Editing Horseradish (section)

==Cultivation==
{{more citations needed|section|date=November 2019}}
[[File:Horse-radish plate no 6 bv73c1191 bk128b698 crop.jpg|thumb|right|Horseradish, from ''The Book of Health'', 1898, by Henry Munson Lyman]]
Horseradish is [[perennial plant|perennial]] in [[hardiness zones]] 2–9 and can be grown as an [[annual plant|annual]] in other zones, although not as successfully as in zones with both a long growing season and winter temperatures cold enough to ensure plant dormancy. After the first frost in autumn kills the leaves, the root is dug and divided. The main root is harvested and one or more large offshoots of the main root are replanted to produce next year's crop. Horseradish left undisturbed in the garden spreads via underground shoots and can become [[invasive species|invasive]]. Older roots left in the ground become woody, after which they are no longer culinarily useful, although older plants can be dug and re-divided to start new plants. The early season leaves can be distinctively different, asymmetric spiky before the mature typical flat broad leaves start to be developed.

===Pests and diseases===
Introduced by accident, "cabbageworms", the larvae of ''[[Pieris rapae]]'', are a common caterpillar pest in horseradish. Mature caterpillars chew large, ragged holes in the leaves leaving the large veins intact. Handpicking is an effective control strategy in home gardens.<ref>{{cite web |url=http://www.extension.umn.edu/yardandgarden/ygbriefs/e253caterpillarpests-cole.html |title=Caterpillar Pests of Cole Crops in Home Gardens |access-date=2007-09-30 |author=Suzanne Wold-Burkness and Jeff Hahn |publisher=University of Minnesota |url-status=dead |archive-url=https://web.archive.org/web/20071002043657/http://www.extension.umn.edu/yardandgarden/ygbriefs/e253caterpillarpests-cole.html |archive-date=2007-10-02 }}</ref> Another common pest of horseradish is the mustard leaf beetle (''[[Phaedon cochleariae]]'').<ref>{{Cite journal |last1=Gross |first1=Jürgen |last2=Müller |first2=Caroline |last3=Vilcinskas |first3=Andreas |last4=Hilker |first4=Monika |date=November 1998 |title=Antimicrobial Activity of Exocrine Glandular Secretions, Hemolymph, and Larval Regurgitate of the Mustard Leaf BeetlePhaedon cochleariae |url=https://linkinghub.elsevier.com/retrieve/pii/S0022201198947814 |journal=Journal of Invertebrate Pathology |language=en |volume=72 |issue=3 |pages=296–303 |doi=10.1006/jipa.1998.4781 |pmid=9784354}}</ref> These beetles are undeterred by the defense mechanisms produced by Brassicaceae plants like horseradish.<ref name=":new2">{{cite journal |last1=Friedrichs |first1=Jeanne |last2=Schweiger |first2=Rabea |last3=Geisler |first3=Svenja |last4=Mix |first4=Andreas |last5=Wittstock |first5=Ute |last6=Müller |first6=Caroline |date=September 2020 |title=Novel glucosinolate metabolism in larvae of the leaf beetle Phaedon cochleariae |journal=Insect Biochemistry and Molecular Biology |volume=124 |pages=103431 |doi=10.1016/j.ibmb.2020.103431 |pmid=32653632}}</ref>