Citrumelo

{{short description|Taxon}}

{{Refimprove|date=January 2017}}

{{Infobox cultivar

| name = Citrumelo

| image =

| image_caption =

| hybrid = Poncirus trifoliata (Japanese bitter orange) x Citrus × paradisi (grapefruit)

| origin =

}}

Citrumelo (× Citroncirus spp.) is also called Swingle citrumelo trifoliate hybrid, because it is cold hardy and is a hybrid between a 'Duncan' grapefruit and a trifoliate orange (Poncirus trifoliata (L.) Raf.), developed by Walter Tennyson Swingle.

Citrumelo is widely employed as a citrus rootstock,{{cite journal |author1=Francisco de Assis Alves Mourão Filho |author2=Eduardo Augusto Girardi |author3=Hilton Thadeu Zarate do Couto |title='Swingle' citrumelo propagation by cuttings for citrus nursery tree production or inarching |journal=Scientia Horticulturae |volume=120 |issue=2 |pages=207–212 |date=April 2009 |doi=10.1016/j.scienta.2008.11.001|bibcode=2009ScHor.120..207M }} being resistant to the severe citrus tristeza virus and to phytophthora root rot as well as to blight, cold, and citrus nematode.[https://citrusvariety.ucr.edu/crc3771 Swingle citrumelo trifoliate hybrid (CRC 3771)] at Citrus Variety Collection The trees can survive temperatures into the teens (Fahrenheit);{{Cite web |title=Citrumelo Hardy Grapefruit |url=https://onegreenworld.com/product/citrumelo/ |publisher=onegreenworld.com |access-date=17 January 2017}} one specimen in North Carolina reportedly survived temperatures below zero Fahrenheit.{{Cite web |title=Citrumelo of Nottingham |url=http://www.homecitrusgrowers.co.uk/citrumelos/citrumelonottingham.html |publisher=homecitrusgrowers.co.uk |access-date=17 January 2017}}

The fruit are yellow, and up to 4 inches across in size. Their taste is described as "like a cross between a lemon and a grapefruit", or "if sprinkled with sugar [then] like an ordinary grapefruit, harvested perhaps a bit too early".