Plant Health Week – day 1

So far my blog has been dominated by coronavirus and its spread and control, but there are other topics that are almost as important for our well-being. This week we are celebrating #PlantHealthWeek, part of the International Year of Plant Health 2020 #IYPH2020. To mark this occasion I hope to write a post each day, to give you, my readers, an idea of how important plants – and plant pests – are to our lives and to mention data and statistics.

Back in the early 1990s, I was a young post-doc in Cambridge who had just started working in the Department of Plant Sciences. Our Common Room (for those not familiar with the University of Cambridge, this is a room where we gathered for our regular tea and coffee breaks) was decorated with portraits of all Botany Professors from 19th century onwards. One painting was showing a rather imposing looking man with a really big moustache, Harry Marshall Ward (1854-1906; Professor of Botany 1895-1906).

In mid-1800s coffee was grown in Ceylon (modern Sri Lanka) and the British plantation owners planted a monoculture of coffee trees on almost every available piece of land. In the 1860s a disease, coffee rust, was spreading in the plantations, killing the trees. Leaves will develop yellow patches, the plant will be unable to produce food and the trees will start to die. The production dropped from 45,000 tons in 1870 to 2,300 tons in 1889.

Mycologists Michael Joseph Berkeley and Christopher Edmund Broome discovered that the disease was caused by a fungus and they named it Hemileia vastatrix – the first part of the name reflecting a half-smooth shape of “spores” i.e. little “seeds” by which the fungus spreads, and “vastatrix” meaning a “she-destroyer”.

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Ward came to Ceylon in 1880 to help find the cure for the coffee rust. He recommended avoiding monoculture by growing different types of coffee. He also pioneered “agroforestry” – growing coffee under trees to stop spores being flown by the wind. Growing coffee trees – which are quite small – together with tall trees is practised now as this helps to maintain the right microclimate and shielding from strong sun, as well as providing additional income from timber.

Ward did not manage to solve the Ceylon problem with the coffee rust and the coffee industry there was completely devastated. In order to find a replacement, plantation owners started growing tea which then became the famous Ceylon tea. The English tradition of drinking tea apparently has its origin at that time.

The coffee rust did not stop there and over the years spread throughout the world. There is a constant race between breeding new resistant coffee varieties and the pathogen overcoming the barriers, and between finding new pesticides and the fungus finding ways to resist them. Coffee rust, La roya, is a huge problem across the globe, causing multiple economic and social tragedies.

By the way, I still have not figured out how Professor Ward managed to drink or eat with his moustache…