{"id":466,"date":"2026-02-11T22:48:42","date_gmt":"2026-02-11T22:48:42","guid":{"rendered":"https:\/\/extension.colostate.edu\/gilpin\/?post_type=resource-cpt&#038;p=466"},"modified":"2026-02-27T23:51:24","modified_gmt":"2026-02-27T23:51:24","slug":"knapweed","status":"publish","type":"resource-cpt","link":"https:\/\/extension.colostate.edu\/gilpin\/resource\/knapweed\/","title":{"rendered":"Knapweed"},"content":{"rendered":"\n<div class=\"wp-block-group wp-block-pattern-longform-content is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<div class=\"wp-block-group wp-block-pattern-quick-facts has-gray-50-background-color has-background is-vertical is-layout-flex wp-container-core-group-is-layout-fe9cc265 wp-block-group-is-layout-flex\">\n<h3 class=\"wp-block-heading\">Noxious Weed Facts<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Knapweeds can cut forage and infestations may reduce grazing capacity 50\u201375%.<\/li>\n\n\n\n<li>They \u201cchemically cheat\u201d by releasing compounds into soil that suppress neighboring plants.<\/li>\n\n\n\n<li>They come back without follow-up: Herbicides can work, but reinvades are common unless you also rebuild competition (like reseeding\/encouraging desirable grasses) and stay consistent.<\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<p>Knapweed can reduce cattle carrying capacity of rangeland or pastures by 50 to 75%. This plant secretes chemical into the soil that kills and prevents other plants from growing.<\/p>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<p><strong>Diffuse knapweed<\/strong> is short-lived perennial, a biennial, or occasionally an annual. Reproduces and spreads from seed. Plant develops single shoot (stem), <strong>1\u20132&#8242; tall or more<\/strong>, usually branched toward top. Flowers usually white but may be purplish.<\/p>\n\n\n\n<p><strong>Spotted knapweed<\/strong> is short-lived, non-creeping perennial that reproduces from seed and forms new shoots each year from a taproot. Produces one or more shoots that are branched and <strong>1\u20133&#8242; tall<\/strong>. Rosette leaves can be <strong>6&#8243; long<\/strong> and deeply lobed. Leaves are similar to diffuse knapweed. Lavender to purple flowers are solitary on shoot tips. Flower heads of spotted knapweed are larger than those of diffuse knapweed.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"338\" height=\"420\" src=\"https:\/\/extension.colostate.edu\/gilpin\/wp-content\/uploads\/sites\/34\/2026\/02\/Knapweed.jpg\" alt=\"Knapweed plant\" class=\"wp-image-564\" srcset=\"https:\/\/extension.colostate.edu\/gilpin\/wp-content\/uploads\/sites\/34\/2026\/02\/Knapweed.jpg 338w, https:\/\/extension.colostate.edu\/gilpin\/wp-content\/uploads\/sites\/34\/2026\/02\/Knapweed.jpg?resize=241,300 241w\" sizes=\"auto, (max-width: 338px) 100vw, 338px\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\" style=\"margin-top:var(--wp--preset--spacing--50);margin-bottom:var(--wp--preset--spacing--50)\">\n<p>Diffuse and spotted knapweed are readily controlled with herbicides. Unless cultural techniques like planting desirable grasses are used, however, weeds will reinvade.<\/p>\n\n\n\n<p><strong><a href=\"https:\/\/extension.colostate.edu\/gilpin\/contact\/\">Contact Gilpin County Extension<\/a><\/strong> for specific herbicide instructions.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Important Notes<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Knapweed spreads rapidly<\/li>\n\n\n\n<li>Knapweed turns into tumbleweeds to disperse seeds<\/li>\n\n\n\n<li>Knapweed will reinvade unless consistently controlled<\/li>\n\n\n\n<li><strong>State law<\/strong>:&nbsp;Diffuse knapweed<strong>&nbsp;<\/strong>must be eradicated or contained in Gilpin County. If you live in a \u201ccontainment\u201d area, it does NOT mean you can let the knapweed grow freely on your property.<\/li>\n<\/ul>\n\n\n\n<p><strong>State law<\/strong>:&nbsp;Diffuse knapweed<strong>&nbsp;<\/strong>must be eradicated or contained in Gilpin County. If you live in a \u201ccontainment\u201d area, it does NOT mean you can let the knapweed grow freely on your property.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<h4 class=\"wp-block-heading\">Additional Information<\/h4>\n\n\n\n<div class=\"wp-block-buttons is-layout-flex wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button is-style-quicklink\"><a tabindex=\"0\" class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/extension.colostate.edu\/resource\/diffuse-and-spotted-knapweed\/\"><strong>Diffuse and Spotted Knapweed | CSU Extension Fact Sheet<\/strong><\/a><\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Noxious Weed Facts Knapweed can reduce cattle carrying capacity of rangeland or pastures by 50 to 75%. This plant secretes chemical into the soil that kills and&#8230;<\/p>\n","protected":false},"author":45,"featured_media":0,"parent":0,"menu_order":0,"template":"","meta":{"_acf_changed":false,"footnotes":""},"area_tax":[],"county_tax":[127],"global-category_tax":[165,179],"global-offering_tax":[],"global-sub-category_tax":[261,287,360],"global-topic_tax":[375],"region_tax":[385],"resource-type_tax":[388],"class_list":["post-466","resource-cpt","type-resource-cpt","status-publish","hentry"],"pp_statuses_selecting_workflow":false,"pp_workflow_action":"current","pp_status_selection":"publish","pp_post_mime_type":"","acf":[],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/resource-cpt\/466","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/resource-cpt"}],"about":[{"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/types\/resource-cpt"}],"author":[{"embeddable":true,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/users\/45"}],"version-history":[{"count":4,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/resource-cpt\/466\/revisions"}],"predecessor-version":[{"id":649,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/resource-cpt\/466\/revisions\/649"}],"wp:attachment":[{"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/media?parent=466"}],"wp:term":[{"taxonomy":"area_tax","embeddable":true,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/area_tax?post=466"},{"taxonomy":"county_tax","embeddable":true,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/county_tax?post=466"},{"taxonomy":"global-category_tax","embeddable":true,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/global-category_tax?post=466"},{"taxonomy":"global-offering_tax","embeddable":true,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/global-offering_tax?post=466"},{"taxonomy":"global-sub-category_tax","embeddable":true,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/global-sub-category_tax?post=466"},{"taxonomy":"global-topic_tax","embeddable":true,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/global-topic_tax?post=466"},{"taxonomy":"region_tax","embeddable":true,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/region_tax?post=466"},{"taxonomy":"resource-type_tax","embeddable":true,"href":"https:\/\/extension.colostate.edu\/gilpin\/wp-json\/wp\/v2\/resource-type_tax?post=466"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}