Tackling wheat diseases to protect global food security

Prof Alastair Ager, DFID Deputy Chief Scientific Adviser, with Áine McGowan, DFID Agriculture Research Team

In an earlier blog post, I wrote about the great potential for new technologies to help us address some of the most difficult development challenges. I have been particularly struck by the scale of impact achieved through new technologies in our agricultural research investments. For this blog post, I teamed up with Áine McGowan from our Agriculture Research team to explore wheat research, and how it is helping poor farmers across Africa and Asia to protect their crops and livelihoods from the devastating impact of wheat diseases and climate change. We explore the benefits of this work for developing countries as well as for farming and food businesses here in the UK. Read on to the end to see a great video featuring British scientists explaining how UK aid supports the sustainability of wheat farming globally.

Wheat provides nearly 25% of the world’s calorie intake

Wheat matters. The crop feeds 1.2 billion people living in extreme poverty and provides almost a quarter of calories consumed worldwide.

However, for wheat farmers across North and East Africa, the Middle East and South Asia, wheat diseases are a constant threat. Some diseases can destroy entire fields of wheat in a matter of weeks. For farmers who rely on wheat as a source of food for their families and as an income stream, this can be ruinous. The most conservative estimates of losses to rust disease alone amount to USD $1.12 billion per year, mainly affecting smallholder producers.

Evolving crop killers

One reason that wheat diseases are so difficult to control is that they are very easily spread. The spores of the fungi responsible for wheat rust diseases do not respect international borders. They are blown thousands of kilometres by wind and can jump continents when accidentally carried on the clothing of people who are travelling internationally.

Not only that, they are constantly evolving. Stem rust was all but eradicated in the mid-twentieth century following a global effort to produce new disease-resistant varieties of wheat. However, a new aggressive strain of the disease — Ug99 — suddenly emerged from Africa in the 1990s. Because it could overcome the resistance bred into wheat, it has been able to spread rapidly across Africa, the Middle East, and into Europe in the decades since. This re-emergence of stem rust as a global threat demonstrates just how effectively wheat diseases can mutate, infecting crops that are only resistant to older strains.

So how can we control these diseases? Using fungicides to tackle wheat disease is more difficult than one might expect. Accurate surveillance data is needed to track the spread of disease and to make sure that fungicides are used at exactly the right time to prevent infection of wheat crops. This necessitates vast amounts of real-time data across continents in order to be effective. This sort of capacity remains out of reach for many poorer countries, although — thanks to new mobile technologies — the landscape is beginning to change.

In addition, low- and middle-income countries often lack access to registered fungicides. For example, a number of countries were hit by an outbreak of yellow rust between 2010 and 2013. In Syria, there were no registered fungicides for wheat rusts, and the country suffered production losses of over 1 million tons of wheat in 2010 alone. In Ethiopia, only non-registered, ineffective chemicals were available — so those farmers who purchased them gained nothing in terms of disease control. Even in higher income countries, it is extremely difficult to control wheat diseases solely with fungicides, and diseases, like insects, evolve resistance to sprays. The rapid spread of wheat rust makes it particularly difficult for timely spraying. By the time farmers see the disease, it can be too late

Disease-resistant varieties underpin an effective global response

UK aid funds have been supporting the vital work of international plant breeders and pathologists over recent decades to help farmers stay ahead of globally evolving wheat diseases by focusing on the genetics of wheat, rather than the production of ever more potent chemical fungicides.

Scientists in the UK and on the ground in Africa and Asia, working together through international collaborations like the Borlaug Global Rust Initiative, are producing a stream of new varieties of wheat. These new varieties are resistant to diseases, and have other desirable characteristics such as higher yields and adaptability and heat and drought tolerance.

The CGIAR’s wheat breeding programme at CIMMYT is another example of an initiative supported by UK aid. CIMMYT houses a vast genebank of 150,000 wheat seed samples from all over the world. The CGIAR, and other DFID partners, breed new varieties of wheat using combinations of older and newer varieties housed in the genebank. A variety of wheat from decades ago may suddenly hold the key to resistance in the face of emerging disease threats. This is why safeguarding and protecting these seed samples is so critical.

Varieties of resistant wheat introduced between 2009–2016 to stop the spread of Ug99 stem rust

More than 80 wheat varieties with improved rust resistance and better agronomic traits have been released and adopted in 11 ‘at risk’ countries in the last 10 years. These varieties helped reduce the threat of the dreaded Ug99 and allowed farmers to improve food security and livelihoods. In Ethiopia — a real hotspot for wheat rust disease — new disease resistant varieties have been adopted at scale, bringing an estimated US $40 million in benefits to farmers in just one crop year.

DFID has also invested in strengthening disease surveillance and epidemiology. The Rust Tracker is one example: this is now a global database of wheat rust disease sightings and data, providing scientists and policy-makers with accurate information on the spread of rust diseases. Resistant wheat varieties can then be distributed to the right places at the right times, to counter disease epidemics, to help poor farmers increase their crop yields, and to protect the food security of the 1.2 billion people reliant on wheat.

The UK contribution… and the benefits for the UK

Research collaborations are at the heart of this global effort — with a global network of wheat breeders, epidemiologists, molecular geneticists, pathologists and policy makers in developing countries, all working together to monitor and respond to wheat diseases. Innovative, cutting edge UK science has also played a critical role. Institutions like the John Innes Centre support the underpinning science, while the University of Cambridge and the UK Met Office play a key role in early warning systems. In the private sector, Oxford-based Nanopore are providing mini-gene sequencers to enable mobile real-time diagnostics. This is revolutionising the speed at which scientists can detect new diseases, from up to a year to just 2–3 days.

The investment of UK aid in wheat research is delivering real impact to poor farmers on the ground, protecting the food security of the extreme poor, and guarding against price spikes for food globally. The benefits of this global research effort can also be felt here at home in the UK, where wheat is an important crop for our own farming sector, and ubiquitous in the British diet. With our typically rainy climate, British wheat is already particularly at risk from diseases like septoria. Compounding this, globalisation and climate change are now driving greater cross-border spreads of disease. This short video features British scientists involved in global wheat research, describing how UK aid investment in wheat research delivers real benefits, not just for developing countries, but for the UK, too.

Delivering Genetic Gain in Wheat: Protecting Food Security in the UK and Abroad, published by
Borlaug Global Rust Initiative

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Research, science and technology news funded by the UK Foreign, Commonwealth and Development Office #UKAid (Before 2nd Sept 2020 blogs published by DFID).

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