Exeter University: “No evidence climate change boosts coffee plant disease”

Coffee Beans

Coffee Beans. By Harald Hoyer from Schwerin, Germany (Coffee Beans) [CC BY-SA 2.0], via Wikimedia Commons

Guest essay by Eric Worrall

h/t Telegraph – the “end of coffee” climate scare story which has been circulating recently has just been exposed as nonsense by a new study from Exeter University.

No evidence climate change boosts coffee plant disease

Fears that climate change is promoting a fungal disease which can devastate coffee crops may be unfounded, research by the University of Exeter suggests.

Media reports have linked coffee leaf rust – also known as CLR or roya – with climate change, but the new research finds “no evidence” for this.

Researchers tested the hypothesis that “the weather was responsible for a recent outbreak of CLR in Colombia and that climate change increased the probability of weather conditions favourable to CLR”.

The paper, published in Royal Society journal Philosophical Transactions B, concluded: “We find no evidence for an overall trend in disease risk in coffee-growing regions of Colombia from 1990 to 2015, therefore, while weather conditions were more conducive to disease outbreaks from 2008 to 2011, we reject the climate change hypothesis.”

Colombian coffee production fell by about 40% from 2008-11, and this decline has been linked to a severe CLR outbreak across Colombia and neighbouring countries.

Dr Dan Bebber, lead author of the University of Exeter study, said there was a “perfect storm” of factors favourable for CLR at that time, including weather conditions and a decrease in fertiliser use due to price rises during the 2008 financial crisis.

“Farmers weren’t treating coffee bushes as they normally would, and this was probably one of the factors that led to the rise in CLR,” he said.

“The climate at the time was conducive to CLR but there had been earlier periods of similar conditions when there wasn’t an outbreak.

Dr Bebber and co-authors Sarah Gurr and Angela Delgado Castillo (a student on Exeter’s MSc in Food Security at the time of the research) found that Colombian coffee yields had been highly variable over time due to varying weather, the effects of disease, management and socio-economic factors.

Dr Bebber said more research was needed to fully understand the causes of the 2008-11 CLR outbreak, which caused hundreds of thousands of people to lose their jobs in coffee farms in Central America.

Temperature and leaf wetness are the most important determinants of infection risk for fungal plant diseases including CLR, which does not usually kill coffee bushes but can dramatically reduce the crop they produce.

The study was supported by University of Exeter alumnus Gerry Brown and his wife Clemencia Brown.

Date: 24 October 2016

Read more: http://www.exeter.ac.uk/news/research/title_548830_en.html

The abstract of the study;

Many fungal plant diseases are strongly controlled by weather, and global climate change is thus likely to have affected fungal pathogen distributions and impacts. Modelling the response of plant diseases to climate change is hampered by the difficulty of estimating pathogen-relevant microclimatic variables from standard meteorological data. The availability of increasingly sophisticated high-resolution climate reanalyses may help overcome this challenge. We illustrate the use of climate reanalyses by testing the hypothesis that climate change increased the likelihood of the 2008–2011 outbreak of Coffee Leaf Rust (CLR, Hemileia vastatrix) in Colombia. We develop a model of germination and infection risk, and drive this model using estimates of leaf wetness duration and canopy temperature from the Japanese 55-Year Reanalysis (JRA-55). We model germination and infection as Weibull functions with different temperature optima, based upon existing experimental data. We find no evidence for an overall trend in disease risk in coffee-growing regions of Colombia from 1990 to 2015, therefore, we reject the climate change hypothesis. There was a significant elevation in predicted CLR infection risk from 2008 to 2011 compared with other years. JRA-55 data suggest a decrease in canopy surface water after 2008, which may have helped terminate the outbreak. The spatial resolution and accuracy of climate reanalyses are continually improving, increasing their utility for biological modelling. Confronting disease models with data requires not only accurate climate data, but also disease observations at high spatio-temporal resolution. Investment in monitoring, storage and accessibility of plant disease observation data are needed to match the quality of the climate data now available.

Read more: http://rstb.royalsocietypublishing.org/content/371/1709/20150458

In my opinion this debunking of a climate myth which was promoted by the likes of the Fairtrade Charity undermines all claims about anthropogenic CO2 aggravating pest or fungus damage to food crops. Not only does it demonstrate how eager climate advocates are to pin any problem on their favourite bogeyman, it also demonstrates that current generation fungicides and pesticides are more than adequate for the job – providing they are correctly applied.

As to the future, we are currently in the midst of a biotech revolution – unprecedented control of plant and animal genetics, and next generation pest and fungus management technologies, are on the verge of commercial realisation. If current generation pesticides and fungicides ever loose their effectiveness, for any reason, there are plenty of better products and technologies in the pipeline.

EDIT (EW): Fixed the link to the Fairtrade story.

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30 thoughts on “Exeter University: “No evidence climate change boosts coffee plant disease”

    • No. Just being wrong is far, far more worthy than the current climate change non-science. When ether proved unnecessary, it was dropped (Occam’s razor). The present day lies, stupidly bad science, corruption of data, corruption of peer review, and intimidation of dissenters threatens to destroy the institution of science itself.

      • Considering the imprecision of genetic engineering that is “always” on the verge of something new that never quite materializes,it is not likely that GE will ever combat anything except natural systems that will supercede all GE systems and not promote “Monopolies” that only contaminate,destroy and eliminate the natural systems that operate as nature intended them to do.Man needs to go back to basics of hybridization to discover even better ways to combat plant diseases and other strong points to cross to achieve what Genetic Engineering will never quite get right,IF EVER.

      • Gary Hild’s right.

        The GE industry is a monopoly. A highly corrupt and criminial monopoly (“”Monopolies” that only contaminate,destroy and eliminate the natural systems that operate as nature intended them to do”).

        The benefits from GMOs mostly go to the corrupt GE industry and their associated profiteering government pawns such as the FDA but surely not to the public. It only does according to this cartel’s hype and propaganda which the gullible indoctrinated public at large and “journalists” disseminate blindly and ignorantly.

        Anyone who looks past this pro-GE propaganda will see that there has been a long history of ignoring and suppressing the real dangers of GMO foods from the biotech industry.

        One of the earliest cases that has demonstrated that fact is the infamous tryptophan disaster of 1989 where the FDA ignored the warnings of their own scientists about the real risks of GMOs, simply to protect the business interests of the GMO industry, which they’ve been colluding with for decades – see http://www.supplements-and-health.com/l-tryptophan.html

        The government-biotech industrial complex has the average person believing that they’re protecting their health. Yet, lying about real facts, denying real facts, or minimizing or ignoring real facts is not protecting or helping the public, it’s deceiving the public. That cartel also pays online trolls to denounce anti-gmo commentators and spread the corporate GMO hype.

  1. Biotech works under climate – soil conditions and under chemical input agriculture technology-irrigation. Natural variability in climate influence the biotech more than the naturally grown crops under such scenario. Coffee production fluctuations with natural rainfall variability.

    Dr. S. Jeevananda Reddy

      • I don’t know on what basis you made that observation!

        I carried northeast Brazil precipitation analysis and demarcated homogeneous zones in terms of natural cycles. Fortaleza precipitation data series presented 52 year cycle with sub-multiples [ this paper was published in Brazilian Journal]. Based on this analysis, I projected future pattern. This exactly fitted with the present drought conditions.

        I did similar analysis for Mozambique and Ethiopia as well for Botswana & South Africa.

        Dr. S. Jeevananda Reddy

  2. I remember reading – about 1950 – 1960 – that bananas were doomed by some disease. The future was grim.
    Scientific American explained it all.

    .

    • Yeah, there’s always some reason given for why the future will be grim. As far as I can make out, it’ll only be grim while the doom-mongers are still around. THAT’S where the problem is.

      • I think that the reason all these doom-and-gloom stories abound is that journalists and writers need ideas to write stories, and their publishers need people to buy them. Doom and gloom always garners attention, is pretty easy to write, and it sells. People pushing an agenda are very good at feeding ideas to writers and journalists.

    • The commercially popular banana’s from the 50’s’ish were driven to extinction by a fungus. Our current banana variety which we enjoy is at risk by another fungus which is not currently treatable.
      However, this is by no means climate related as even the banana grown in Icelandic green houses are also at risk from this untreatable fungus.

  3. Last week, I was discussing this very situation with my coffee roaster who sources some of his green beans directly from specialty farms in South America. NONE of the farmers he has dealt with has had any fall off in production and the price rises have been entirely due to increased demand.

    And FairTrade are an organisation that imposes Marxist management practices on to its licenced farms so they are too small to be efficient. The end result is that FairTrade farms earn less money for their owners and workers with the extra money paid by roasters (and hence consumers) ending up paying the FairTrade organisation operating costs and overheads.

  4. Congratulations to the authors would be in order. It must be very disappointing to test the existence of something that would hit the MSM headlines worldwide, and find that it doesn’t exist – in spite of (probably) significant pressure from others to find it. Yet such is science, and “non-existence” findings are genuinely important. I can think of a few other things they could usefully research…….

  5. “Colombian coffee production fell by about 40% from 2008-11, and this decline has been linked to a severe CLR outbreak across Colombia and neighbouring countries.”

    This is why I really dislike organic activism and organic produce from tropical regions especially. It is just cruelty to farmers.

    Organic Coffee Farmers in Central America May Not Survive

    Organic coffee farms in Central America have typically been located at high altitudes where there has been less worry about fungal disease. However, in recent years, fungal outbreaks have increasingly-occurred at these higher elevations and organic growers may not survive the huge yield losses due to their non-use of fungicides.

    “Finca Santa Isabel, often held up as a shining example of success with organic agriculture in coffee, may not make it. The culprit? A fungus known as roya that often goes unnoticed until bright-orange pustules start appearing on the underside of leaves. This parasite interrupts the tree’s ability to nourish itself by redirecting nutrients to those colorful lesions. Eventually, the infected leaves shrivel up and fall off.

    The Keller family owns Finca Santa Isabel, located in Santa Rosa, about an hour south-east of Guatemala City. It became the second estate to be Rainforest Alliance-certified in 1997, and the Kellers were named Sustainable Standard-Setter by the nonprofit in 2003. In a 2009 profile, the family was lauded for its successes with sustainable practices: caring for the land, being a profitable business, and having enough left over to help build needed infrastructure for their community. They grow Arabica at an elevation of 3,500 to 4,500 feet above sea level in a zone most growers thought roya could not thrive.

    But the rusk outbreak is happening almost everywhere. By most accounts, large and low-lying estates accustomed to spraying to protect their trees will survive. …Growers in areas prone to the rust use fungicide prophylactically twice a year. Spraying, which typically occurs in July and September in Central America, is timed to happen just before and just after periods of heavier precipitation.

    Farmers caught unprepared, like Keller, have to decide whether and how to fight this blight.

    The fungus is causing huge shortfalls in coffee cherries at higher elevations and in shaded areas of Central America, in places where growers used to feel relatively immune. Keller was one of them and he relayed a stunning loss: “Last year, we had about a 70% drop in production and so did many other farms that work conventionally around us. The main reason is that nobody thought that it was going to be so bad.”

    Guatemalan workers on coastal farms in lower altitudes that face the Pacific sprayed ahead of time. Farmers in these regions have also planted rust-resistant varieties as part of recovering from earlier outbreaks. Those growing coffee in hillier areas at higher altitudes did not. Nor do they use fungicides routinely.

    “…The pathogen itself could be adapting to temperature variation or it could be a combination of the weather events with growers not using fungicides making disease more severe.” ref:pesticideguy

  6. Fungicides Save Brazil’s Coffee Crop
    Posted on July 24, 2012 by pesticideguy

    Coffee leaf rust is considered one of the most catastrophic plant diseases of all time. In the 1860s, coffee rust was largely responsible for destroying the coffee plantations of Ceylon (Sri Lanka), which had been the greatest coffee-producing country in the world. As coffee rust spread through Asia and Africa, coffee production increased significantly in Latin America where coffee rust was not present. However, coffee rust was detected in Brazil in 1970 and has since spread throughout Latin America, making fungicide use essential.

    “In susceptible cultivars, chemical control has been the only option for decreasing the incidence of CLR on plants, and for reducing the harmful effects on the disease. The coffee growing regions in Brazil as well as almost all other coffee-producing regions worldwide are comprised of susceptible Coffea arabica and Coffea canephora cultivars (the latter is the second most widely cultivated coffee species). Preventive control of CLR in the main Brazilian coffee-producing regions consists from four to six applications of protective copper-based fungicides and two to three foliar applications of systemic fungicides.”

    Authors: A. Fernando de Souza, L. Zambolim, V. Cintra de Jesus Jr., P.R. Cecon.
    Affiliation: Federal University of Vicosa, Minas Gerais State, Brazil
    Title: Chemical approaches to manage coffee leaf rust in drip irrigated trees
    Publication: Australasian Plant Pathology. 2011. 40:293-300.

    Organic activists are pushing more and more for restrictions on fungicide use, and so is the EU. It is extremely important to stay out of all trade deals that come with foreign environmental regulations like restricting pesticide uses, such as TTIP.

    • Organic activists are pushing more and more for restrictions on fungicide use, and so is the EU. It is extremely important to stay out of all trade deals that come with foreign environmental regulations like restricting pesticide uses, such as TTIP.

      That is my own remark, not part of the original column.

      Please, where you see increases in rust, smut, scab, blight, mildew and such, consider the possible impact of organic growers, who refuse to control these diseases.

  7. It is reassuring to see that the lag time between the start of circulation of these bogus ‘Climate Change’ stories and their rebuttal by scientific studies is getting shorter and shorter.

  8. Which reminds me of a certain F. Sinatra singing “They’ve got an awful lot of coffee in Brazil”. Should perhaps now be “They’ve got a lot of awful coffee in Brazil”.

  9. thinks captain obvious. No climate change in coffee producing areas … it is just as awful (to me) as ever was.

  10. “The climate at the time was conducive to CLR”

    The weather at the time. 2008-2011 does not a climate make.

  11. “No evidence climate change boosts coffee plant disease”

    No evidence of (human-caused) climate change, either.

    • The globe started warming within decades of the first coffee house in England, Oxford’s Angel, in 1650.

      Coincidence? I think not.

  12. Coffee farmers have no problem with harvest, the less global production the higher coffee prices. And the ‘markets’ LOVE volatility.

    Problems are with workers on the fields; they should be used to.

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