Grassy Weeds

Tall fescue is a clumping perennial cool-season turfgrass. Its coarse texture and aggressive growth habit make it objectionable in many situations because it does not mix well with other turfs.  As with most perennial grasses, it is very difficult to remove tall fescue by cultural means. Standard recommendations for increased fertility and mowing frequency will only serve to improve the quality of the tall fescue as well as the surrounding turf. Physical removal of patches by hand/shovel is the most effective technique for eliminating tall fescue.  Tall Fescue is most obvious during the spring and during drought conditions. and can be easily confused with crabgrass. 

 Visual Characteristics:

• Clump-like growing pattern
• Individual stems in bunches
• Grows taller and faster than the rest of lawn
• Large, dark green leaves
• Wide Blades

Large crabgrass is a common invader of manicured turf. Large crabgrass has hairs on all surfaces. It can be identified by its light green appearance and swollen, zig-zag nodes. Crabgrass is a summer annual that re-establishes from seed every spring. Crabgrass can be an indication of elevated soil temperatures and will often establish in last year's grub damaged areas or drought damaged areas.  Elevated mowing heights and judicious fertilization can be extremely effective at reducing competition from crabgrass. Research studies have shown up to 95% reduction in crabgrass when mowing height is increased from to over 3.0 inches. Thin turf in the spring or drought conditions often lead to major infestations of crabgrass especially along concrete surfaces. 

 Visual Characteristics:

• Micro-hairs covering upper & lower leaf surfaces
• Leaves with wavy edges
• Mostly a deep green color 
• Leaves rolled in the bud 
• Blades flat, 1/4 inch wide, sharp pointed

 Smooth crabgrass is the most common summer annual grass problem in managed turf. It is estimated that 90% of the crabgrass in Michigan lawns is smooth crabgrass. Smooth crabgrass lacks the hairs of large crabgrass and can be identified by its light green appearance and swollen, zig-zag nodes. Crabgrass is a summer annual that re-establishes from seed every spring. Crabgrass can be an indication of elevated soil temperatures and will often establish in last year's grub damaged or drought damaged areas.  Elevated mowing heights and judicious fertilization can be extremely effective at reducing competition from crabgrass. Research studies have shown up to 95% reduction in crabgrass when mowing height is increased to over 3.0 inches.  Thin turf in the spring or drought conditions often lead to major infestations of crabgrass especially along concrete surfaces.  

 Visual Characteristics:

• No micro-hairs on the leaf and stems
• Leaves rolled in the bud
• Sheaths compressed, smooth and tinged with purple
• Light green in color

 Dallisgrass is a coarse-textured grass that grows in a clump and slowly increases in diameter as its shallow, underground stems grow outward.   As the clump matures, the center may die and a different grass or weed may be growing in its center. Where large numbers of dallisgrass plants grow together they can form almost a solid planting with uneven texture and poor turfgrass qualities.   Because dallisgrass is a perennial plant, persistence is required to kill it with cultural practices. 

 Visual Characteristics:

• Coarse, grows in bunches
• 1/4"to1/2" blade width
• 2-6 inch stems grow from center point
• Minimal long stems with seed heads
• At the base of the collar is the leaf sheath, which is slightly flattened
• Purplish coloration at the base of the grass stems  

 Quackgrass is a common grassy weed of turfed areas. Quackgrass is a perennial and can often be spotted by its dull blue-green appearance. Because quackgrass spreads by rhizomes (underground stems) it does not always respond well to treatment.  Quackgrass is not easy to manage with cultural practices. Hand digging is not very effective because of the well developed rhizomatous root system. Increased fertilization and mowing frequency can be very effective at masking the presence of quackgrass in a turf. Quackgrass is most obvious during the spring and during drought conditions. and can be easily confused with crabgrass.

 Visual Characteristics:

• Grows quickly in spring and the fall
• Sheaths not compressed
• Lower sheaths have short hairs, upper sheaths are smooth
• Turns brown in summer
• 1/4" wide flat blades

 Yellow nutsedge is a persistent perennial weed of poorly drained soils. Yellow nutsedge is grass-like in its appearance with parallel leaf veination. The stem of nutsedge is triangular with leaves coming off each corner. Nutsedge is very difficult-to-control and can produced hundreds of thousands of seeds per plant per season.   

Nutsedge is most often a problem in heavy soils during years with above average rainfall and the following year.   It will grow faster than the surrounding turf. 

Mature nutlets can remain dormant in the soil for years and are not controlled by herbicide treatment.

 Visual Characteristics:

• Grassy type appearance
• Triangular stem with three leaves
• Glossy Bright Greenish Yellow
• Taller than rest of grass
• Narrow and upright 

Probably the most common weed in maintained turf. Dandelion can tolerate a wide variety of site conditions and soils. A well tap-rooted perennial, dandelion forms a simple rosette of leaves and produces bright yellow flowers on leafless stalks. Dandelion produces a puffball seedhead globe very rapidly after mowing. The seeds are easily dispersed by wind and tracking on equipment. The bright-yellow flowers are easily identifiable in April.  Dandelion is well adapted to many site conditions. It is able to propagate both by seed and vegetatively. Further, the well developed tap root can help regenerate top growth from mowing and herbicide treatment. Raising the mowing height providing adequate fertility will help to favor existing turfgrass and limit or reduce dandelion populations. 

Visual Characteristics:

• Long jagged-tooth leaves
• Flowers are bright yellow
• Flowers transition to fluffy "puffball" seed-heads
• Solitary flowers produced on leafless, hollow stems
• Present from early spring to fall.

Spurge is a late-germinating, low growing, mat-producing summer annual.   Spurge will tolerate some shade but thrives in harsh full-sun baked sites. The reddish somewhat hairy stems of spurge will produce a milky-white latex when broken or injured.  Spurge will survive in harsh conditions where the turfgrass has long-since departed. Spurge must reproduce by seed from year-to-year. Encouraging turfgrass density in the fall and spring should be fairly effective for limiting the presence of spurge in turfed areas. Spurge is most likely to invade when spring conditions have opened the turf from drought or grub damage. Prostrate spurge is a late-germinating summer annual, ideally suited to fill-in voids in the turf during June, July and August. 

 Visual Characteristics:

• Low-growing, spreading clusters
• Reddish-Green stems with hairs
• Broken stems produce milky white substance when damaged
• Flowers form in the axils of the leaves
• Shallow taproot with secondary fibrous roots

 Bull thistle is a clumping biennial that forms a thick taproot in its first growing season. The leaves of bull thistle are covered with 'soft' hairs and needle-like spines on the margin. Leaves of seedlings are not deeply lobed like mature leaves. This is the thistle you stepped on in your bare feet as a kid.   Because bull thistle is a biennial it relies on reproduction by seed. Plants that establish during renovation will persist for up to two seasons. Consistent mowing and good nitrogen fertilization will likely create a turf that resists infestation from a second generation. 

 Visual Characteristics: 

• Bushy, clumped lobed hairy leaves with spiny margins.
• Thick fleshy taproot.
• Often appears as a single specimen. 
• Large purple solitary flower produced on erect stalk during second growing season. 

 White clover is one of the most common weeds of turfgrass. It is frequently included on lists of difficult-to-control weeds. White clover, as with all legumes, has the ability to survive under low soil nitrogen conditions. It can be identified by the three leaflets attached to one petiole. The leaflets are often characterized by a crescent moon-shaped watermark. Clover patches can be very conspicuous under many conditions as it maintains vigorous growth and dark green color. Once established, it may survive under extreme conditions.  White clover is one of several trifoliate weeds of turfgrass. Black medic can be distinguished from white clover by its lack of a crescent-moon shaped watermark and a center leaflet which has a separate petioliole. Yellow woodsorrel is a trifoliate that also lacks the watermark and has deeply indented heart-shaped leaflets. 

 Visual Characteristics:

• Leaves with 3 leaflets, alternate & smooth
• Crescent moon shaped watermark on leaflets
• Little teeth on edge of leaves
• Appears from May to September.
• White flowers formed by an aggregate of 20-40 individual pink to white flower petals that appear in summer

 Common purslane is a mat-forming summer annual that thrives in all soil types. Common purslane has multi-branched red stems with thick fleshy leaves that cluster at the end of the branches. The entire plant is very succulent and resembles a jade plant.  Common purslane prefers high light and warm conditions. This plant reproduces by seeds that are formed in a capsule with a lid that flips open. Solitary yellow flowers will only open with sunny conditions.  Due to its waxy succulent nature, common purslane will tolerate extreme temperatures but not traffic.  Commonly confused with Spurge

 Visual Characteristics:

• Low growing and spreading
• Thick succulent red stems
• Thick leaves, resembling a jade plant
• Flowers yellow buds that only open when sunny
• Thick fleshy taproot with many fibrous roots
• Black seeds

Wild violet is a low-growing clumping (simple) perennial with a dense, fibrous root system and heart-shaped leaves that often cup toward the petiole to form a funnel shape. Wild violet is often considered difficult-to-control due to its aggressive growth, waxy leaves and resistance to most common herbicides. Wild violet is most often found in shaded, fertile sites and prefers moist soils.  Wild violet will colonize shaded, well fertilized, moist areas and can easily out-compete cool-season turf under these conditions. Wild violet often invades lawns from adjacent wooded areas. It is very common to have violet colonize yards in new subdivisions that were recently converted from woods. 

 Visual Characteristics:

• Clumping growth habitat
• Flowers often blue-to-violet, but can be blue, violet, white or off-white
• Heart-shaped waxy leaves that cup toward the petiole
• Dense fibrous root system
• Found in shaded areas, preferring moist soil.
• Flowers appear in mid-may

Perhaps only second to wild violet as the difficult-to-control weed that most often frustrates professional lawncare operators and homeowners. Ground ivy, also known as creeping Charlie, is an aggressive perennial that is ideally suited to many landscape situations. It prefers moist, well-fertilized, shades sites maintained at a low mowing height.

Ground ivy spreads by above-ground runners (stolons) and can quickly overtake large areas.  Ground ivy thrives under conditions that are present in most backyards. It prefers shaded sites but can survive in part- and full-sun conditions as well. Improved drainage, higher mowing height and increased sunlight can be effective as slowing the rate of re-infestation after ground ivy has been removed. 

 Visual Characteristics:

• ​Almost round leaves with scalloped edges. Lobes usually overlap the petiole
• Square stems
• Small purplish-blue funnel shaped flower produced in mid-May
• Strong mint odor when broken

 Black medic is a low-growing creeping weed that is well adapted to many lawn situations. It is most common to find medic in full sun , low maintenance situations. Black medic and white clover grow in similar situation and are often found growing together. Black medic can be mistaken for white clover but is distinguished from white clover by its lack of a crescent-moon shaped watermark and a center leaflet which has a separate petioliole. Yellow woodsorrel is a trifoliate that also lacks the watermark and has deeply indented heart-shaped leaflets.

 Visual Characteristics:

• 3 petal leaflets similar to clover, with slightly toothed margins
• Center leaflets have separate petioliole
• Small bright yellow flowers extending from base of petiole
• Grows low to the ground
• Shallow taproot and secondary roots
• Common from May to September

 Oxalis, or Yellow woodsorrel is a common summer annual in cool-season turf. Yellow woodsorrel is one of the latest germinating summer annual weeds.  Once established, oxalis can be difficult-to-control as summer conditions limit herbicide effectiveness.  Yellow woodsorrel reproduces by seed from year-to-year. Encouraging turfgrass density in the fall and spring should be fairly effective for limiting the presence of woodsorrel in turfed areas. Yellow woodsorrel is most likely to invade when spring conditions have opened the turf from drought or grub damage. Woodsorrel is a late-germinating summer annual, ideally suited to fill-in voids in the turf during June, July and August. 

 Visual Characteristics:

• Bright yellow flowers with 5 petals
• Deeply indented heart shaped leaflets
• Tends to grow upright, but appears to like a creeping vine.
• Shallow taproot with secondary fibrous root

 English Daisy is an escaped ornamental plant that can sometimes be found in lawns and pastures. Prefers heavy, moist, fertile soil and can tolerate mowing heights down to 1 inch. It can be quite showy when flowering in the spring and otherwise undetected in the lawn with its dark green color and low growing habit.  Raising mowing height and increasing sun exposure should improve turfgrass competitiveness. 

 Visual Characteristics:​

• Daisy-like flower heads that are 1/2' to 1" in diameter. Ray flowers can be white to pink with yellow disk flowers.
• Leaves can be both smooth and hairy
• Dark green basal leaves, thinner at base, 1" to 2" long
• Stems can be from 2" to 8" tall
• Grow in dense clusters
• Grow quickly in spring and fall

Broadleaf plantain is probably the second most common broadleaf weed of turf after dandelion. It is extremely well adapted to most sites including dry or wet conditions, heavy soils and very low mowing heights. It is as much of a weed of roadsides and pastures as it is of manicured landscapes.  Plants will remain conspicuously green during drought and throughout the winter.  Broadleaf plantain flowers in the summer on leafless, unbranched stalks that originate from the base of the plant. 

Visual Characteristics:​

• Large oval to elliptical leaves which are a greenish-gray and tend to be red-to-purple at the base.
• Leaves taper to a celery shaped petiole
• Short taproot with a basal rosette