Royal fungus saps coffee leaves of nutrients and causes plants to yield fewer coffee beans. Also known as leaf rust, the fungus has been creating blights in Central America on coffee farms that are at lower elevations. This year, the blight has risen to higher elevations than ever seen before.

It's a big enough cause for concern that Starbucks has decided to invest in a 600-acre coffee farm in Costa Rica that will in part research leaf rust. NBC News reports the farm will also be used to grow coffee beans for Starbucks to use in its coffee houses.

How devastating is leaf rust?

The International Coffee Organization recently estimated that some 2.5 million 60-kg bags of crop could be lost in the 2012/13 global coffee output due to the disease, with losses possibly rising to around 4 million bags in 2013/14.

Based on ICO data, those forecasts would equate to between 18 percent and almost 30 percent of Central America's crop in 2011/12.

I spent a week last summer visiting several of the coffee farms in Guatemala. I saw how through the use of sustainability initiatives and smart business practices the coffee farmers in the country were just beginning to bring themselves out of long-term poverty by producing higher yields of better coffee beans that are grown sustainably. They are able to charge a higher price for their coffee because of its quality. I would think that a 30 percent loss of their crop would severely set back the progress they've made in Guatemala and other countries like Costa Rica.

I think Starbucks is doing a good thing by investing in research. Obviously, it's in the company's best interest so they can continue to buy quality beans from Central American countries. Their research will also benefit the coffee farmers who are just beginning to improve their lives and the lives of their children through the economic, environmental and educational benefits they've gained through sustainable coffee farming.

Starbucks' investment in this farm is an extension of their ethical sourcing program, so it's reasonable to assume that this coffee farm will be sustainable, too. The company defines ethical sourcing as "responsible purchasing practices, farmer loans and forest conservation programs."

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