Both giant foxtail and yellow foxtail are summer annuals that emerge from early May through June. While both produce thousands of seeds and a hair-like ligule, giant foxtail has and short hairs on its blade?EUR??,,????'???s upper surface. Yellow foxtail has long hairs on its blade near the collar, a flat stem, and a purplish-red color near its base. www.fauxflowers.net

It is estimated that herbicides comprise more than 76% of the total pesticide sales in the United States. Undoubtedly, they account for a major part of your landscaping budget as well. With this magnitude of herbicide usage, weed control needs to be efficient and cost effective. Additionally, since preventing weeds consists of more than just using herbicides, other methods of organic control should also supplement chemicals in order to nip weeds in the bud.

A weed is defined as any plant that is a hazard, nuisance, or causes damage to turf. The bane of all turfgrass managers, weeds can ruin the look and feel of your landscape. Always a constant battle, the prevention of weeds takes careful planning and timing as well as the proper execution. Therefore, the first step of weed management is proper identification.

Common lambsquarters, a summer annual, features lanceolate shaped cotyledons and true leaves with a white mealy substance on them. A prolific seed producer that can remain viable in the soil for many years, it has an opposite then alternate leaf arrangement and emerges from mid-April to mid-June. peanut.tamu.edu

Crabgrass is a summer annual that germinates from mid spring to mid summer. Featuring a membranous ligule, it has a hairy blade and sheath as well as a finger-like seed head. Able to tolerate hot, dry conditions and produce a large amount of seeds, this opportunistic weed does not do well when shaded. www.johnsonsflowers.com

Classification of Weeds

Weeds are classified as grasses, broadleafs, and sedges. They can further be classified by the length of their life cycle (annual, biennial, and perennial). The classification of weeds based on the length of their life cycle may not be obvious on visual inspection but will have a great impact on the selection and/or success of control procedures. The life cycle characteristic will become an automatic association as specific weeds and weed types are learned.

Grass Weeds

True grass weeds have hollow, rounded stems and nodes (joints) that are closed and hard. The leaf blades have parallel veins, are much longer than they are wide, and alternate on each side of the stem. Some examples are crabgrass, goosegrass, crowfootgrass, sandbur, annual bluegrass, torpedograss, and vaseygrass.

Broadleaf Weeds

Broadleaf weeds are a highly variable group of plants but most have showy flowers and net-like veins in their leaves. They are easy to separate from grasses due to their generally different leaf structure and habits of growth. Some examples of broadleaf weeds are cudweed, creeping charlie, henbit spurges, burning nettle, pennywort, creeping beggarweed, cocklebur, sicklepod, and Florida beggarweed.

Common Ragweed, a summer annual, features an opposite leaf arrangement, which are ?EUR??,,????'??lacy?EUR??,,????'?? and hairy and spoon shaped cotyledons. Each plant produces about 3000 seeds, which can remain viable for up to 40 years. www.easttennesseewildflowers.com

A summer annual, velvetleaf features heart-shaped leaves and cotyledons, toothed leaf margins, as well as stems and leaves that have densely hairy, velvety feel. Emerging from mid May through June, it?EUR??,,????'???s flowers are circular cup-shaped disks that contain multiple seeds, which can remain viable for up to 50 years. twig.tamu.edu

Sedges

Sedges are an important group of “grass-like” weeds, but they are not true grasses. They are characterized by a solid, triangular-shaped stem with leaves extending in three directions and are usually referred to as nutgrass.

There are two major perennial sedges. Yellow nutsedge is yellowish green in color and reproduces by seed, rhizomes, and tubers. The rhizomes radiate from the plant with a single bulb or tuber at the end which may produce new plants. Purple nutsedge is usually smaller in size than yellow nutsedge, has reddish purple seed heads, and produces a series of bulbs on radiating rhizomes called “tuber chains.”

Annual Weeds

Annual weeds, as the name implies, complete their life cycle within one year. They germinate from seed, produce seed, and die in 12 months or less. They may be annual grasses, sedges, or broadleaved weeds. In addition, their life cycle may begin at different seasons of the year.

Summer annuals emerge in the spring and mature before winter. Weeds such as crabgrass and cocklebur are typical summer annuals. Similarly, winter annual weeds sprout from seed in the fall, and complete their life cycle before summer of the next calendar year. Wild radish, henbit, annual bluegrass, and chickweed are examples of winter annual weeds.

Common Chickweed, a winter annual, emerges from late August to spring. It has opposite, broadly ovate/egg-shaped leaves, is light green in color, and has a row of hairs on the stem. webshots.com/earthmagicherbs

Yellow nutsedge is a perennial weed with a triangular stem and shiny yellowish-green, grass-like blades. Thriving in a number of turfgrasses, from well-drained, sandy to wet soils, infestations often start in wet areas. twig.tamu.edu

Biennial Weeds

Compared to annual weeds, biennial weeds are few in number. These weeds have a 2-year life cycle. They germinate from seed in the fall, develop large root systems and a compact cluster of leaves during the first year.

The second year they mature, produce seed, and die. Examples of biennial weeds are cudweed, Carolina false dandelion, wild carrot, and bull thistle.

Perennial Weeds

Weeds that live more than two years are perennials. They reproduce by vegetative parts such as tubers, bulbs, rhizomes (underground stems) or stolons (above-ground stems). Some also produce seed in addition to vegetative reproduction.

Eastern black nightshade is a summer annual that features ovate leaves with some hair and pointed tips. Emerging in mid-May to late June, all plant parts are considered poisonous. Its leaves have toothed edges, have a purple color under-leaf and produce black/purple berries when mature. Its seeds can remain viable for several years in the soil. www.bio.brandeis.edu

Preventive measures

Pre-emergent herbicides should used to prevent germination of annual weeds as their seeds try to sprout. They must be applied a few weeks prior to the prime germination. For cool-season weeds, herbicides must be applied in early September. To prevent summer weeds, apply pre-emergent granules in early March.

Two other categories of herbicides deserve special mention. Apply Image or Manage to control nutsedge in turf and certain landscaped areas. And, to eliminate existing grass without leaving a harmful residue in the soil, apply a glyphosate such as Roundup.