will cut off oxygen supplies to roots in an already oxygen deprived, saturated soil.
If small trees are leaning and need straightening, they can be staked and treated like a newly planted tree. Larger trees with trunks greater than six inches in diameter can be saved but should be removed if they are a hazard to structures, power lines, or roadways. Reset the trees with stakes or guy wires for support. Trees with trunks measuring less than two inches in diameter can be supported with two or three forty-eight inch, two inch by two inch wood stakes placed one foot outside of the root ball inserted eighteen inches into the ground. Larger trees should be anchored with three or four guy wires or cables. Cover guy wires that are in contact with the trunk with rubber hoses to prevent damage.
A leaning, partially uprooted tree may recover if it is righted and its roots are covered back with soil. Photo courtesty Beth Bolles, UF IFAS Extension
Replace the soil around the area and firm to assure there are no air pockets around the roots. Make sure the top root coming off the trunk is level with the existing soil. If many trees were swaying back and forth during the wind, there may be air pockets underneath the trees. If this is obvious, add soil and water to eliminate any air pockets. If root damage is obvious, do not fertilize at this time because salts in the fertilizer may damage new feeder roots.
Broken Branches
Broken branches should be removed from trees and shrubs as soon as possible to prevent tearing into trunk wood. Make clean cuts just outside of the branch collar to avoid damaging the trunk. If these are large branches, make three separate cuts to prevent tearing. Make the first cut on the underside of the branch about fifteen inches from the trunk and one-third through the branch. The second cut is made from the top, a few inches out from the first cut. This cut should remove the weight of the branch so the next one will not rip the trunk. The remaining stub can be held while the last cut is made. Make the last cut just outside the branch bark ridge and end outside the trunk collar (swollen area on lower side of branch). This is not a flush cut with the trunk and should leave a small protrusion on the trunk. Do not use wound dressing on the cut surface, as this practice is no longer recommended.
If trees lost all of their branches, it is advisable to remove the tree. The natural shape is gone and trees like pines will typically not recover. Some trees may lose the majority of their leaves, but these will flush back out so they should be okay.
Repairing Lawns
Keep a close eye on lawns for disease problems due to all the rain. Brown patch and take-all root rot would be the major concerns. Rake and remove all debris to give lawns a chance to dry out. If lawn areas are damaged, now is the time to replace with plugs or sod so they can establish before winter. Sod webworms are bad now so don’t mistake this damage for diseases. If adult moths are obvious and grass blades are closely cropped, this is due to caterpillar damage…not disease.
Watering
Most soils are saturated and irrigation systems should be in the off-mode. If there is standing water around trees or in other low areas, use a hose to siphon water to a retention pond or a better-drained area. Once soils dry out and the sun comes out, keep a close eye on plants as they may require more frequent irrigation because of root damage. Coastal areas flooded with saltwater may experience damage from extended exposure to high salinity; it is recommended to run a sprinkler system to flush out a lawn after the water retreats.
If you have questions, contact your local UF IFAS Extension Office!
by Carrie Stevenson | Sep 2, 2013
One of the natural phenomena I’ve loved watching this rainy summer is the dramatic “life and death” cycle of the resurrection fern (Pleopeltis polypodioides). Found most often along the branches and trunks of stately mature live oaks, this plant turns from a dry, crackly brown to a vibrant green in the span of a day.
Dry, brown resurrection fern on a live oak after a period without rain. Photo credit: Carrie Stevenson
Like Spanish moss this epiphyte, or “air plant”, uses a host plant (live oak, pecan, or sabal palm) as its growing surface. Yet the fern does not damage the tree. Its root system is composed of long, winding rhizomes that tuck into the nooks and crannies of the tree’s bark, collecting rainwater and nutrients from airborne dust and nutrients leaching from the trees themselves.
The fern’s unusual response to dry weather is an adaptation that allows the fronds to curl inward, reducing water loss by decreasing surface area exposed to the elements.
Blades of turf-grass will respond similarly to drought, folding in half after several days with no water. However, the resurrection fern takes drought tolerance to a whole new level, capable of losing up to 97% of its water content without dying. As a comparison, most plants will start to die back at a 10% water loss. Several researchers estimate the fern can live 100 years in its dry state. However, true to its name, the resurrection fern will spring back to life after a rain or an increase in humidity.
The fern that was completely dry one day will turn a vibrant green just after a rainfall. Photo credit: Carrie Stevenson
The resurrection fern has earned its place in history for several other reasons. According to literature from early pioneers and indigenous people, members of the Florida Seminole and Miccosukee tribes used the fern in baths to treat insanity. They also made a root mixture of the resurrection fern and Shoestring fern (Vittaria lineata) to treat chronic health conditions and sick babies.
Because of its unique attributes, resurrection ferns were taken in space along with the shuttle Discovery in 1997 as part of a mission to better understand natural phenomena from the perspective of space.
The thin, elongated rhizomes of the resurrection fern root into the crevices of a live oak’s bark. Photo credit: Carrie Stevenson
The plant is native to the eastern United States west to Texas and throughout the American tropics. A variety of the species is also native to southern Africa. It can be propagated by cutting several inches of the rhizomes and placing them into crevices of another tree, log, or rocky area. Dry fronds will respond to being sprayed with water in under an hour, so it’s also a fun experiment to show kids!
For more on resurrection ferns, check out the UF School of Forest Resources.
by Larry Williams | Jul 22, 2013
Gray Leaf Spot is a common fungal disease of St. Augustinegrass. Recent wet conditions have promoted this disease. This includes high humidity, heavy dews and particularly frequent afternoon and evening rains.
Gray leaf spot symptoms on St. Augustinegrass. Photo credit: UF/IFAS Extension
The individual spots or lesions are first seen as tiny brownish spots smaller than a pinhead. As they become larger, they will be circular and then begin to elongate lengthwise along the leaf. The spots will become brown to grayish in appearance. Numerous spots or lesions may be found on an individual leaf. Heavily infected leaves begin to turn brown and wither, usually beginning at the tip of the blade.
Gray leaf spot can move rapidly during prolonged warm, wet periods. Over watering or irrigating in the evening provides the prolonged period of wetness required for disease infection. For more information on how to correctly water a Florida lawn, visit the UF / IFAS Lawn Watering Website.
According to the Florida Lawn Handbook, “Severity of the disease is enhanced by application of readily available nitrogen fertilizer and is proportional to the amount of nitrogen applied.” Select fertilizers that are low in nitrogen or that have slow release nitrogen. Be careful to not overdo it in fertilizing your lawn and do not apply a high nitrogen fertilizer on top of an already infected lawn. Also, some lawn weed killers such as atrazine will increase the susceptibility of the grass to gray leaf spot.
Irrigate during early morning hours to minimize the period in which the grass is wet and water only on an as needed basis, watering less often but deeply. Avoid frequent, shallow watering and don’t irrigate when the lawn is already wet from rain. With the recent frequent rains, very little to no supplemental irrigation has been needed on most lawns in our area. Avoid leaving irrigation timers on when adequate rainfall has occurred. It’s best to operate irrigation controllers on manual so that the lawn can be monitored and irrigation provided during dry times.
If the disease outbreak is severe, fungicide may be needed. Look for products containing propiconazole, triadimefon or thiophanate-methyl. Always follow the product’s label directions and precautions.
For more information on maintaining a Florida lawn, contact your County UF/IFAS Extension Office or visit the YourFloridaLawn Website.
by Carrie Stevenson | Jul 7, 2013
Floridians use more water than any other state for irrigation, and a typical home sprinkler system can account for half of the cost and water use in a household during the summer.
One of the most convenient and efficient ways to conserve water is to install a rain barrel. Modern rain barrels involve ancient technology that relies simply on gravity, allowing stormwater to run from a rooftop into a gutter. The gutter funnels water into a plastic food-grade barrel or other container fitted with screen to keep out debris and insects. Most rain barrels also have an overflow device near the top (for heavy storms that might fill the barrel) and a spigot at the bottom for filling a watering can or attaching a hose. Keep in mind the barrels do not have a lot of pressure and cannot irrigate an entire lawn, but are ideal for vegetable gardens and container plants. Rain barrels vary widely in design, but they can be painted to add a decorative touch, or easily screened behind a shrub.
Building a rain barrel is a fun summer project for the whole family!
In addition to conserving water, rain barrels can be an effective means of reducing stormwater pollution. During a typical 1” rainstorm, an average home’s roof can yield 600 gallons of rainwater runoff that would normally flow downstream, picking up oils, greases, bacteria, trash, and pesticides along the way that end up in our water bodies. These pollutants eventually flow downstream to our creeks, bayous, and bays, contributing to non-point source pollution. Rain barrels interrupt that process by collecting stormwater runoff before it has a chance to pick up pollutants.
If you are interested in learning more about rain barrels or how to build your own, contact your local County Extension Office. Escambia County Extension will be hosting two rain barrel workshops this summer, the first on Friday, July 12 and the second on Saturday, August 3. There is a $42 charge for those wishing to build their own rain barrel after the workshop—all supplies and tools will be provided. To register for the full workshop, go online to the event registration website.
It is free to attend and hear the talk without building a barrel, but please reserve a spot by using the contact information below.
