JulieCraves

Coffee and the environment / Organic coffee

Pesticides used on coffee farms, part 3: Common pesticides

(Updated) Even though many chemicals that have been found to be harmful to the environment have been banned or are strictly regulated in the U.S. or Europe, they remain legal to use in less-developed countries, including many countries that grow coffee (a 2016 documentary, Circle of Poison, covered this topic).  This is troubling on many levels, beyond the fact that dangerous chemicals are being applied to crops.

For instance, workers in these countries may be less likely to be well-informed about the dangers of the chemicals, less likely to be provided with protective gear, and less informed about proper application methods (see this abstract, for example).  These regions are also much higher in biodiversity and ecosystem complexity, increasing the risk to the environment.

Here are just some of the more common chemicals used on coffee farms to control major pests and pathogens (which were described in a previous post).  I’ve included the World Health Organization classification, based on human risk.  Click on the link for more information.

Endosulfan (brand name Thiodan) — used against coffee cherry borer. (UPDATE:  As of early 2011, Endosulfan has now been slated to be banned globally, although it does not take place immediately. Here is a 2016 article about its continued use around the world.) Does not dissolve readily (but does degrade) in water and sticks to soil particles, so may take years to completely break down. Its breakdown products are more persistent than parent compounds. It is toxic to mammals, birds, and fish. Effects the central nervous system, and in animals causes kidney, testes, and liver damage. Class II (moderately hazardous). In Colombia, more than 100 human poisonings and one death were attributed to endosulfan use in coffee during 1993; more than 100 poisonings and three deaths were reported in 1994.  Here is an article on growing coffee without endosulfan.

Chlorpyrifos (brand name Dursban). A broad spectrum organophosphate used against coffee cherry borer and coffee leaf miner. In the U.S., the Environmental Protection Agency banned most household uses in 2000.  It is a contact poison.  It has caused human deaths, and has been linked to birth defects. It is extremely toxic to birds, freshwater and marine organisms, bees, and other wildlife.  It can bioaccumulate and effect bird reproduction. Class II. An article about chlorpyrifos is here.

Diazinon (brand name Basudin). Used against coffee borer. Not very toxic to mammals unless inhaled, it is nonetheless highly toxic to wildlife and beneficial insects, and acutely toxic to birds.  In the U.S. where it is still commonly used on turfgrass, diazinon has caused the second largest number of total known incidents of bird mortality of any pesticide. Class II. Another profile here, and a Sierra Club Canada fact sheet here.

Disulfoton. A systemic organophosphate insecticide used against leaf miner.  In the U.S., restricted use due to its high toxicity to mammals by all routes of exposure.  It is also highly toxic to birds and fish. Secondary exposure and poisoning occurs after birds feed on insects that have consumed residue-laden plants; these insects are impaired by the disulfoton and are easier for birds to capture, compounding the problem. High levels of toxins can be attained in this manner and has resulted in avian mortality in connection with disulfoton use.  It is delivered in granular form, which poses the threat of runoff and contamination of other crops when applied on slopes, on which coffee is often grown. Degrades or is metabolized by plants into harmful compounds that are very persistent in the environment. Class 1a, extremely hazardous (highest toxicity).

Methyl parathion (a.k.a. ethyl parathion, parathion). Organophosphate used against leaf miner. One of the most toxic pesticides,  highly restricted in U.S. Very toxic to birds when ingested or through skin exposure.  Also highly toxic to animals and fish. Persistent in soil and will bioaccumulate.  Areas sprayed with this chemical should not be entered for 48 hours. It is banned in Indonesia and restricted in Colombia, but Pesticide Action Network reports that there is evidence that methyl parathion is not used safely in Central America and is regularly misused in developing countries. Class 1a, extremely hazardous.

Triadimefon (brand name Bayleton). Copper-based fungicide used to against coffee rust. Only slightly toxic to birds, little is known about its effect on humans, but it is suspected that there is potential for reproductive problems with chronic exposure.  It has been found to induce hyperactivity in rats. The major concern is that long-term use of this and other copper-based fungicides is copper accumulation in soils, such as been found in coffee farms in Kenya and in Costa Rica.  Copper toxicity has been found in other crops grown in these soils, and copper impacts other biochemical and biological processes in soil, and little is known about long-term effects in tropical ecosystems. The primary metabolite of triadimefon is triadimenol, which is Class III (slightly hazardous).

Cypermethrin. A synthetic pyrethroid used against coffee cherry borer. Generally low direct toxicity to birds, but ingestion via contaminated insects causes mortality in young birds.  Extremely toxic to fish other aquatic organisms, and should not be applied any place where it may drift into water.  Class II.

Next in this series: Resources on organic coffee, and further reading.

Background information / Coffee and the environment

Pesticides used on coffee farms, part 2: Common coffee pests

Coffee is equipped with an excellent defense against herbivory: caffeine. Caffeine is one of many alkaloids that evolved in various plants to prevent them from being eaten by insects.  Evolution doesn’t stand still, however, and some insects have fought back. Coffee is attacked by several pests and diseases. Here are the most important, the ones that are most frequently combated with pesticides.

Coffee cherry/berry borer or “Broca” (Hypothenemus hampei). Native to Central Africa, but now found in many coffee-producing nations. The female of this tiny beetle (shown here on a green coffee bean) bores into the coffee cherry and lays about 15 eggs; the larvae feed on the developing bean. Usually, the cherry drops from the tree. The best defense is making sure there are no unpicked beans left on the trees or laying on the ground. Because they spend much of their life inside the cherry, controlling borers with insecticides can be difficult or downright ineffective.

Coffee leaf miner or “bicho mineiro” (Leucoptera coffeella). The leaf damage from the larvae of this small moth means less leaf surface is available for photosynthesis, resulting in stunted plants and reduction in yield. Native to Africa, but now found in many coffee-producing nations. This insect has developed resistance to insecticides in some areas.

Other insect pests include root nematodes (Meloidogyne spp.), green scale (Coccus viridis), and twig borers (Xylosandrus compactus).

Although not an insect, the next pathogen also prompts chemical onslaughts:

Coffee leaf rust (Hemileia vastatrix). A fungus that causes yellow spots on leaves, reduced photosynthetic ability, and eventually leaf drop. This causes a lack of nutrients going to growing shoots, and so can impact future growth of the plant. Spores require rain to germinate (high humidity is not adequate). Disease spreads more quickly in dense plantings and is less severe in shaded plantings, as the spores require a certain light intensity to germinate. Temperatures at farms at higher elevations are often too cool for the fungus.  Native to Africa, but now found in many coffee-producing nations. Some coffee cultivars have resistance, notably the catimor variety, and also catuai and mundo novo.

Next in this series: Common pesticides used on coffee farms.

Coffee berry borer on bean photo by P. Greb.

Organic coffee

Pesticides used on coffee farms, part 1: Introduction

Coffee is an agricultural crop and like any other crop, when it is grown for commercial production at any large scale, farmers seek a way to maximize output.  Often this means via the use of chemicals. These can be categorized into three broad groups: non-organic fertilizers, herbicides, and pesticides.  This is the introduction a three-part series on pesticides in coffee.

Testing of green coffee beans contracted by the Natural Resources Defense Council detected traces of many agricultural chemicals.  The high temperature of roasting reduces or eliminates many of these chemicals, but the primary concern regarding these toxins is how they effect the health of the coffee farmers who apply them, the surrounding communities, and their often severe impact on wildlife and ecosystems.

In this series, I will cover common pests and pathogens of coffee, the most common chemicals used on coffee crops for pest control and their effect on people and the environment, and finally information and resources on organic coffee and pesticides and birds.

Birds and other biodiversity / Research on coffee growing

Research: Biodiversity and profitability in coffee agrosystems

Gordon, C., R. Manson, J. Sundberg, and A. Cruz-Angon.  2006. Biodiversity, profitability, and vegetation structure in a Mexican coffee agrosystem. Agriculture Ecosystems & Environment 118:256-266.

This study looked at coffee grown in various types of shade in central Mexico, and any correlation between biodiversity (in birds and mammals) and profits. The conversion of plantations to sun coffee is generally believed to increase yield (and therefore profits), while the preservation of shade and forest tree species is thought to be costly in terms of decreased yield.  However, the additional costs of chemical inputs and labor in sun coffee may offset any increases in yield.  This study sought to examine this purported trade-off.

They found no support for a trade-off between biodiversity and profitability. Biodiverse, large shade plantations were highly profitable under all price scenarios, even profit calculations did not include any price premiums, such as those received if a farm is certified organic.  The authors concluded that farms and the environment both stand to gain…

“…by dispelling the notion that high-input, low biodiversity and sun and specialized shade coffee cultivation systems are the most economically sensible ways to grow coffee.”

Sites that were shade monoculture (or “specialized shade”) — with a low diversity and density of shade trees — were indistinguishable from sun coffee in terms of abundance and diversity of forest birds.  This emphasizes the point that not all shade coffees preserve biodiversity. These farms have shade trees, could market their coffee as “shade grown,” and may appear to non-biologists as having a lot of birds (which tend to be common, open-area generalists like grassquits and sparrows), but really do not preserve the diversity of species that were present before the native forest was cut down.

Many farmers have the erroneous belief that epiphytes parasitize shade trees, and they remove them. Biodiversity and profitability could immediately increase if farmers stopped this practice (called “destencho”). See this post on the value of epiphytes in coffee farms. Compared to intact forest, even the shaded farms lacked a number of bird and mammal species, in particular those that utilize the understory and ground level.  These are the layers most managed and disturbed in coffee farms.  Diverse shade coffee farms are best at preserving species that live in the upper layers and canopy.