Lime sulfur
2293159
224959616
2008-07-11T05:10:54Z
Cole Kitchen
5751
replacing broken link with alternative
In [[horticulture]], '''lime sulfur''' ([[British English|British spelling]] '''lime sulphur''') is a mixture of [[calcium]] [[polysulfide]]s formed by reacting [[calcium hydroxide]] with [[sulfur]]. It can be prepared by boiling calcium hydroxide and sulfur together with a small amount of [[surfactant]]. It is normally used as an aqueous solution, which is reddish-yellow in colour and has a distinctive offensive odour.
== Use ==
Lime sulfur is sold as a spray for [[deciduous]] trees to control [[fungus#Pathogenic species|fungi]], [[bacteria]] and [[insect]]s living or dormant on the surface of the [[bark]]. Lime sulfur burns leaves so it is not as useful for [[evergreen]] plants.
[[Bonsai]] enthusiasts use undiluted lime sulfur to bleach and sterilise portions of trees to give an aged look known as ''Jin''.
Diluted solutions of lime sulfur (between 1:16 and 1:32) are also used as a dip for pets to help control [[ringworm]]. (Note that undiluted lime sulfur is corrosive to the skin and will cause serious injury.)
== Safety ==
Lime sulfur reacts with strong [[acid]]s (including [[Gastric acid|stomach acid]]) to produce highly toxic [[hydrogen sulfide]] (rotten egg gas) and indeed usually has a distinct "rotten egg" odour to it. Lime sulfur is not extremely flammable but combustion produces highly irritating [[sulfur dioxide]] gas.
Safety [[goggles]] and [[glove]]s should be worn while handling lime sulfur. Lime sulfur solutions are strongly [[alkali]]ne (typical commercial concentrates have a [[pH]] over 11.5), and so it is corrosive to living things and can cause [[blindness]] if splashed in the eyes.
== History ==
Lime sulfur is believed to be the earliest synthetic chemical used as a pesticide, being used in the 1840s in [[France]] to control [[grape vine]] [[powdery mildew]] ''Uncinula necator'', which had been introduced from the [[United States of America|USA]] in 1845 and reduced [[wine]] production by 80%. In 1886 it was first used in [[California]] to control [[scale insect|San Jose scale]]. Commencing around 1904, commercial suppliers began to manufacturer lime sulfur; prior to that time, gardeners were expected to manufacture their own. By the 1920s essentially all commercial [[orchard]]s in western countries were protected by regular spraying with lime sulfur. However by the 1940s, lime sulfur began to be replaced by synthetic organic [[fungicide]]s which risked less damage to the crop's foliage.
== References ==
* [http://entweb.clemson.edu/pesticid/history.htm Chronological History of the Development of Insecticides and Control Equipment from 1854 through 1954]
* [http://www.pestmanagement.info/pesticide_history/Two.pdf Background on History of Pesticide Use and Regulation in the United States, Part Two] ([[Portable Document Format|PDF]], 54 kB).
* [http://www.croplifefoundation.org/Documents/Pesticide%20Benefits/Fungicides/Final%20Report/Assembled%20Full%20Report%209-12-05.pdf The Value of Fungicides in U.S. Crop Production], (PDF, 1.1 MB)
[[Category:Calcium compounds]]
[[Category:Sulfur compounds]]
[[Category:Fungicides]]
[[Category:Horticulture]]
[[Category:Gardening]]
[[Category:Alchemical substances]]
[[ja:石灰硫黄合剤]]