This post was commissioned as part of a Pulitzer Center/Global Voices Online series on Food Insecurity  that draw on multimedia reporting featured on the Pulitzer Gateway to Food Insecurity  and bloggers discussing the issue worldwide. Share your own story here .
The risk posed by a fungus that is deadly to the world's second largest crop, wheat, continues to rise. The killer fungus, called Ug99, causes stem rust disease, which can destroy entire wheat fields.
Two new aggressive forms of the fungus were found  in South Africa for the first time earlier this year, raising concerns that it could spread. More than a billion people  in developing countries rely on wheat for their food and income.
As journalist Sharon Schmickle explored in a 2008 project for the Pulitzer Center, Ug99 poses a major threat  because 80 percent of Asian and African wheat varieties are susceptible to the fungus. Since the fungus was discovered in Uganda in 1999 it has traveled to the fields of Kenya, Ethiopia, Yemen and Iran.
At the 8th International Wheat Conference  in June, several scientific papers about risks and possible solutions to Ug99 were presented, and the discovery of the new forms of the fungus in South Africa, as well as in Kenya, were announced. In a blog post on Philanthropy Action Tim Ogden urges global poverty philanthropists to look towards agriculture and funding for science as he elaborates  on the potential consequences of this discovery:
“The new rust has become even more virulent since it emerged. Now that it’s in South Africa, the rust can much more easily spread to the Middle East and South Asia as it can hitch a ride on prevailing wind currents. As the rust spreads—killing up to 80 percent of a wheat crop—farmers around the world will have to replace the varieties of wheat that they use.”
Stem rust itself is nothing new. Controlling it was a major part of the Green Revolution  of the 1960s, when scientists introduced genes into wheat to make it resistant to the fungus. When Ug99 emerged in Uganda, it transformed stem rust from a disease largely under control to a major global threat.
A post by Allen Dodson on the Biosecurity Blog of the Federation of American Scientists insists  it's vital to deal with this threat:
Though authorities are increasingly aware of the danger [of agricultural pathogens] – whether from naturally occurring outbreaks or intentional acts of terrorism and aggression – the rapid transport of food across agricultural regions and on to markets poses a major challenge for the detection and quarantine of crop pathogens. As global populations and food requirements continue to increase, addressing the threat to the food supply will only become even more important.”
Ug99's spores are transported by wind but can also be carried on clothes or in plant matter. As it migrates it can also mutate, sometimes into deadlier forms. In addition to the new forms of Ug99 found in South Africa, researchers at the June conference also announced two new forms in Kenya. These four mutations of Ug99 have acquired the ability to defeat two of the most important stem rust-resistant genes.
On environmental politics blog Red Green and Blue, Kay Sexton says  the situation reveals how fragile our food supply is.
Monkey's Uncle blogger and biological anthropologist, James Holland Jones, says  it highlights the importance of evolutionary biology.
Commenting on an article on Wired, a reader going by the name “mwilk” thinks  the stem rust problem highlights the need for greater biodiversity:
Sounds like an updated version of the Irish Potato Famine. Another good reason why it is good practice to maintain genetic diversity in important agricultural crops and not to be too dependent on a single crop. Easier said than done in many poor countries, but in the US we certainly have the resources to maintain an agricultural base that can withstand the attack of this type of pathogen. If we have the wisdom is another matter.
Fungicides can be used to combat Ug99, but small-scale farmers without access to these chemicals remain vulnerable. So researchers are trying to stay one step ahead. In June, the Food and Agriculture Organization of the United Nations launched  the Web site Rust SPORE  to monitor the spread of Ug99 and other wheat rusts. Researchers are also working on breeding new varieties of wheat that are resistant to Ug99.
Nonetheless, Robert Winter, blogging on Idle Thoughts of an Idle Fellow, says  that both the April Deepwater Horizon oil spill  in the Gulf of Mexico and stem rust have shown the limits of technology:
Perhaps illogically, this attitude to technology and human certainty is lodged in my mind with the recent and growing concern about the spread of the ug99 wheat fungus, a stem rust that we thought we'd dealt to with our science, but has evolved into a virulent new form in Africa and has become a very serious global threat, in part as an effect of our standardisation of wheat types. I'm not a Luddite, and am in general comfortable with many aspects of technological progress, but both these cases show the inadequacy of the risk assessments that we use when we tamper with fundamental forces. It is good to understand the margins of our knowledge.
Still, Steve Savage, blogging on Sustainablog, remains optimistic, listing  four reasons why scientists will defeat stem rust:
I’ll wager that the worst potential from this disease will NOT actually occur. This is not a casual wager – the health or even survival of millions of poor people around the world is at stake. Some of my wheat breeder friends might not like me to say this (because they legitimately need more funding), but my bet is still that the breeders will prevail against all odds (and get little credit for it). I base that qualified optimism on having seen what a remarkable group of scientists called “plant breeders” have been able to achieve in the past… Will plant breeders still do their very best to protect the food supply? Yes, they will.