Bull Thistle: Spot It & Stop It

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Top view of bull thistle

Bull thistles are invasive and wreak havoc on a variety of landscapes. This menace thrives in direct sunlight and dry soils that lack nutrients, often producing hundreds of thousands of seeds per plant. Proper identification and understanding of this sharp, prickly weed is key to controlling it.

How to spot thistles

  • Bull thistle has prickly leaves, and the stem has spines or prickles.
  • Arranged alternately on the flowering stem, leaves are lanceolate with deeply cut margins. Bull thistle leaves also have coarse hair on the top and softer whitish hairs on the underside.
  • Bull thistle commonly invades the least tended to parts of landscapes, especially in fields and prairies.
  • Flowers are rose to reddish-purple in color.

How to control thistles

Once thistles are correctly identified, effective control can be achieved.

  • Early identification
    Accurate identification of thistles is crucial for achieving effective control. Given their invasive nature, early detection and prompt action are imperative. Bull thistles propagate solely through seeds, making application prior to seed set the most effective.
  • Soil control
    Bull thistles boast an extensive root system, thriving in dry soil with limited nutrients and full sun, making their elimination challenging. To prevent a thistle invasion, ensure proper soil hydration.
  • Preemergence herbicides
    Optimum postemergence control around labeled ornamentals and golf course fairways and roughs, with utmost care for even the most sensitive turfgrasses, can be achieved by applying Lontrel® specialty herbicide to small, actively growing bull thistles. This fast-acting herbicide becomes rainfast within two hours, ensuring effective results.
  • Follow the label
    Consult the product label for recommended application rates for your area as well as seeding and reseeding rates.

Spotting problem weeds and properly identifying them is the first step to healthy turf. For more information and treatment options, check out these online resources.


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