ProMED
http://www.promedmail.org

Source: Reuters [abridged, edited]
https://www.reuters.com/lifestyle/science/colombia-warns-nine-new-strains-dangerous-coffee-fungus-2021-04-30/

Colombia's coffee federation has discovered 9 new, more aggressive variants of the fungus that causes coffee rust. Since 1983, when rust was first detected in the country, the National Center for Investigations of Coffee (Cenicafe) has identified 22 varieties of the rust [see, for example, ProMED posts 20100526.1745, 20091008.34... , 20090225.0773]. "I call on producers to build or renew their crops with resistant varieties, using certified seeds," the federation's Roberto Velez said in a statement. In Colombia, the climate and altitude of coffee crops are favorable for coffee rust, Cenicafe said.

Coffee rust is present in all producing countries and can cause losses of between 30% and 80% in susceptible plant varieties when outbreaks are not managed quickly. Resistant varieties account for just over 84% of Colombia's coffee crops, with susceptible varieties making up the remaining 16%. Regular measurements show that while the average incidence of rust in susceptible varieties is 20% or more, it is 6% or less in resistant varieties.

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ProMED
<promed@promedmail.org>

[Coffee leaf rust (CLR; also called orange rust) is caused by the fungus _Hemileia vastatrix_, one of the most feared pathogens of the crop. Of the 2 coffee species grown commercially, _Coffea arabica_ (arabica or highland coffee) and _C. canephora_ (robusta or lowland coffee), CLR affects only arabica varieties, which are usually preferred for their taste. The rust has completely destroyed coffee industries in several countries. The disease is characterised by yellow-orange powdery lesions on the underside of leaves, where it attacks through stomata, but it rarely occurs on stems or fruit. CLR can lead to complete defoliation with death of the host plant.

Rust spores are spread by wind, rain and mechanical means. Disease management relies mainly on multiple fungicide applications during the rainy season. Rust-resistant cultivars exist, but the crop is generally of poorer quality. More than 30 races of the fungus have been detected, making it particularly difficult to establish durable host resistance.

Coffee leaf rust (CLR; also called orange rust) is caused by the fungus _Hemileia vastatrix_, one of the most feared pathogens of the crop. Of the 2 coffee species grown commercially, _Coffea arabica_ (arabica or highland coffee) and _C. canephora_ (robusta or lowland coffee), CLR affects only arabica varieties, which are usually preferred for their taste. The rust has completely destroyed coffee industries in several countries. The disease is characterised by yellow-orange powdery lesions on the underside of leaves, where it attacks through stomata, but it rarely occurs on stems or fruit. CLR can lead to complete defoliation with death of the host plant.

Rust spores are spread by wind, rain, and mechanical means. Disease management relies mainly on multiple fungicide applications during the rainy season. Rust-resistant cultivars exist, but the crop is generally of poorer quality. More than 30 races of the fungus have been detected, making it particularly difficult to establish durable host resistance.

New fungal strains adapted to higher-altitude conditions, which may also show additional fungicide resistances, have emerged in Central America, making CLR control in the region considerably more difficult (for example, see ProMED posts 20170515.5038218, 20140604.2518313, 20120920.1301244). Generally, fungal spores that are wind borne or can easily be carried on travellers' clothes, as is the case for CLR, pose a very high biosecurity risk.

Maps
Colombia:
https://i.pinimg.com/originals/80/08/ab/8008abded64a61556a928c4f3388965b.gif and
http://healthmap.org/promed/p/16
South America, overview:
http://ontheworldmap.com/south-america/political-map-of-south-america.jpg

Pictures
CLR symptoms:
http://santaram09.files.wordpress.com/2010/01/coffee-leaf-rust.jpg,
http://dwpicture.com.au/photos/110363b.jpg and
https://www.newphytologist.org/blog/wp-content/uploads/2017/01/composite-fig.jpg

Links
Additional news stories:
https://wabx.net/2021/04/29/colombia-warns-of-nine-new-strains-of-dangerous-coffee-fungus/,
https://www.terra.com.br/economia/colombia-detecta-novas-variantes-da-ferrugem-do-cafe,52375405d18c1ae6fec555558d78b435zcpkj1yg.html (in Spanish), and
https://dailycoffeenews.com/2021/04/30/colombian-researchers-discover-aggressive-new-variants-of-coffee-leaf-rust/ (thanks to International Biosecurity Intelligence System)
Coffee leaf rust information and background:
https://bsppjournals.onlinelibrary.wiley.com/doi/10.1111/mpp.12512 (review),
http://www.extento.hawaii.edu/kbase/crop/Type/h_vasta.htm,
http://www.apsnet.org/edcenter/intropp/lessons/fungi/Basidiomycetes/Pages/CoffeeRust.aspx,
http://www.coffeeresearch.org/agriculture/hemileiavastatrix.htm, and
http://www.nature.com/news/coffee-rust-regains-foothold-1.12320
CLR resources via:
http://www.coffeeresearch.org/agriculture/rust.htm
_H. vastatrix_ taxonomy:
http://www.indexfungorum.org/names/NamesRecord.asp?RecordID=182962
Arabica coffee varieties:
http://www.coffeeresearch.org/agriculture/varietals.htm
Cenicafe:
https://www.cenicafe.org/
- Mod.DHA