Coffee Leaf Rust kills the plant slowly, and harms coffee taste quality while doing it.
The results from the GuatemalaGuatemalan coffee is considered a top quality coffee producer in Central America. Due to our proximity to Guatemala, some of the nicest coffees from this origin come to... coffee harvest this year (2013) will be a study in extremes; great coffees from some farms, and serious quality issues from others. While some areas seem to have good volume of coffee on the trees and nice quality, others zones are being devastated by a coffee fungus called RoyaCastillo is a selection of the Colombia cultivar that has become the most commonly grown coffee in Colombia. It is preferred to the older resistant variety, Variedad Colombia....
Roya affects coffee at lower altitude and more wet, humid microclimates but it is so vigorous this year it appears nearly everywhere in Central America, from PanamaPanama coffee ranges from medium quality lower altitude farms to those at 1600 - 1800 meters centered in the area of Boquete in the Chirqui district near the... to MexicoMexican coffee originates from South-central to Southern regions of the country. For that reason, coffees from Coatepec and Veracruz are much different from Oaxacan Plumas, which are in..., from the lower 1000 meter HB grade farms to 1500 meter SHB ( Strictly Hard BeanA classification used in some countries in Central America (Guatemala, Costa Rica) indicating the coffee was grown at an altitude above 1200 feet/4000 meters: In Costa Rica, a...) altitudes, and up to the highest 1800 meter growing areas. Roya is a leaf fungus which affects other crops as well ( corn, rice, etc) and is controlled mostly by the use if fungicides. In coffee, Roya causes leaf drop and will slowly kill the plant. If the coffee shrub has the energy to produce coffee fruits, it will often fail to ripen them; cherries will turn from green to yellow and then simply fall from the tree.
Roya can be controlled but not eliminated, but requires 3-6 spraying treatments per crop with products with names like Amistad (freedom). This has a high cost in terms of labor and the product itself. Simply spraying is not enough. Other controls are critical, mainly cutting back any shade trees to allow more sunlight to pass through, and cutting back the coffee itself to allow air and light to circulate, as well as give the plant a chance to recover from producing fruit. The chemicals are expensive, and while not desirable, they are used in a controlled and localized way. In other words, you wouldn’t see wholesale application of chemicals as might happen in mechanized farming and other types of crops.
Advanced stage Roya Coffee Leaf Rust CLR 
At Rama, they have many trees suffering from Antracnose, Dieback Fungus, and types of leaf fungus, like coffee leaf rest. Here’s a picture of some ripe fruit along with the leaf that has CLR. The advice was to wait until the fruit was more ripe to harvest, and I was showing them the type of fruit we like to see packed. 
Roya fungus, or Coffee Leaf Rust ( CLR ) can be found on other plants around a coffee farm. In this case some clover of some kind. I have seen it on corn too. It likes any broad leaf plant.
The knowledge of how to fight Roya, and the money for fungicide, the labor to treat it, and to cut back the trees deals a huge blow to the income and profits of the coffee farm. The real impact is on organicGrown without the use of artificial fertilizers, herbicides, etc.: Organic coffee has been grown according to organic farming techniques, typically without the use of artificial fertilizers. Some farms... farms, whether certified farms or organic-by-default farms, on casual coffee farmers who have little technical knowledge, and on smallholder farms in general. In a couple crop cycles, Roya unmanaged is the death of the coffee farm.
On my trip to Guatemala last week, I had a good overview of how Roya is affecting the current harvest and the future ones as well. In the high areas of Huehuetenango, I saw good quantities of fruit on the trees up at 1700 and 1800 meters, and even the low farms as 1200 meters planted in BourbonA coffee cultivar; a cross between Typica and Bourbon, originally grown in Brazil: Mundo Novo is a commercial coffee cultivar; a natural hybrid between "Sumatra" and Red Bourbon,... (which is not Roya-resistant ) looked pretty good. I saw more of a different fungus, Ojo de GayoGayo is ethnic group from the area of Aceh Sumatra around Lake Takengon. They use the name Gayo Coffee to market their production. The Acehnese are a different..., as well as Antracnosis, than coffee rust disease. In cuppingCupping is a method of tasting coffee by steeping grounds in separate cups for discrete amounts of ground coffee, to reveal good flavors and defects to their fullest.... the Huehuetenango coffees there was every indication there will be some beautiful offerings, but that cold weather and rains are making the fermentationFermentation in coffee processing traditionally referred to the stage in wet-processing of the coffee. We now understand that fermentation happens more broadly in nearly all processes, including honey... and drying difficult. Cup quality issues were mostly related to those processingThe removal of the cherry and parchment from the coffee seed.: Coffee is either wet-processed (also called washed or wet-milled) or dry-processed (also called wild, natural or natural... defects.
High farms in Antigua that we visit, like Cabrejo, have slight signs of Roya, but in general the coffee shrubs are leafy and loaded with cherryEither a flavor in the coffee, or referring to the fruit of the coffee tree, which somewhat resembles a red cherry.: Either a flavor in the coffee, or.... Acatenango is again badly affected, as it was last year. Some farms will produce half of what they did two harvests ago. There are some zones in Acatenango at higher altitudes that are relatively unscathed, so we expect great shipments from the farms we work with. But these higher grown coffees aren’t ready for cupping yet.
It was in the San Juan Alotenango area I saw the drama of Roya unfold. At the large and well-managed La Candelaria, the harvest was good and quality is far better than last year. But this comes at an immense cost that only a technically proficient and well funded farm can bear. Every tree on the farm is already a techniques plant that is bred to survive disease, since the farm had a huge problem with nematodesIn coffee agriculture, nematodes as a pest affect the root of the coffee, attacking the plant. There are also beneficial types of nematodes that add to soil health.:... from before. The CaturraCatimor is a broad group of cultivars derived from a Hibrido de Timor (HdT) and Caturra cross, highly productive, sometimes with inferior cup flavor. The main issue is... and Bourbon coffees, the Villa SarchiAn arabica cultivar that is a natural dwarf mutation of Bourbon, and in that way is similar to Caturra (as well as Pacas). and Bourboncito varieties …all have been grafted to robustaAteng is a common name for Catimor coffees widely planted in Sumatra and other Indonesia isles.: Ateng, with several subtypes, is a common name for Catimor coffees widely... root stock that can resist the effect of nematodes.
Above ground, the plants received 6 fungicide treatments and every third row has been reduced to a hip-hip high “skeleton” cut that will take it out of production for the next harvest. All the Gravillea and Inga leguminous shade trees have been trimmed or replaced with smaller plants to reduce shade. Most any farmer but for the well-trained would be so proactive against the Roya plague, but it is exactly what is required because once Roya takes hold of a farm, it is too late.
Across the way from Candelaria, are small holder farms we buy from on the incline up to the top of Volcan Fuego. While there were some small farmers who treated with 2 or 3 spray sand still had more than a few leaves on their coffee, most little plots of coffee were devastated. The young plants that would normally be in the flush of life were like spindly wood stakes in the ground, a paltry crown of a few discolored leaves fluttering in the wind like the flag of death, than any sign of future hope.
As with most disasters, it will be the poor and unprepared who suffer the most. The little farms I saw that were most affected aren’t the sole income of the farmers, so it’s not that they are being pushed off an economic cliff. But it is going to hurt badly. NicaraguaNicaraguan coffees from the Segovia, Jinotega, Ocotal and Matagalpa regions are nice balanced cups. They often possess interesting cup character along with body and balance, outperforming many other... announced their intention yesterday to create an “army” of 15,000 agronomists, trained farmers and volunteers to educate about the treatment of Roya and to distribute materials with which to fight it.
It appears that the next civil war in Central America will be fought in the fields, but in this case the enemy is no less threatening to the livelihood of the rural farmer than the conflict of the 1980s and 1990s
– Tom, from Antigua Guatemala 2013
