Weeds - Detailed Information
DETAILED INFORMATION ON SPECIFIC WEEDS
BLACK MEDIC (Medicago lupulina)
Black medic, an annual or sometimes perennial; stems are hairy and branch at the base. Branches are prostrate and spreading. Flowers are small and yellow, in short, globose heads. Controls include soil and turn improvement along with hand removal and/or spot spraying with use of the vinegar or fatty acid products.
BLUEGRASS ANNUAL (Poa annua)
This small cool season grass is a particularly serious weed problem in closely mowed areas. It begins to emerge in late summer and early fall when night temperatures are in the 60’s and moisture is present. Annual bluegrass seeds continue to germinate through the fall, winter and spring – making chemical control more difficult. Favored by moist soil conditions and cool temperatures. It has a strong competitive advantage over warm season grasses from fall through spring. Annual bluegrass is greatly reduced by taller mowing heights and limited use of water. Seed heads in late fall and winter, but seed head development is greatest in the spring and early summer. Controlled with pre and post emergence herbicide like corn gluten meal.
BERMUDAGRASS (Cynodon sactylon) One of the worst weeds of all when you don’t want it. Roundup will kill it but is far more toxic than advertised. Physical removal is best. In beds cover with ½” compost followed by 5 layers of newspaper and shredded mulch. Repeated vinegar sprays will also kill it.
Bindweed Convolvulus arvensis. Introduced from Eurasia. Ranked among the dozen worst perennial weeds in the world. Roots go 6’ deep, can lie in the soil for 30 years and still germinate. Also called wild morning glory. Control by increasing organic matter in the soil.
Brambles Rubus spp. Various berry plants with sharp thorns, spread to form dense masses. Control by pulling up. Spray regrowth with vinegar-based herbicide.
Bull nettle Cnidoscolus texanus. Perennial problem weed in deep, sandy soils with low fertility. Leaves and stems are covered with stinging hairs. Huge underground storage tubers. Control by increasing organic matter in the soil.
Bur clover Medicago hispida. Very low-growing annual cool-weather legume. Small yellow pea like flowers. Seeds contained in a soft-spined bur. Control by increasing soil health.
Canada thistle Circium arvense. Perennial weed, 1 ½-4’ in height. Very difficult to control because of its deep root system. Control by mowing when plant is in full bloom. Root system is exhausted when it is the prettiest.
CHICKWEED (Stellaria media)
Common chickweed is a cool season annual that is a low growing, succulent weed that often spreads out in extensive mats. It may survive summer in moist, shady, cool areas. Seed leaves have prominent midveins and are about four times as long as broad, tapering to a point at the tip. True leaves are broader, opposite, and yellow green. Flowers are small but showy with five deeply cut white petals. Control by mulching beds and improving turf quality.
CLOVER, WHITE Trifolium repens
Perennial. Round flower heads consisting of 20-40 white to pinkish-white florets on long stems. Creeping stems up to 15’ long with dark green three-part leaves. Roots at the joints of the stems. Deeply rooted. Likes cool weather and clay soils. Evergreen when irrigated in the summer. Plant in September or October for best results. Ground cover, cover crop, turf plant. One of the nation’s most important pasture legumes. Great for soil building because of its deep roots and nitrogen fixing ability. Usually considered a weed, but it shouldn’t be. It’s prettier than grass.
Cocklebur Xanthium strumarium. Tall, bushy, annual weed with prickly seeds and sandpaper-like leaves. Grows where excess phosphorous is available.
CRABGRASS (Digitaria sanquinalis) Crabgrass is the major annual weed infesting home lawns. Crabgrass is an annual weed germinating in April, setting seed in August, and dying with the first frost of fall. Crabgrass has tremendous survival reproductive capabilities. A few crabgrass plants in your lawn are acceptable. The most effective way to control crabgrass is to create a dense, healthy turf. Pre-emergence herbicides prevent emergence of crabgrass plants. These products must be applied prior to crabgrass germination which could occur as early as April 1st. Post-emergence herbicides control crabgrass after it has emerged. These products are most effective on small crabgrass. Do not attempt to control crabgrass after about July 15, because crabgrass is too large to control effectively. It is better to simply tolerate the crabgrass until it dies with the first frost. However, it can be killed by spraying the vinegar-based herbicides. The crabgrass control product is also effective.
Warm season perennial is one of the most troublesome weeds in lawns. Begins growth in very early spring and prefers warm, moist areas and high-cut lawns. Tolerate almost any type of soil, reproducing by seeds and rhizomes (underground stems). Has long coarse-textured leaves ½ inch wide and 4-10 inches long. Stems 2-6 inches long radiate from the center of the plant in a star pattern. Seeds are produced on 3-5 finger-like segments that grow from the top of these stems from May to October. Seed stalks grow tall and are unattractive in lawns. Plants form slightly spreading clumps with deep roots. It grows most vigorously in warm summer weather, but can remain green in mild winters. Control with vinegar based herbicides and physical removal followed by an application of compost.
DANDELION (Taraxacum officinale) Perennial. Yellow flowers and powder-puff seed heads. Lettuce like foliage, deep tap root. Flowers are used in cookies and wine, young foliage in salads, the root in tea. The aggressive root system brings minerals from the subsoil up to the surface. Considered a lawn weed. Aeration and proper use of organic fertilizers will greatly reduce the population. Easy to kill if necessary buy spraying with full strength vinegar or removing manually.
DICHONDRA (Dichondra micrantha) I like this plant more than grass in certain situations. Perennial lawn plant or ground cover. Very low growing, spreads by runners. Tiny lily pad looking leaves. Likes partial to heavy shade and moist soil. Excellent between stepping stones. Sometimes used as turf. Many people don’t understand that dichondra is a beautiful ground cover instead of a noxious weed to be sprayed with toxic herbicides. Can be killed with broadleaf herbicides, but why? If you don’t like it, let the soil dry out more between watering. Sometimes sold as Dichondra carolinensis or Dichondra repens.
Dodder Cuscuta spp. Annual weed that reproduces by seed. It starts as an independent plant but establishes a parasitic relationship with the host crop. At this point it has no chlorophyll and looks like yellow string. Control by balancing the minerals in the soil.
FAIRY RING - Toadstool, Mushroom
Fruiting bodies of fungi growing on decaying organic matter. White caps that look like golf balls when young. Expand to 4’-8” in diameter at maturity. Usually appear in lawns in summer after rainy periods. Caps are white at first, then turn gray-green and have distinctive green spores, reddish brown “scales” on the cap, and a ring on the smooth stalk. Fairy rings usually grow in soil where wood is decaying, such as roots or an old stump. Very toxic! Known for their tendency to collect heavy metals from the air and soil.
GOOSEGRASS (Eleusine indica)
Goosegrass, also called wiregrass, is an annual weed that grows as a compressed plant in turf. It appears as a silvery mat forming a pale green clump with a low rosette and flattened stems. Flower stalks are short, stout, and compressed. Seed heads are somewhat similar to those of dallisgrass, but short and stiff. Normally found in compacted areas or areas of heavy wear. Produces seed even under close mowing. Control with healthy soil and spraying vinegar based products.
GRASSBUR (Cenchrus echinatus)
Field sandbur (grassbur) is a summer annual grassy weed adapted to dry, sandy soils but can be found growing in other types of soils as well. Sharp, spiny burs generally start germinating in late spring and will continue to germinate until late summer or early fall months. Will continue to grow until the first hard frost or freeze occurs in the fall. Generally not a problem in well maintained turfgrass areas. Apply compost, corn gluten meal and the entire organic program.
HENBIT (Lamium amplexicaule)
Winter annual. Reproduces by seed and rooting stems. Henbit stems droop and then turn upright to grow to 16 inches tall. They may root where they touch the ground. They are square, green to purplish, and smooth or hairy. The roots are fibrous. ½ to 1 inch long leaves. Henbit flowers are tubular, pink to red to purple. Henbit is often found growing in moist, fertile soils. To control henbit without herbicides, maintain density and health in established turf and avoid thin seedlings in the autumn. Small populations can be hoed or hand pulled or sprayed with vinegar based organic herbicides. Pre-emergence herbicides (corn gluten meal) should be applied in late summer before germination. Mowing usually takes it out because it is taller than the turf.
JOHNSONGRASS (Sorghum halepense)
One of the most troublesome of perennial grasses. It reproduces from underground stems and seeds. Grows in spreading, leafy patches that may be as tall as 6 to 7 feet. Leaves have a prominent whitish midvein, which snap readily when folded over. The flower head is large, open, well branched, and often reddish tinged. Underground stems are thick, fleshy, and segmented. Roots and shoots can rise from each segment. Control by mowing regularly. It can’t stand the pressure.
NUTGRASS (Cyperus esculentus)
Nutsedge, also called purple or yellow nutgrass, is a perennial pest in lawns and gardens. The erect, single, triangular stem has narrow, grass-like, yellow-green leaves. Leaves point outward in 3 directions. Booms in late summer to early fall. Seed heads are yellow-brown. Plant tops die back in the fall, leaving underground tubers to over winter in the soil and repeat the cycle the following year. Nutgrass reproduces by seeds as well as tubers, which are generally the size of popcorn kernels. Weeds sprout in late spring and early summer. A single tuber of yellow nutsedge is capable of producing 146 tubers within 14 weeks following planting and can infest an area 6 ½ feet in diameter. The best control is ¼ - ½ cup of liquid molassess per gallon of water. Drench 9 – 10 sq. ft. with 1 gallon of mix.
PURSLANE (Portulaca oleracea)
Common purslane is an annual that grows rapidly in spring and summer. It thrives under dry conditions but also competes well in irrigated situations. Low growing. Leaves are very succulent and often tinged red. Small yellow flowers are born singly or in clusters of two or three. Flowers usually open only on sunny mornings. Purslane seeds are very tiny and produced in abundance. Entire plant is edible and nutritious.
This an Aster has a small white flower in late spring. Usually is found growing in fairly poor soils. It will not compete with turfgrasses if the lawn is healthy. Easy to control by increasing the vigor of the lawn. Use the organic program, topdress problem with compost and water consistently. Dry molassess at 10 – 20 lbs per 1000 sq.ft. will also help.