Weed Identification in Pastures, Hayfields, and Sprayfields This publication is designed to help you identify common weeds found in southeastern North Carolina pastures, hayfields, and sprayfields. It presents descriptions and pictures of some of the most common weeds, and it provides references for other weeds that are not in this publication. Weeds are categorized here as broadleaf, grass, or other, and as warm season or cool season. This publication does not recommend specific chemical control methods because differences in situa- tions, rapidly changing labels, and new products make generalized recommendations impracti- cal. Call your local Extension agent to discuss the best control methods for your farm. Why Identify Weeds? Cultural control increases the competitive- weed is a plant growing in a place where ness of forage. Fertilizing to improve soil pH and Ayou do not want it to grow. In pastures and fertility maintains grass stands and decreases hayfields, it is impossible to have a “pure” stand weed competition. Once you are sure soil fertility of grass; there will always be plants that volunteer and pH are correct, use the four control methods from the seedbank or from neighboring fields. below in combination to fight weeds. The effec- New volunteer species can mean more and better tiveness of control methods depends on timing. pasture forage, or it can mean losses of forage • Grazing management is one way to control quality and yield. Weeds also have the potential weeds in a pasture situation. This control allows to cause injury or death to livestock if the weed desired plants to become strong and outcompete plants are toxic. Weeds can reduce hay yield and the weeds. Rotational grazing helps to control quality, and they can interfere with hay drying. weeds by giving desired plants the opportunity For these reasons, weed control is very important. to rest and grow undisturbed before being grazed The first step in weed control is identifying again. In rotational grazing systems, animals the weed or weeds you have, which will allow you will often consume weeds they would avoid in to determine whether they need to be controlled. continuous grazing systems. Graze or mow at the Take time to walk through your fields and scout proper height, and do not cut or mow too short. at least 10 to 15 sites in a field. Identify all the • Mechanical control usually involves mow- plants and seedlings at each site. A good time to ing to control weeds. Mowing is usually more assess your fields is between seasons and about effective on broadleaf weeds than grass weeds. 1 week after cutting or grazing. Keep a record of Mowing does have negatives: it increases fuel the weeds you have in each field and when you costs, it may not help with large weeds, and it can start seeing them. This will help you determine spread seeds around, encouraging more weed whether your control program is working. Some growth. If there is no chemical control labeled weeds may take a few years to get under control. for a particular weed or if weeds are too mature, Prevention is any activity that keeps weeds mowing may be your only choice for decreasing from getting into your pasture. Many weeds are competitiveness. Burning, when safe and permit- spread by seeds that are dispersed by hay bales, ted, is another option for control of some weeds plants that reach maturity, livestock movements, in some forages. mowing equipment, wind, water, and wildlife. • Biological control involves the use of natu- Weeds can also be introduced when you plant ral agents such as plants, herbivores, insects, grass seeds that are contaminated with weed and nematodes to suppress weeds. Biological seeds. When you buy seed, make sure you are control is a relatively new area, but progress is getting the best seed for your money. This is why being made in developing and refining biological certified seeds are recommended. control methods. Biological control is usually not Weed Identification in Pastures, Hayfields, and Sprayfields complete and may take several years to become sufficiently effective. • Chemical control is the use of herbicides that kill weeds by inhibit- ing the plant growth process. Select an herbicide based on desired forage species, weed species present, cost, and ease of application. It is very important to apply herbicides at the correct time and rate. Consider spot- spraying weeds. The best time to control weeds postemergence with herbicides is when the weeds have germinated, are young, and are actively growing. This time varies according to whether the weeds in question are cool-season weeds or warm-season weeds. Cool-season weeds: The best time Source: Turfgrass Program, University of Georgia to control with herbicides is from October through December. It is also possible to control cool-season weeds and the reproductive structures (fruits, Cotyledon—A leaf of the embryo from February through April. seeds, flowers) in the second year. of a seed plant that, upon germina- Warm-season weeds: The best Blade—The flat portion of the tion, either remains in the seed or time to control with herbicides is from grass leaf above the sheath. emerges, enlarges, and becomes green. April to mid-July for most species. Bract—A modified or specialized Crown—A region of compressed Always read and follow herbicide leaf. stem tissue from which new shoots label directions, and pay attention to Broadleaf—Plants with flattened are produced, generally found near any grazing and haying restrictions. leaves; dicots, i.e., plants that possess the surface of the soil. The label is the law! two seedling leaves. Leaves are gener- Cultivar—A word derived from ally wider than they are long and have two words, «cultivated variety,» refer- Plant Glossary netlike veins. They can have either ring to any cultivated variety of a ALS-inhibiting herbicides—A round or square stems, and growth particular plant species. class of herbicides that inhibit synthesis can be upright, prostrate, or vining. Dormancy—A period when of branched amino acids in plants by Broadleaf plants can have a taproot, growth and development is temporar- inhibiting acetolactate synthase (ALS). a bulbous root, or fibrous roots. They ily suspended. Alternate—A type of leaf often have showy flowers. Three key Fibrous roots—A root system arrangement characterized by a single indicators help categorize a plant made up of many threadlike members leaf at each node. almost definitively as a broadleaf, of more or less equal length, as in Annual—A plant that germinates, rather than a grass, rush, or sedge: a most grasses. A fibrous root system flowers, and produces seed in one year. square stem, a nonlinear leaf shape, or serves to anchor the plant. Apex—The tip of a leaf or other a nonfibrous root system. Flower—Reproductive structure of plant part. Bunchgrass—A nonspreading some seed-bearing plants, characteris- Auricle—A clawlike appendage grass that lacks rhizomes and stolons. tically having either specialized male projecting from the collar of the leaf Cladodes—Swollen, water-storing or female organs or both male and in a grass plant. stem segments that are not leaves. female organs, such as stamens and a Awn—A fibrous bristle or beard Collar—A narrow band marking pistil, enclosed in an outer envelope of that is an extension of the midrib of the place where the blade and sheath petals and sepals. This structure usu- the large outer bract. of a grass leaf join. A divided collar is ally has showy or colorful parts. Basal—A new plant arising from divided by the midrib, and a continu- Inflorescence—The flowering the base of the stem. ous collar is not divided by the midrib. part of a grass or broadleaf. Biennial—A plant that generally Cool-season plant—A plant that Keeled—A descriptor for a longi- lives two years, forming the vegetative exhibits optimum growth during tudinal prominence on the back of a structures (roots, leaves) in the first year spring and fall months. structure. 2 Weed Identification in Pastures, Hayfields, and Sprayfields Lateral—On the side. and act as a protective covering of the Leaf—An extension of a plant’s Broadleaf Plant Structure inner parts in the bud. stem that is primarily the plant’s food- Sheath—The portion of a leaf base making organ in photosynthesis. surrounding the stem of a grass. Can Leaf axil—The location where the be open, closed, or split with overlap- petiole attaches to the stem. ping margins, depending on the spe- Leaflet—One of the segments of cies of grass. a compound leaf. Spike—One type of seedhead Legume—A plant that belongs of grass, at the end of the stem, not to the family Leguminosae (or branched. Fabaceae). Legumes live in a symbi- Sprig—A rhizome or stolon of a otic relationship with bacteria that grass, harvested and transplanted to reside in structures on their roots establish a pasture or hayfield. called nodules. These bacteria are able Stem—The stalk of a plant that to take nitrogen from the air, which Source: Center for Turfgrass Envi- supports a leaf, flower, or fruit. exists in a form that plants cannot ronmental Research and Education, Stolon—An aboveground creep- use, and convert it into compounds NC State University ing stem capable of producing roots that plants can use. and tillers at the nodes. Ligule—A membranelike tis- normally being the first organ to grow. Summer annual—A plant that sue or row of delicate hairs typically It grows downward into the soil and germinates, flowers, and produces seed found in grasses at the junction of the produces lateral secondary roots that in one year and that exhibits optimum leaf sheath and blade.