Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant hormones. Herbicides used to clear waste ground, industrial sites, railways and railway embankments are non-selective and kill all plant material with which they come into contact. Smaller quantities are used in forestry, pasture systems, and management of areas set aside as wildlife habitat.

Some plants produce natural herbicides, such as the genus Juglans (walnuts), or the tree of heaven; such action of natural herbicides, and other related chemical interactions, is called allelopathy.

Herbicides are widely used in agriculture and in landscape turf management. In the U.S., they account for about 70% of all agricultural pesticide use.

Prior to the widespread use of chemical herbicides, cultural controls, such as altering soil pH, salinity, or fertility levels, were used to control weeds. Mechanical control (including tillage) was also (and still is) used to control weeds.

Susan Werner is an American singer-songwriter. Much of Werner's work has been in the contemporary folk genre.

Born and raised near Manchester, Iowa, Werner became interested in music at a young age and went on to receive a bachelor's degree in voice at the University of Iowa. In 1987, she moved to Philadelphia, and soon earned a master's degree in voice at Temple University. Werner initially wanted a career in opera, but after seeing a Nanci Griffith performance became inspired and began composing songs of her own on acoustic guitar.

Performing around Philadelphia, [Boston, and New York City, Susan began making a name for herself in the folk scene of the early 1990s. She recorded five albums from 1993 to 2001, and eventually moved to Chicago. Her first five albums were all in the folk genre, but Werner's sixth album, I Can't Be New (2004), was a substantial departure, with original material in the vein of Tin Pan Alley, cabaret, and early jazz torch songs.

Werner's seventh album, The Gospel Truth, was released in March 2007 and addresses themes of religion, faith, social responsibility, as well as religion from an Agnostic's point of view. Her eighth album, Live at Club Passim is collection of original songs (gospel, jazz & folk) recorded with her band: Colleen Sexton, Trina Hamlin & bassist Greg Holt. For her ninth album, Classics, she performs pop music from the sixties and seventies accompanied by chamber instruments.