Insects like the Western corn rootworm and plants like the horseweed and pigweed that disrupt farming could be rendered nonresistant to pesticides and herbicides, or changed so they no longer like the taste of the crops they prey on.
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Farmers are advised to include 2,4-D or dicamba in a burndown application prior to planting to control horseweed.
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Horseweed is commonly considered a weed, and in Ohio, it has been declared a noxious weed. It can be found in fields, meadows, and gardens throughout its native range. Horseweed infestations have reduced soybean yields by as much as 83%. It is an especially problematic weed in no- till agriculture, as it is often resistant to glyphosate and other herbicides.
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Its flower heads have white ray florets. Common names include flax- leaf fleabane, wavy-leaf fleabane, Argentine fleabane, hairy horseweed, asthma weed and hairy fleabane.
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Canadian fleabane (Erigeron canadensis) essential oil in a clear glass vial Erigeron canadensis (synonym Conyza canadensis) is an annual plant native throughout most of North America and Central America. It is also widely naturalized in Eurasia and Australia. Common names include horseweed, Canadian horseweed, Canadian fleabane, coltstail, marestail, and butterweed. It was the first weed to have developed glyphosate resistance, reported in 2001 from Delaware.
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Conyza (horseweed, butterweed or fleabane) is a genus of flowering plants in the sunflower family.Lessing, Christian Friedrich. 1832. Synopsis Generum Compositarum 203–204 in LatinTropicos, Conyza Less.Cronquist, A. 1943.
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Recently, rapid emergence of weeds thought to be resistant to Roundup have been observed. Horseweed, giant ragweed and pigweed, among others have been found growing with crops across the United States. Insects including corn rootworm and bollworm have also begun showing signs of resistance. In response, Monsanto has continued to develop new products.
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Common chicory is also known as blue daisy, blue dandelion, blue sailors, blue weed, bunk, coffeeweed, cornflower, hendibeh, horseweed, ragged sailors, succory, wild bachelor's buttons, and wild endive (note: "cornflower" is commonly applied to Centaurea cyanus). Common names for varieties of var. foliosum include endive, radicchio, radichetta, Belgian endive, French endive, red endive, sugarloaf, and witloof (or witlof).
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Later instars can live freely in a web on the leaf. Larval foodplants recorded include, on common fleabane (Pulicaria dysenterica) in the United Kingdom. In Australia on capeweed (Arctotheca calendula), spear thistle (Cirsium vulgare), horseweed (Erigeron canadensis), cotton thistle (Onopordum acanthium) and golden everlasting (Xerochrysum bracteatum); and in Réunion on globe artichoke (Cynara scolymus). De Prins, J. & De Prins, W. 2014.
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Flora of North America, Horseweed, Conyza Lessing The species are annual or perennial herbaceous plants, rarely shrubs, growing to 1–2 m tall. The stems are erect, branched, with alternate leaves. The flowers are produced in inflorescences, with several inflorescences loosely clustered on each stem. Many species of the genus Conyza are ruderal species and some have been found to be resistant to the herbicide glyphosate.
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Ambrosia trifida, the giant ragweed, is a species of flowering plant in the sunflower family. It is native to North America, where it is widespread in Canada, the United States, and northern Mexico. It is present in Europe and Asia as an introduced species, and it is known as a common weed in many regions. Its common names include great ragweed, Texan great ragweed, giant ragweed, tall ragweed, blood ragweed, perennial ragweed, horseweed,Ambrosia trifida.
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Nectar availability is likely to influence Karner blue butterfly abundance. In a right-of-way in west-central Wisconsin, the frequency that Karner blue butterflies stayed in an area between recaptures was significantly (p<0.05) positively related to percent cover of nectar flowers such as Canadian horseweed (Conyza canadensis var. canadensis) and spotted beebalm (Monarda punctata). Preliminary results from a study in southeastern Minnesota suggest that openings where Karner blue butterflies were detected tended to have more flowering nectar species.
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Conyza ramosissima (dwarf horseweed) is a species of North American plants in the daisy family. It is widespread and common across the central part of the United States, its range extending from New Mexico east to Alabama and north as far as Pennsylvania, Ontario, and North Dakota.Biota of North America Program 2014 county distribution map, Erigeron divaricatus The oldest name for the species is Erigeron divaricatus, coined in 1803Michaux, André 1803. Flora Boreali-Americana 2: 123 in Latin and still used by some sources.
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Horseweed originated in North America and is very widespread there,Biota of North America Program, 2014 county distribution map, Erigeron canadensis but has spread to inhabited areas of most of the temperate zone of Asia,Flora of China, Erigeron canadensis Linnaeus, Sp. Pl. 2: 863. 1753. 小蓬草 xiao peng cao Europe,Altervista Flora Italiana, Cespica canadese, avoadinha, Berufkraut, Erigeron canadensis L. includes photos and European distribution map and Australia.Atlas of Living Australia, Conyza canadensis (L.) Cronquist Canadian Fleabane It is found in Britain from northern Scotland to Cornwall, growing as a weed of arable land and man-made environments. It considered invasive in China.
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While any plant can be a weed, approximately 250 plant species are sufficiently troublesome, cosmopolitan and economically injurious to warrant targeted research into their biology to assist in their management and control. Examples of some of these troublesome weed species in North America are Palmer amaranth (Amaranthus palmeri S. Watson), common lambsquarter (Chenopodium album L.), horseweed (Erigeron canadensis L.), morningglory (Ipomoea spp.), waterhemp (Amaranthus tuberculatus (Moq.) J. D. Sauer) and common ragweed (Ambrosia artemisiifolia L.). Some weed science researchers provide extension resources for farmers and land managers by trialing a variety of weed control tools and tactics on a specific weed, publishing the results and providing recommendations for their future management. Other researchers may study the biology of weed seeds in order to determine how long weed seeds can remain viable in a soil.
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