More than 600 million people could be fed each year by halting the spread of fungal diseases in the world's five most important crops -  rice, wheat, maize, potatoes and soybeans

Recent data further suggests that in 70% of cases where infectious disease causes the extinction of a type of animal or plant, an emerging species of fungus is behind the problem. 

Fungal infections presently destroy at least 125 million tons of rice, wheat, maize, potatoes and soybeans, crops which provide the majority of calories consumed by people. The damage caused by fungi to rice, wheat and maize alone costs global agriculture $60 billion per year. The effects are disproportionately catastrophic for those in the developing world, where 1.4 billion people live on less than $1.25 per day, and rely most heavily on these low-cost foods.

Diseases like rice blast, soybean rust, stem rust in wheat, corn smut in maize and late blight in potatoes affect more than just productivity; many have wide ranging socio-economic costs. Trees lost or damaged by fungi fail to absorb 230-580 megatons of atmospheric CO2, equivalent to 0.07% of global atmospheric CO2, an effect the scientists say is likely to be leading to an increase of the greenhouse effect.

The solution to all these problems is science, free of environmental scare marketing.  Specifically, being able to genetically modify crops so that they can resist fungus without harmful chemicals. But Europe will need to overcome its entrenched anti-science mentality. Until then, scientists continue to improve chemical solutions. Bayer CropScience, for example, received the first registration for its new penflufen fungicidal seed treatment product (Emesto) in the United Kingdom, for use in potato cultivation. In testing, it showed outstanding efficacy against black scurf (Rhizoctonia solani), and significantly enhanced quality and the marketable yield.  Penflufen belongs to a new generation of SDH (succinate dehydrogenase) inhibitors. Products based on SDH inhibitors have seed invigoration and root-growth-promoting effects, offering farmers excellent disease control, not only against black scurf but also against silver scab and other diseases – at low application rates. 

Emesto SDH (succinate dehydrogenase) inhibitors save potatoes.  Credit: Bayer CropScience

That's a big win for hungry people worldwide.

In animals, new fungal diseases increasingly threaten the existence of over 500 species of amphibian, as well as many endangered species of bees, sea turtles and corals. In the US alone, studies suggest the decline in bat populations caused by white nose syndrome fungus will lead to a dramatic rise in the insect crop-pests that the bats would otherwise eat, and a cost to agriculture of more than $3.7 billion per year.

Dr Matthew Fisher, from the School of Public Health at Imperial College London, and a corresponding author of a new study of fungal disease, said, "The alarming increase in plant and animal deaths caused by new types of fungal disease shows that we are rapidly heading towards a world where the 'rotters' are the winners. We need strive to prevent the emergence of new diseases as we currently lack the means to successfully treat outbreaks of infection in the wild."

Fungal diseases have been increasing in severity and scale since the middle of the 20th century, largely thanks to trade and travel, and now pose a serious danger to global food security, biodiversity and ecosystem health. The threat to plants from fungal infections has now reached a level that outstrips that posed by bacterial and viral diseases. The authors calculated that fungal infection could damage of up to 900 million tons of food if disease epidemics were to hit all the top five food crops in the same year. Although the chances of this happening are very slight, they estimate that this scenario would cause a global famine leaving over 4.2 billion people starving.

Corresponding author, Sarah Gurr, Professor of Molecular Plant Pathology at the University of Oxford, said: "Crop losses due to fungal attack challenge food security and threaten biodiversity, yet we are woefully inadequate at controlling their emergence and proliferation. We must have better funding channeled into the fight against fungal disease."

Citation: MC Fisher et al. "Emerging fungal threats to animal, plant and ecosystem health." Nature, 12 April 2012. DOI 10.1038/nature10947