JulieCraves

Research on coffee growing

Coffee leaf rust: a complex disease

Coffee leaf rust in Bolivia. Photo by Neil Palmer (CIAT).

Coffee rust (Hemileia vastatrix) is fungus that is one of the most devastating coffee diseases in the world. Native to Africa, it is now present in every coffee-growing nation. Infected leaves drop off, weakening the plant. Copper-based fungicides can be effective against coffee rust. However, it must be on the leaf surface to prevent infection, and copper can build up in soils, eventually reaching toxic levels.

The spores of coffee rust are spread by wind or rain, and will only germinate when exposed to one to two days of continuous wetness. Usually humidity is not enough; rain provides the necessary conditions.  Latin America has suffered through more frequent and prolonged rainy periods in recent years as have parts of Asia, thought to be due to climate change. As a result, coffee rust has been having increasing detrimental effects on coffee production.

Aside from fungicide application, there are two lines of defense against coffee rust: planting resistant hybrids, and modifying cultivation methods.

When coffee rust first arrived in the New World, around 1970 in Brazil, nearly all coffee being grown commercially was genetically nearly identical and very susceptible to rust. Thus, the development of rust-resistant hybrids has been an important element in battling this disease. Rust fights back, of course; there are over 40 strains of coffee rust, some of which now attack previously-resistant hybrids.

Colombia has made a large investment in “renovating” the nation’s coffee farms by swapping out older coffee varieties with rust-resistant types. This has been accomplished on a third of Colombia’s coffee lands so far. Some of the resistant varieties include Castillo, Tabi, and Colombia. One thing they all have in common is parentage that includes Hibrido de Timor, which in itself is a natural hybrid between arabica coffee (Coffea arabica) and robusta coffee (C. canephora).

Reliance on selective breeding and fungicides have more or less dominated the fight against rust, because there is debate about which cultivation method, sun or shade, helps mitigate this disease. This is in large part because the various factors that influence the severity of coffee rust outbreaks can be influenced, sometimes dramatically, by microclimate. This makes farm-wide management decisions tricky. Some examples of the quandary:

  • In full sun, plants dry out faster, hindering the germination and spread of rust, and sun may kill the fungus. However, pores (stoma) on the surface of leaves open up at high levels of light intensity, allowing more frequent and deep penetration of rust spores that are present.
  • Coffee grown in sun (especially if generously fertilized, as is usually the case) produces heavy yields. This over-bearing stresses the plants and makes them more apt to succumb to rust and other diseases.
  • Shade increases the life of leaves and their size, so rust spores have more leaf area to colonize and time to be dispersed.
  • Coffee types that are less genetically resistant to rust show lower levels of infection at lower levels of light intensity.
  • Shade trees intercept raindrops in gentle rains, so spores are not dispersed. In heavier rains, however, larger drops of rain accumulate and splash on the coffee, releasing many spores.

One very interesting bit of research suggests that growing coffee under shade can facilitate complex ecological connections that help fight coffee rust in Latin America. Green coffee scale (Coccus viridus) is a small insect that has many hosts, including coffee (on which it is usually more of a nuisance than a pest). Like many scale insects, it has a mutalistic relationship with some species of ants. The ants feed on “honeydew,” a sweet substance exuded by the scale insects. In exchange, the ants defend the scale insects from predators.  Meanwhile, green coffee scale can be infected with a fungus (Lecanicillium [Cephalosporium] lecanii) …which also attacks coffee leaf rust. Researchers have found that where green coffee scales are protected by a particular common species of ant (Azteca instabilis) which nests primarily in the shade trees, the scale insects reach localized population levels that enable the Lecanicillium fungus to attack the coffee rust.

Although not conclusive, this study suggests that shade coffee systems may provide some level of biological control over coffee leaf rust, and in fact this ant-scale-fungi relationship may be one reason rust was not as devastating in the New World as it was in the Old World. (The ants, scales, and fungi are only part of this very complicated system, which also includes a decapitating fly, wasps, and a lady beetle; see Vandermeer et al. 2010 for more fascinating details.)

Avelino, J., Willocquet, L., & Savary, S. (2004). Effects of crop management patterns on coffee rust epidemics Plant Pathology, 53 (5), 541-547 DOI: 10.1111/j.1365-3059.2004.01067.x

Vandermeer, J., Perfecto, I., & Liere, H. (2009). Evidence for hyperparasitism of coffee rust (Hemileia vastatrix) by the entomogenous fungus, Lecanicillium lecanii, through a complex ecological web Plant Pathology, 58 (4), 636-641 DOI: 10.1111/j.1365-3059.2009.02067.x

Vandermeer, J., Perfecto, I., & Philpott, S. (2010). Ecological Complexity and Pest Control in Organic Coffee Production: Uncovering an Autonomous Ecosystem Service BioScience, 60 (7), 527-537.

Fair and Direct Trade

Sips: Fair Trade debate

There are so many great voices in the fair/Fair trade movement, I keep out of it aside from environmental aspects of certification and occasional links. Here are a few of those links to some posts I have found most thought-provoking lately. Fair Trade is having growing pains, and recent high market prices for coffee have added to the turmoil.

The Stanford Social Innovation Review is a publication of the Center on Philanthropy and Civil Society at Stanford University. They recently ran two pieces on Fair Trade. The first, is The Problem with Fair Trade Coffee, by Colleen Haight, an assistant professor at San Jose State University. About a third of the way down is a good illustration of the author’s interpretation of why Fair Trade coffee has a “quality problem.” Lots of history and stats in the piece, and excellent comments, as well.

They followed up with a rebuttal from Fair Trade USA head Paul Rice, Fair Trade: A Model for Sustainable Development.

Meanwhile, Small Farmers. Big Change the blog of Equal Exchange, an alternative trade organization, also put out two pieces. Fair Trade is NOT the End Goal: Part I and Part II. Part I explained the pressures on co-ops during periods of uncertain high market prices, and the choices they face when it is time to deliver on pre-negotiated contracts which will pay less than the market price. One passage struck me,

When the coffee starts coming in, the competition (in the form of multi-national businesses) is knocking at the farm gates offering farmers more money for their beans than the price the co-op has promised them.

I added the emphasis. I suppose anybody could come along and offer higher prices at the farm gate, but look who is specifically singled out* as the entity who is trying to get  farmers to break their contracts with their co-ops: corporate coffee. As the post explains, this far-reaching problems. And those multinationals won’t be at the farm gate when prices drop again.

Part II is a view of the future of Fair Trade by Santiago Paz, co-manager, CEPICAFE, a co-op in Peru.

Food for thought.

*Update: A Wall Street Journal article, “Battle brewing over coffee” published on 17 July confirmed it is the “cash flush” multinationals tempting the farmers. The first sentence reads, “Rising prices have upended the coffee trade, as multinational brokers increasingly woo farmers away from local cooperatives in the world-wide scramble for beans.” It specifically mentioned these are representatives from  Nestlé SA,  ED&F Man Holdings Ltd.,  and Ecom Agroindustrial Corp. Ltd. The latter two are very large organizations that include coffee divisions (ED&F Man’s is Volcafe) that buy coffee for multinational roasters. These companies say that it’s up to the farmers who to sell to.

That’s true, and I can’t really blame the farmers, who need the cash. But these multinationals won’t be providing loans and support when coffee prices drop, and if the cooperatives go under, nobody will.

Maybe these high prices wouldn’t be as tempting if we’d been paying the real cost of coffee all along, providing a price that reflects all the work that goes into growing coffee, and enough for farmers to cover their costs of production and feed their families, send their kids to school, and invest in their farms and communities.

There is no such thing as cheap coffee.

Update #2: Fairtrade International (FLO) has been holding workshops on risk management and contract negotiation for cooperative managers to help them with the problems surrounding defaults on their contracts. FLO reports that Bolivia, Peru and Indonesia were the countries hit hardest by co-op member defaults. Read more here.

Photo by Ian Murchison under a Creative Commons license.

Climate change

Two degrees up

The International Center for Tropical Agriculture (CIAT) produced a series of short films on what a changing climate could mean for farming communities in East and West Africa, and South America. The segment below is the impact on coffee producers in Colombia — not only what changing climate could mean, but what it does mean already.




This film is also available in Spanish. The other films in the series chronicle land conflict and rural displacement in Ghana and water scarcity in Kenya.

Climate change

Mitigating climate change with coffee

The Decision and Policy Analysis (DAPA) Program of the International Center for Tropical Agriculture (CIAT) recently released results from a research project on mitigating climate change in Mesoamerican coffee production. You can download a PDF of the report, The Potential of Mesoamerican Coffee Production Systems to Mitigate Climate Change. This document is actually the thesis project of a Dutch student. The paper is a straightforward look at the how different shade coffee systems store carbon and their levels of greenhouse gas emissions, as well as how a few certifications (organic, Rainforest Alliance, UTZ Certified) influence those metrics.

Here are two slides from a presentation to whet your appetite (click to enlarge).

Traditional rustic shade has a larger carbon footprint than commercial polyculture because yields are lower per unit area, and all the contributing factors are allocated to less product. Note that biomass (below 0 on x-axis) denotes “credit” subtracted from factors that add to the carbon footprint.

Certifications other than organic don’t do much to reduce carbon footprint over conventional farming, suggesting that standards need to be modified to encourage footprint-lowering practices. Note that biomass (below 0 on x-axis) denotes “credit” subtracted from factors that add to the carbon footprint.

For an explanation of these interesting graphs take a look at the full report.  While it is over 100 pages, it is not a difficult read and I especially encourage people to take a look at page 68, which outlines coffee production practices that result in lowered greenhouse gas emissions, and page 70, which gives overall conclusions.