Jump to content

Pyrethrum

From Wikipedia, the free encyclopedia
This is an old revision of this page, as edited by 72.141.100.118 (talk) at 16:02, 6 May 2018 (→Description). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Pyrethrum was a genus of several Old World plants now classified as Chrysanthemum or Tanacetum (e.g., C. coccineum) which are cultivated as ornamentals for their showy flower heads. Pyrethrum continues to be used as a common name for plants formerly included in the genus Pyrethrum. Pyrethrum is also the name of a natural insecticide made from the dried flower heads of Chrysanthemum cinerariifolium and Chrysanthemum coccineum.

Description

Some members C. coccineum also contains insecticidal pyrethrum substances, but it is a poor source compared to C. cinerariifolium.

  • Other species, such as C. balsamita and C. marshalli, also contain insecticidal substances, but are less effective than the two species mentioned above.
Tanacetum cinerariifolium

Insecticides

Sprays

Pyrethrum has been used for centuries as an insecticide,[1] and as a lice remedy in the Middle East (Persian powder, also known as "Persian pellitory"). It was sold worldwide under the brand Zacherlin by Austrian industrialist J. Zacherl.[2] It is one of the most commonly used non-synthetic insecticides allowed in certified organic agriculture.[3]

The flowers should be dried and then crushed and mixed with water.

  • Pyrethroids are synthetic insecticides based on natural pyrethrum (pyrethrins); one common example is permethrin. A common formulation of pyrethrin is in preparations containing the synthetic chemical piperonyl butoxide: this has the effect of enhancing the toxicity to insects and speeding the effects when compared with pyrethrins used alone. These formulations are known as synergized pyrethrins.

Toxicity

Rat and rabbit LD50 levels for pyrethrum are high (safe), with doses in some cases of about 1% of the animal's body weight required to cause significant mortality similar to levels in synthetic pyrethroids.[4] Nevertheless, pyrethrum should be handled with the same caution as synthetic insecticides.[5]

People can be exposed to pyrethrum as a mixture of cinerin, jasmolin, and pyrethrin in the workplace by breathing it in, getting it in the eyes or on the skin, or swallowing it. The Occupational Safety and Health Administration (OSHA) has set the legal limit (Permissible exposure limit) for pyrethrum exposure in the workplace as 5 mg/m3 over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a Recommended exposure limit (REL) of 5 mg/m3 over an 8-hour workday. At levels of 5000 mg/m3, pyrethrum is immediately dangerous to life and health. People exposed to pyrethrum may experience symptoms including pruritus (itching), dermatitis, papules, erythema (red skin), rhinorrhea (runny nose), sneezing, and asthma.[6]

Companion planting

Because chrysanthemums contain pyrethrums, they are used as companion plants to repel pest insects from nearby crops and ornamental plants.[7] They are thought to repel aphids, bed bugs (Cimex lectularius), leafhoppers, spider mites, harlequin bugs, ticks, pickleworms, and imported cabbage worms, among others, in gardens and farms. For example, they are planted among broccoli plants for protection from several common insect pests.

Common names

Common names for Chrysanthemum cinerariifolium include:

  • Pyrethrum
  • Pyrethrum daisy
  • Dalmatian pyrethrum
  • Dalmatian chrysanthemum
  • Dalmatian insect flower
  • Dalmatian pellitory
  • Big daisy

Common names for Chrysanthemum coccineum include:

  • Pyrethrum
  • Pyrethrum daisy
  • Painted daisy
  • Persian chrysanthemum
  • Persian insect flower
  • Persian pellitory
  • Caucasian insect powder plant

See also

References

  1. ^ Bioaromatica The history of pyrethrum
  2. ^ US patent 308172, Johann Zacherl, "Pyrethrum Soap", issued November 18, 1884 
  3. ^ Some Pesticides Permitted in Organic Gardening, by Laura Pickett Pottorff, Colorado State University Cooperative Extension, January 5, 2010.
  4. ^ Pesticide Toxicity Profile: Synthetic Pyrethroid Pesticides, by Frederick M. Fisher, University of Florida IFAS Extension Service, 2013
  5. ^ insecticide (botanical, mineral, synthetic) toxicity to mammals Electronic Data Information Source of University of Florida
  6. ^ "CDC - NIOSH Pocket Guide to Chemical Hazards - Pyrethrum". www.cdc.gov. Retrieved October 23, 2015.
  7. ^ Riotte, Louise (1998). Carrots Love Tomatoes. North Adams, MA: Storey Publishing, LLC. p. 72. ISBN 978-1-58017-027-7.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Pyrethrum&oldid=839921771"