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Orange hawkweed

Orange hawkweed

Orange hawkweed

(Hieracium aurantiacum)

Priority: -  Control

Tags: Agricultural | Terrestrial | Biocontrol

Identification and Reproduction

Identification: 

  • Orange hawkweed is an invasive flowering perennial in the Asteraceae (daisy) family.
  • Single erect stem can grow upto one metre tall and is covered in hairs but leafless. 

   

  • It has very hairy leaves that form in a central basal rosette. 
  • Flowers are orange and dandelion-like. 

Reproduction: 

  • Spreads by seeds that are easily dispersed by wind
  • Vegetatively grow through stolons (above ground) and rhizomes (below ground). 

Habitat & Ecology

  • Orange hawkweed prefers well-drained, coarse-textured soils.
  • It will invade open and disturbed areas like pastures and roadsides as well as wetlands.
  • Similar to yellow hawkweed, it is knwon to hybridize with native species. 

Impacts

Social: 

  • Displaces crop yields in agriculture. 
  • Reduces forage availablilty for livestock 
  • Since orange hawkweed can establish quickly on deforested sites it can impact reforestation measures. 

Ecological: 

  • It outcompetes other native plants, reducing forage and biodiversity. 
  • Forms monocultures. 
  • Has allelopathic properties that prevents growth of other plants.

Management

Mechanical/Manual Control: 

  • Prior to flowering digging may be effective. Ensure that entire roots are removed. 
  • Small infestations can be hand pulled. Be sure to collect all stolon and root fragments to prevent regrowth. 

Biological Control: 

Currently a stolon-feeding wasp and a root-feeding hover fly are being researced in BC. 

Chemical Control: 

  • Picloram, aminopyralid, 2,4-D are effective on orange hawkweed. 
  • Another consideration is to fertilize surrounding native vegetation in the spring. This will help facilitate growth to help outcompete with the invader. 
  • Please carefully read and follow herbicide labels prior to application. 

For alternative planting options to yellow flag iris download the ISCBC's Grow Me Instead brochure (pg. 39 and 40).

Resources

Download the Invasive Species Council of BC's Factsheet on Orange Hawkweed here

Header photo (Sapin88).