The ourbreak of coffee disease called Coffee Leaf Rust aka Roya has been unstoppable pandemic throughout Latin America. Some say this year’s Arabica coffee crop will be reduced by over 30% and 50 to 60% for the next year.
Besides Coffee Leaf Rust, the coffee has several enemies, a political unstability, international competition, frosts, and droughts. Many of you may remember 1970s’ devastating black frost in Brazil. It severely affected the country’s harvest and coffee market for multiple years. However none was as destructive as Coffee Leaf Rust in the history of coffee.
What is Coffee Leaf Rust
Coffee Leaf Rust is caused by fungus called Hemileia vastatrix. The fungus spores land on coffee leaves and infect them. Reddish yellow spots appear on the underside of infected leaves. It spreads to other leaves and other trees. Infected leaves fall off the trees, and the trees which lost leaves die since no longer able to proceed photosynthesis. If the tree is recovered, crops can be expected next season, but a new tree doesn’t bring crops until it matures in 4 years.
What’s so destructive is that coffee leaves can be aerially infected with Roya. Roya spores fly in the air, and they land on leaves with rain. The fungus starts growing deeply within the cells in a leaf, and it goes into incubation. When the desirable temperature hits, it starts producing red-rusty-colored spores on the back of the leaf. There are several billion spores released from one infected tree. That’s how it spreads from one tree to the whole farm, to the district, and to the whole region.
In The History
It’s generally said that there were two major Roya leaf rust pandemics. The first one was in 1860s in South East Asia. The second one was in 1970s in Latin America.
The first Pandemic
The first documented appearance of Roya was around Lake Victoria in Kenya. It was in 1861, when the area wan’t developed yet. Seven years after the first appearance in Africa, it crossed the Indian Ocean and reached Sri Lanka, which was called Salon at that time. The coffee was brought to the area in 1658 by The Dutch East India Company. The full-scale commercial cultivation of coffee was started later after British took over the land by 1869. It spread to all over the Seylon island in a few years, and the severely destructed industry switched to the cultivation of the tea. Even so, at some mountainous region of the island, the original cultivars brought from Yemen survived, but they seemed to be replaced with newer anti-leaf-rust cultivars developed later in India.
In 1888, Coffee leaf rust finally reached to Java, one of the most developed coffee producing regions of the world at that time. At this time, most of Dutch rooted Typica cultivars were replaced with less valued Robusta(Canephora) coffee tree.
The Second Pandemic
While South East Asia suffered from the Coffee Leaf Rust, there was a region which was benefited from it. While Indonesia shifted to less appreciated Robusta coffee for it’s resistance to the disease, the South and Central Americas continued its Arabica coffee production.
However, in 1970, the first Coffee Leaf Rust was finally found in Brazil. It had been about hundred years since the first pandemic in Seyron. In about ten years, the Coffee Leaf Rust was reported in most of the coffee producing countries throughout Central and South Americas. The tragedy in Seyron converted the region’s industry from coffee to tea, but during the past hundred years, human came up with different solutions. One is a fungicide. The fungicide enabled coffee producers to avoid the massive wipe out of coffee in the farms. However, in order to reduce the agricultural costs, stopping the use of an expensive agricultural chemical was ideal for the growers. That’s how Leaf Rust resistant hybrid cultivars were widely adopted in South America.
In the early stage of commercial coffee production, the Arabica Typica was commonly cultivated. The search of Leaf Rust resistant cultivar started when the whole coffee farms in Ceyron were wiped out in late 19th century.
The first candidate was West Africa native Coffea Liberica, which is a different specie from commonly consumed Coffea Arabica. Soon after it’s discovery, in 1874, it was experimented in Indian Lab and determined that it is Coffee Leaf Rust Resistant. Liberica was planted in Java as a replacement of Arabica, but not long ater its adoption, Liberica was defeated by new strains of Leaf Rust.
Robusta(Canephora), found in the Central Africa in the end of 19th century, was revealed as an absolute Leaf Rust resistance after some experimental cultivation in Java.
However, the excellence in the Leaf Rust resistance doesn’t come with the excellence in its taste. Robusta could never have a decent match with Arabica in flavor. Robusta highlights strong bitterness and off-flavor. It is used for most of instant coffee and often as an espresso blend component.
In 1925, the Coffee Board of India was established in India, where the industry is in a crisis of the Leaf Rust, to pursue a new cultivar that is the Leaf Rust resistant. Kent is one of some remarkable Arabica cultivars developed in the process. This typica strained Kent is considered to be the oldest cultivar originated in India. Later, a natural hybrid of coffea Arabica and coffea Liberica was discovered in India, and crossbreeding S288 and Kent created a more fertile and Leaf Rust resistant cultivar, S795.
Furthermore, from around 1950s, many countries contributed to a journey seeking a Leaf Rust resistance from Ethipian heirloom species. In this journey, sampled heirloom cultivars counted several thousands including some Leaf Rust proof Agaro, Kaffa, and even the famous Geisha.
Those Arabicas showed some tolarence to the Leaf Rust, but they weren’t the perfect remedy.
In 1927, another Leaf Rust resistant coffee tree was discovered in Portuguese East Timor and revealed to be able to crossbreed with other Coffea Arabica. Later it’s found that this coffee is a hybrid of Robusta with chromosome aberration and coffea Arabica. Unlike normal Robusta-Arabica hybrid, this chromosome aberration that the Robusta carried enabled it to crossbreed with Arabicas. This hybrid was named Timor or Timor Hybrid. The Timor carries the characteristics of Robusta’s absolute Leaf Rust resistance, but much of improvement in a cupping quality wasn’t seen even in comparison to ordinary Robusta.
However the characteristic of this variety to be able to crossbreed with coffea Arabica took a significant role. The first practical cultivar was developed in Portuguese lab in 1959. Caturra, a Brazilian native Bourbon dwarf cultivar which was popular in Central America, and Timor was crossbred to produce Catimor, higher quality Robusta-Arabica Hybrid. Since 1970, this Catimor and other hybrids have been widely adopted throughout Central and South Americas.
In Colombia, Catimor was further mixed with Caturra, the Arabica cultivar, and it was called Variedad Colombia(or simplly Colombia).
In Brazil, Arabica dwarf cultivars as well as Caturra but rather better adopted to the climate, Villa Sarchi and Catuai were crossbred to create more Brazil suited cultivars, Sarchimor, Tupi, and Obata.
As the result of Hybrid Adoption in Central and South Americas, some say the quality of coffee from the regions decreased after 70s. In addition, the specialty coffee industry, developed as an antithesis of low grade coffee, seems to run counter to Hybrid cultivars. However, I’m not sure how many of the optimistic Arabica supremacists can boldly deny the necessity of Hybrid cultivars in the coffee industry during this recent Leaf Rust outbreak.