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Tall Fescue

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Biology: Tall Fescue (Festuca arundinacea) is perennial grass that can be both desirable as a lawn species when using improved cultivars or undesirable when forage-type (wide-bladed) tall fescue plants a contaminant other primary species in a lawn.

For all of you nerds out there like me, you might be interested in know that there has been much recent debate about the scientific name of tall fescue. While tall fescue has used the above scientific name consistently for over 60 years, it is now being classified by scientists formally as Schedonorus arundinaceus (Schreb.) Dumort. (also = Lolium arundinaceum (Schreb.) S.J. Darbyshire; formerly = Festuca arundinacea Schreb.). I know, very confusing even for me. Remember that there are many grasses called “fescues”. I wrote about this in a previous turf tip that I would encourage you to read (click here).

Identification: Tall fescue is a coarse-textured (wide-bladed), bunch-type grass. Improvements in tall fescue leaf texture have resulted in more fine-bladed varieties/cultivars that have helped to increase the turf quality and use of this drought-tolerant turf in Indiana. We often recommend improved turf-type varieties of tall fescue as the primary species for lawns, but older, wider-bladed, forage-type varieties of tall fescue such as Kentucky 31 (KY-31) still exist, and can be problematic weeds in lawns. This forage-type tall fescue can be easily spotted in lawns in early spring when they green-up faster than Kentucky bluegrass and by its bunch-type growth habit, which results in a clump of turf when present as a weed. Also, forage-type tall fescue can be easily spotted in lawns during drought as tall fescue stays green and actively growing during drought whereas Kentucky bluegrass will often enter a drought-induced summer dormancy.

Kentucky 31 (KY-31) tall fescue makes a poor lawn.
Improved “turf-type” tall fescue
Sometimes tall fescue blends well into your lawn. Notice tall fescue clump in center of photo.
Weedy, forage tall fescue clumps are easily visible in Kentucky bluegrass turf in early spring.
Tall fescue in bermudagrass turf in the spring during green-up.
Tall fescue (green clumps) in a Kentucky bluegrass turf during a summer drought.

Tall fescue will often lack a ligule or possibly have a short membranous ligule.

A very short ligule is barely visible.

Auricles are usually short and blunt but some can also be classified as short-clasping meaning that the auricle may wrap-around the stem but may not fully clasp or cross one another. You may also see small hairs protruding from the auricle.

See the short auricle and small hairs?

The vernation (how the leaf is oriented inside the stem) is rolled on tall fescue and the collar is conspicuous (obvious) and usually wide.

Broad collar is easily visible.
Broad collar is easily visible.

The leaf blade is wide but variable in length with a pointed leaf tip. In some cases you can actually feel little barbs along the leaf margin when you run your fingers from the leaf tip down the leaf blade.One last helpful identification is the prominent veins in tall fescue compared to Kentucky bluegrass (only midrib is clearly visible).

For more on tall fescue identification, see this page in our turfgrass identification tool (click here, requires flash player).
Cultural control: When there are few weedy patches of bunch-type grasses like tall fescue, it is best to cut them out with a shovel or knife. Be sure to cut down a couple of inches into the soil to get all the stems. Refill the holes with soil and seed immediately with the desirable turf species similar to the existing turf.
Biological control: None known.

Chemical control: If the area has a large number of tall fescue plants, chemical control will be more efficient. A nonselective herbicide such as glyphosate (Roundup and others) can be spot-applied. These herbicides will also kill the surrounding desired turf species, so be careful to treat only the clump of tall fescue. Two applications may be needed for complete control and the area should be reseeded 7 to 14-days after the final application. Thoroughly rake the area to be seeded to remove dead plant material and ensure good seed-soil contact. For more information about complete renovation, refer to Turfgrass Renovation (Purdue Extension publication AY-13-W).

Chlorsulfuron (Corsair) was a selective herbicide registered for the control of tall fescue in many turf species. Some quantities of Corsair (labeled for most major turf areas) may still exist but this herbicide is no longer sold. Telar XP and Chlorsulfuron 75DF contain the same ingredient as Corsiar and can be used on turf in industrial sites and roadsides but not in managed turf areas like golf courses, lawns, and athletic fields. Spot apply chlorsulfuron according to label instructions. The tall fescue will slowly thin and die, allowing the desired species to fill in. Reseeding should not be needed if Kentucky bluegrass is present. Chlorsulfuron will kill perennial ryegrass, so do not apply it to perennial ryegrass.

To control tall fescue in warm-season lawns and athletic fields, apply a nonselective herbicide like glyphosate in late winter while bermudagrass is dormant. Alternatively, many sulfonylurea herbicides are labeled for the selective removal of cool-season grasses such as tall fescue from bermudagrass and zoysiagrass.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

For archives of past weed of the month postings, visit our Weed of the Month Archive.

Aaron Patton, Turfgrass Extension Specialist

White Clover

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Biology: White clover (Trifolium repens) is a perennial broadleaf weed that can be found throughout the United States. Seeds can germinate in moist-cool conditions in spring, early summer, or early fall. Because it tolerates close mowing, can grow in multiple soil types, and has the ability to fix its own nitrogen, it competes with the surrounding turf. As a result, white clover is a common occurrence in lawns and other high-maintenance turf throughout the state of Indiana.

Some view white clover as a weed – hence it’s appearance in this weed of the month series – while others view white clover as an important component of the turf which provides beneficial nitrogen contributions to the soil. Current research efforts at Purdue led by Dr. Cale Bigelow and his graduate student Gabe Macke are focused on learning more about the potential benefits of grass-clover systems and the challenges in maintaining these mixed swards. More information about white clover management (both control and culture) will continue to be provided as we learn more.

 
Identification: White clover forms mat-like patches in lawns as it spreads via low-creeping stolons that can grow at a rate of 18 cm per year. Stems can be smooth or sparsely covered with hairs. Leaves are generally arranged in threes; however, occasionally the appearance of 4 leaves can give white clover a ‘shamrock’ or a ‘4-leaf clover’ appearance. Leaves are predominantly egg-shaped, grayish-green on the bottom, and bright-green on top with a distinctive gray-green splotch or watermark at the base. Flowers are white, often with pink tinge, and are arranged in aggregated, rounded heads that can hold up to 85 flowers. Seed coats are extremely hard, thus allowing for extended dormancy periods in the soil. Other trifoliolate (3 leaves) legumes, such as red clover, are similar but generally larger in size, have more pubescent stems, and more elongated leaflets than white clover.
 
Rounded flower clusters can hole up to 85 flowers.
Pink tinge at the base of white flower petals.
Trifoliate (3-leaf) arrangement with distinctive watermark.
Appearance of 4 leaves produce a ‘shamrock’ or ‘4-leaf clover’ appearance.
White clover in closely mown turf.
Presence of white clover may be an indication of low nitrogen fertility.
Large patches of white clover in dormant bermudgrass turf.
Large patch of dense, mat-like growth.
Cultural control: The use of cultural practices, such as increased mowing height, adequate irrigation, and overseeding to enhance cool-season turf density and vigor may help the lawn to out compete white clover infestations. Since white clover is a legume capable of fixing its own nitrogen, adequate nitrogen fertilization will often help to reduce clover and further develop a more competitive turf.
 
Biological control: None known for specific use in white clover. There are some organic postemergence herbicides available for turf weed control. For example, pelargonic acid (Scythe) and acetic acid (5% or greater solutions) may be used to manage weeds. Other products such as Eugenol, which contain medium-length fatty acids and clove oil, have shown some promise as an effective weed control tool. However, these organic herbicides do not differentiate between the target weed and the desired turf (non-selective) and should only be applied as spot treatments in direct contact with the weed only. As a result, most of these organic herbicides have limited use in turf and are better suited for weed control in parking lots, along fence rows, and in other bare-ground areas.

 

Many new organic products contain essential micronutrients, such as iron HEDTA (FeHEDTA) as the active ingredient. Though multiple applications of these products are required, turf injury is generally decreased (can actually make the turf darker); however, their ability to provide long-term weed control is not well-documented.

 
Chemical control: Chemical management of white clover is generally focused on a postemergence strategy over a preemergence strategy because of the few preemergence herbicides available for broadleaf weeds in cool-season turf and because white clover may germinate at different times throughout the year. The best selective herbicide management strategy is repeat applications of two- or three-way mixtures of 2,4-D, dicamba, MCPP. Products that contain one or more of the following ingredients should also provide effective control in cool-season turf: clopyralid, dicamba, florasulam, MCPP, and quinclorac. 
 
 
For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

 

For archives of past weed of the month postings, visit our Weed of the Month Archive.

Aaron Patton, Turfgrass Extension Specialist
Leslie Beck, Postdoctoral Research Associate
 

Wild Garlic

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Biology: Wild Garlic (Allium vineale) is a monocotyledonous cool-season perennial that can be found throughout most of the eastern and southern United States. Despite having linear leaves and parallel veins, wild garlic is neither a grass nor a sedge; it is a member of the lily family. Wild garlic is more noticeable in the winter months when the turf is not actively growing or being mown. Plants reproduce from seeds and aerial bulbets from early spring and throughout the summer months. Its ability to tolerate a wide range of soil types, and to survive mowing height typical of lawns make wild garlic a difficult-to-control weed in cool-season turf.

Identification: Wild garlic is a bulbous perennial with grass-like leaves that emerges in turf in the early spring. Leaves are slender, rounded, and hollow. Wild garlic is often mistaken for wild onion; however, wild onion leaves are more flattened and are not hollow. Wild garlic leaves have a distinct garlic-like odor when crushed or mown. Leaves emerge from an underground white bulb with a papery outer coating, which also gives rise to multiple bulbets that are flattened on one side and also covered by a papery-like membrane. Greenish-white ‘flowers’ can be observed atop short flowering stems in late spring through early summer. In the place of flowers, small globe-shaped aerial bulbets are produced that are greenish-white and have long tail-like green leaves. Wild garlic plants may die back in the summer, but leafless stalks bearing viable seed capsules may remain.

Wild garlic’s grass-like growth in dormant turf

Hollow stems

Aerial bulbet

Wild garlic clumps in dormant turf

At times, wild garlic leaves can appear curved or curled

 

Cultural control: Proper turf maintenance such as adequate mowing height, fertilization, and irrigation to develop a dense, aggressive turf leading into the winter months may help to manage wild garlic. Hand-pulling wild garlic is generally not an effective method of weed control since hollow stems are easily broken leaving the bulb below the soil to generate new leaves and new bulbets. As a result, bulbs need to be dug-up in order to achieve an adequate level of control.

Biological control: None known for specific use in wild garlic.

Chemical control: In cool-season turf, wild garlic is difficult to control. There are no preemergence herbicide options for wild garlic in cool-season turf; however, there are a few postemergence herbicide options. Applications of 2,4-D alone or in multiple combinations with MCPP and dicamba (Trimec, Triplet, etc.) may achieve fair levels of control. The ester formulations of 2,4-D are more effective against wild garlic than the amine formulations (consult the Purdue Turfgrass Weed Control for Professionals extension publication (link below) for more information regarding the differences between amine and ester 2,4-D formulations). Additionally, mowing the weeded area prior to application may improve herbicide uptake and overall control of wild garlic in cool-season turf.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

For archives of past weed of the month postings, visit our Weed of the Month Archive.

Aaron Patton, Turfgrass Extension Specialist
Leslie Beck, Postdoctoral Research Associate

Wild Violets

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Biology: Collectively, turf managers refer to the Midwest species common blue violet (Viola sororia), wooly blue violet (Viola papilionacea), and confederate violet (Viola sororia f. priceana) all as wild violet. Additionally, yellow violet (Viola pubescens) is also found in Indiana. Wild violets are a persistent, perennial, and difficult-to-control broadleaf plant. It is regarded as a desirable perennial plant by some as well as a weed by others.

Common blue violet.

Wild violets in a shady lawn.

Wild violet leaf.

Identification: Violets can be identified by their heart shaped leaves which are pointed at their tip and have rounded teeth on their margins. Violets spread by short rhizomes and by seed. Short rhizomes about the size of your “pinky” finger are common to all Indiana wild violet species. Wild violets are typically found in shady areas with moist soil but they can also grow in sunny, droughty areas.

Wild violet rhizome on soil surface.

Wild violet plant showing rhizome after washing off soil.

Flower color varies by species. Common blue and wooly blue violets (both have a purple, blue, violet color. Confederate violet has white petals with an inner violet color. Yellow violet has a yellow color.

Common blue violet. Wooly blue violets have the same flower color.

Confederate violet.

The confederate violet and common blue violet are often found in the same area.

Yellow violet.

Following flowering and pollination, fruit capsules form. Seed is dispersed from the capsules by gravity after the capsules dry.

Seed capsules.

Seed capsules after drying showing the dark-colored seeds.

Cultural control: Cultural practices such as proper mowing, fertilization, and irrigation can be manipulated to control some weed species but these practices have little impact on wild violet populations in lawns. Wild violet can be decreased by more frequent mowing but not by fertilization. It is unknown how irrigation, drainage, and soil compaction influence wild violet populations. As such, turf managers rely on herbicides to control wild violet.

If you wish to increase wild violets in your lawn, simply reduce your lawns nitrogen fertilization and maintain moderate to high levels of shade by withholding pruning of trees.

Biological control: Some organic herbicides are available. Among the postemergence organic herbicides, the most common are pelargonic acid (Scythe) and acetic acid (5 percent or greater solutions). Other products that contain medium-length fatty acids and clove oil (eugenol) show some promise; however, these organic postemergence herbicides are nonselective and can injure actively growing desirable plants in the lawn and landscape, so their use should be limited to directed spot treatments. The bottom line is that most organic postemergence herbicides have limited use in turf and are better suited to weed control in parking lots, fence rows, and other bare ground applications. Many new organic products contain the active ingredient iron HEDTA (FeHEDTA). Multiple applications of this product are required for control. FeHEDTA containing products injure turf less (can actually make turf darker green), but their efficacy for weed control is yet to be well documented.

Chemical control: Good chemical control of wild violet is typically obtained with triclopyr (Turflon Ester Ultra or Triclopyr 4). Many herbicides are available with triclopyr as the key ingredient (see Commonly Used Broadleaf Herbicide Combinations for Turfgrass, page 62). For best control with triclopyr use more than 0.5 lb ai/A. Turflon Ester Ultra and Triclopyr 4 at 1 pt/A will deliver 0.5 lb ai/A; and at 1 qt/A will deliver 1.0 lb ai/A. Chaser, Chaser 2 amine, Confront, 2-D, and Tailspin will also deliver ≥0.5 lb ai/A.

For more information on weed control, search this blog and archived turf tip postings and check out our Turfgrass Weed Control for Professionals Publication.

Aaron Patton, Turfgrass Extension Specialist

Yellow Nutsedge

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Biology: Yellow nutsedge (Cyperus esculentus), also known as chufa (chufa is a non-weedy variety that is used for wildlife food plots and is not a cold hardy weed like yellow nutsedge), nutgrass, or watergrass, is a troublesome, difficult-to-control perennial weed found throughout the United States. It is important to understand that yellow nutsedge is not a grass or a broadleaf weed, but a sedge; which is crucial when determining effective control strategies. It establishes by rhizomes, which form tubers (called nutlets) that are capable of surviving in the soil for periods of up to ten years. These nutlets, as well as viable seed, sprout and establish from May until the end of July. The ability of nutlets to survive long periods in the soil and the mature plant to withstand frequent, low mowing practices, make yellow nutsedge a difficult-to-control weed in turf.

 
Identification: Yellow nutsedge is most noticeable in the summer during periods of high temperatures and drought because its leaves grow more rapidly than the surrounding turf. Yellow nutsedge can be identified by solid, triangular-shaped stems which are be easily determined by rolling the stem back and forth between fingertips. Yellow nutsedge leaves have a prominent mid-rib and are arranged in threes which also help to distinguish it from grasses. Leaves are a light green to yellowish in color, have a shiny/waxy appearance, and have a long leaf-tip tapered to a sharp point. While many grasses have hairs on the leaf blades, such as crabgrass or bermudagrass, yellow nutsedge leaves and stems are completely smooth, which accentuates the shininess of the leaves. Though it seldom forms in areas of mowed turf, yellow nutsedge produces golden to brown colored seedheads (short spikelets) from July to September. It is often mistaken for purple nutsedge; however, purple nutsedge has dark green leaves that quickly taper to a blunter tip, and produces reddish brown to purple seedheads (spikelets). Additionally, purple nutsedge develops tubers along the entire length of rhizomes where yellow nutsedge only produces tubers at rhizome tips.  
 

 

Yellow nutsedge grows more quickly than the surrounding cool-season turf during high temperatures
Purple nutsedge (left) leaf tip compared to yellow nutsedge (right) leaf tip
Growth habit is a 3-leaf arrangement
Cross-cut shows solid triangle-shaped stem
Establishes by rhizomes beneath the soil surface
Nutlets formed (top) and forming (bottom). Photo credit, Corey Gerber.
Light golden/brown seedhead
Yellow nutsedge leaves have a distinct waxy/shiny appearance in cool-season turf
Presence can indicate poorly-drained or compacted areas where surrounding turf struggles
More problematic on turf that is mowed to short or in areas of poor drainage such as low areas in the golf course fairways (above).

Cultural control: The best method of cultural control is a dense, aggressive turf that can successfully outcompete invading weeds for nutrients and space. Yellow nutsedge is more problematic on turf that is mown too short and thrives in areas where the soil is constantly moist from over-watering or poor irrigation drainage. Cultural practices such as increasing mowing height, watering deeply and infrequently, and cultivation (aeration) to alleviate soil compaction may help to maintain yellow nutsedge. If populations are small enough, hand-pulling will help to remove the above-ground-tissue; however, within a few weeks the plant will most likely grow back from the underground tubers. When yellow nutsedge is located in a landscape system, it is best to try and dig-out the entire plant (including the root/rhizome underground system) for more prolonged eradication.

Biological control: None known for specific use in yellow nutsedge.

Chemical control: Yellow nutsedge is a difficult-to-control weed that may require multiple herbicide applications. Purdue extension offers many publications about establishing, maintaining, and controlling lawn pests such as weeds. This information is available at The Purdue Extension Education Store or The Purdue Turf Program website. For yellow nutsedge herbicide control options for homeowners refer to publication AY-19-W, and for turf professionals refer to publication AY-338-W. Both publications are free for electronic download.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

For archives of past weed of the month postings, visit our Weed of the Month Archive.

Aaron Patton, Turfgrass Extension Specialist

Leslie Beck, Postdoctoral Research Associate

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