Prepare for a pricier latte.

Caffeine junkies got some rather troubling news recently, as growers around the world face the one-two punch of drought and disease. Outlets around the world have begun reporting anticipated shortfalls in Vietnamese coffee production. Due to a long-running drought condition, with months of below-average rainfall, the country is expected to produce well below its annual yield this season.

Approximately 343,500 acres of the winter-spring crop have been damaged, reports Agence France-Presse, with the land hurt by both the water shortage and resulting salinity from the Mekong Delta.

Vietnam is the world’s largest producer of robusta coffee beans, along with Arabica, one of the two main varieties of coffee used in global production. While Arabica is generally used in high quality mixes, such as espresso, producers rely on the heartier robusta for products such as instant and inexpensive coffee. (Popular brand Folgers, for example, uses robusta or a robusta/Arabica blends in most of its coffee.)

Swings in commodity prices have become a staple of the coffee market for years, as producers shift their blends based on relative expense. In particular, the fact that robusta and Arabica are most densely grown in different regions of the world have often helped the two varieties offset each other’s prices, insulating the market from annual shocks.

Whereas robusta is most densely grown in Southeast Asia and Africa, Central and South American growers generally focus on Arabica beans.

Yet as drought conditions settle in on the world’s foremost producer of robusta, Central American and Mexican farmers are struggling themselves. For the past four years they’ve seen the rise of a deadly fungus known simply as coffee rust.

According to University of Michigan professor Ivette Perfecto, it has been devastating.

“It has been a huge problem in Central America and the Caribbean, and northern South America,” she said. “This would be the equivalent of a drought in Vietnam.”

Noted by its namesake red discoloration of the plant leaves, coffee rust isn’t a new disease but it is recently arrived as a plague to the Western Hemisphere. Its effects can lay waste to production. Over 200 years ago, when it struck Southeast Asian growers, it wiped out coffee production almost wholesale over entire regions.

“That’s why you have mostly tea production in that region,” Perfecto said.

“When it was first introduced [in the Americas] people were freaking out," he added. "People thought this was going to be the end of coffee production in the Americas.”

And despite first reappearing over 30 years ago, the devastation didn’t happen. For decades rust remained a nuisance, sometimes more, but never a regional threat. All that changed around 2012, when massive outbreaks of rust began to spread virulently across fields, particularly in Mexico. Now the blight is so common that many farmers say their yields are down to 60%, and others have given up altogether.

No one knows what caused the outbreak.

Perfecto theorizes that it has been caused by the specific combination of factors that farmers use to mass produce the Arabica beans. Fungicides, lack of biodiversity, even clear cutting all help to eliminate biological competition and ensure the widespread travel of the rust’s airborne spores.

The result, as many shoppers have noticed, has been a steady climb in the price of high quality Arabica beans over the past several years.

This uncertainty, and the confluence of multiple simultaneous factors, also makes the rust notoriously difficult to deal with. Without an effective fungicide to combat the rust, farmers instead will likely have to rely on changing environmental conditions to make their fields more hostile to it (if researchers can figure for certain what is causing the spread). The trouble, however, is that it will take a long time and lot of effort before those results can see fruit.

“As the problem of the coffee rust gets people to abandon coffee [growing],” she said, “or to plant new, more resistant varieties, you’re going to start seeing a decline.”

Now that the rust has spread, Perfecto explained, pushing it back will require conditions significantly more hostile to the invasive fungus than they were before. Simply going back to the growing conditions farmers used prior to the outbreaks won’t be enough.

In other words, getting rid of this blight will be a long, slow process, once farmers and researchers can even be certain how it spreads in the first place.

For farmers who focus on growing robusta beans, again primarily in Asia and Africa, coffee rust is less of a problem. The robusta variety is considerably heartier in several respects, including resistance to disease.

Which is why news of this drought, for anyone concerned about the price at the pot, is particularly grim. Vietnam’s weather conditions will hit the largest grower of robusta beans at the same time as a deadly fungus continues its march through the fields of Mexico and Central America. Two of the largest coffee growers in the world will see their production decline, one rapidly and the other as part of a years-old problem.

The result will wipe out small farms around the world, the kind that operate on annual margins and can’t afford to lose half their crop in a single year. It will also shake the commodities market worldwide.

The price of coffee is about to go up… and it’s only the tip of the iceberg.