Texas Invasives

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Federal Noxious Weed

TDA Noxious Weed

TPWD Prohibited Exotic Species

Invasive Plant Atlas of the US

NOTE:

means species is on that list.

Carthamus lanatus

Woolly distaff thistle

Synonym(s): distaff thistle, saffron thistle
Family: Asteraceae (Aster Family)
Duration and Habit: Annual Forb/Herb

Photographer: Ken French
Source: http://www.oregon.gov

Description

Carthamus lanatus can grow up to 3 1/2â€™ tall. The leaves are alternate and have long marginal and terminal spines. Seedlings leaves are less deeply lobed. This plant flower July through August and has yellow flowers that form spiny heads. Woolly distaff thistle is aptly named because it is densely covered in hair.

Native Lookalikes: Currently no information available here yet, or there are no native Texas species that could be confused with Woolly distaff thistle.

Ecological Threat: Carthamus species are believed to be the most serious threat to range and pasture lands. Dense stands can crowd out other vegetation, livestock and recreational access. Â Woolly distaff thistle Â is not grazed as it is not palatable to domestic animals or wildlife. Once established, it is difficult to eliminate because of a persistent seed bank.

Biology & Spread: Dead plants remain standing with thorns, and rigid for at least one year after die back. Woolly distaff thistle has a persistent seed bank, with moderately long lived seeds, and is not eradicated by grazing animals or wildlife because it is unpalatable. Where heavy infestations occur, there is a negative economic impact due to limited forage availability.

History:

U.S. Habitat: Found on seasonally dry hillside range and pasture lands.

Distribution

U.S. Nativity: Introduced to the U.S.

Native Origin: Mediterranean region of Europe and central Europe

U.S. Present: AZ, CA, MA, OK, OR, SC, TX

Distribution in Texas: Reports from Edwards Plateau ecoregion.

Mapping

Invaders of Texas Map: Carthamus lanatus
EDDMapS: Carthamus lanatus
USDA Plants Texas County Map: Carthamus lanatus

Invaders of Texas Observations

List All Observations of Carthamus lanatus reported by Citizen Scientists

OBS# 16133

Native Alternatives

Very similar to smooth distaff thistle, closely related to the safflower.

Management

Manual & Mechanical: Seed spread must be halted, as seeds can be viable up to 10 years in the soil. Plants can be cut just below the soil and removed from the field prior to flowering. Mowing can be effective if done just before flowering. If the soil moisture is high, mowing is not as effective. Dense perennial grasses can outcompete the invasion from C. lanatus.
Biological: Research from France in 1997 presenting strong phenological and practical evidence (field records, plus results of host specificity tests) to support biological control for wooly distaff thistle. Their work documented the fact that three phytophagous species may be considered as specifically attacking C. lanatus, but without damaging field crops of its close relative, C. tinctorius. No biological control for wooly distaff thistle has been pursued in the United States to date (Pers. Comm., Eric Coombs, Jan. 2012).
Chemical: Plants can be killed annually with a selective herbicide. Studies have shown that with the organic herbicide (mixture of capric and caprylic acids) treatments, the most effective options a combination of mowing followed by the organic herbicide. This treatment was slightly less effective compared with aminopyralid but did have better than 95% control of woolly distaff thistle

USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS. MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.

Text References

Oregon Department of Agriculture, Plant Division, Weed Program. 2010. Personal Communication with staff members: Ken French and Eric Coombs, Natural Resource and Biological Control Specialists, respectively.

https://www.cambridge.org/core/journals/invasive-plant-science-and-management/article/abs/conventional-and-organic-options-for-the-control-of-woolly-distaff-thistle-carthamus-lanatus/EFB2FDF01A41BB9DA1FE8E398F16AE09

Online Resources

ODA Risk Assessment. 2010. http://www.oregon.gov/ODA/PLANT/weeds/Pages/profile_woollydistaff.aspx

USDA Plant Database. http://plants.usda.gov/core/profile?symbol=CALA20

https://www.cal-ipc.org/plants/profile/carthamus-lanatus-profile/