# Tropical race 4

By [lauren0w3](https://paragraph.com/@lauren0w3) · 2021-10-29

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[Tropical race 4](https://en.wikipedia.org/wiki/Tropical_Race_4) (TR4), a reinvigorated strain of Panama disease, was first discovered in 1993. This virulent form of fusarium wilt destroyed Cavendish in several southeast Asian countries and spread to Australia and India.[\[102\]](https://en.wikipedia.org/wiki/Banana#cite_note-karp-102) As the soil-based fungi can easily be carried on boots, clothing, or tools, the wilt spread to the Americas despite years of preventive efforts.[\[102\]](https://en.wikipedia.org/wiki/Banana#cite_note-karp-102) Cavendish is highly susceptible to TR4, and over time, Cavendish is endangered for commercial production by this disease.[\[103\]](https://en.wikipedia.org/wiki/Banana#cite_note-IBS-103) The only known defense to TR4 is genetic resistance.[\[102\]](https://en.wikipedia.org/wiki/Banana#cite_note-karp-102) This is conferred either by [RGA2](https://en.wikipedia.org/wiki/RGA2), a gene isolated from a TR4-resistant [diploid](https://en.wikipedia.org/wiki/Diploid) banana, or by the [nematode](https://en.wikipedia.org/wiki/Nematode)\-derived Ced9.[\[104\]](https://en.wikipedia.org/wiki/Banana#cite_note-Dale-et-al-2017-104)[\[105\]](https://en.wikipedia.org/wiki/Banana#cite_note-ISAAA-Dale-2021-105) Experts state the need to enrich banana [biodiversity](https://en.wikipedia.org/wiki/Biodiversity) by producing diverse new banana varieties, not just having a focus on the Cavendish.

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*Originally published on [lauren0w3](https://paragraph.com/@lauren0w3/tropical-race-4)*