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What is Coffee Rust? Causes & How It Affects Coffee

person showing coffee rust

Growing and farming plants is a lot of work, especially in elevated places like mountains or areas with unpredictable weather. A lot of things can happen to cause plants to wither or die. Insects, poor sunlight, not enough water, too much water, poor nutrition, and too much sunlight are all things that can create serious problems with crops, which can result in a smaller harvest and a loss in income.

Another problem is plant diseases and fungi, which can devastate a large percentage of crops. Coffee plants are prone to various infectious conditions, which can cause serious financial destruction to farmers in poorer areas. One disease that coffee plants tend to get is “coffee rust”, a damaging fungal infection that will kill coffee plants if not caught early enough. Not only is it devastating to one plant, but it can also take out an entire plot of coffee plants.

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What is Coffee Rust?

Coffee rust is a type of fungus that causes yellow-brown spotting and leads to a reddish-orange dust-like texture. Called Hemileia Vastatrix in the scientific world, coffee rust slowly but devastatingly rots out the coffee plant leaves and causes the leaves to break off or fall on their own, severely lowering the quality and quantity of the coffee fruits. It can also kill the plant with ease if left untreated.

The unyielding fungus has caused serious coffee farm epidemics, with the worst devastation in poor areas that have little to no funds to fight it off. Even in areas that can afford to treat it, coffee rust often grows immune to the latest fungicides. Even larger coffee-producing countries like Brazil, Colombia, and Honduras have fallen prey to the unforgiving fungi, causing drops in the total amount of exported coffee beans.

What Causes Coffee Rust?

Coffee leaf rust is a fungus that spreads mostly by wind, but it can also spread from the clothing of farmers or even animals that are unknown hosts of the spores. The fungal spores, once they come in contact with a coffee plant, attach themselves and begin their growth cycle, eventually spreading to other plants. It creates serious problems for the plants by depriving them of their ability to photosynthesize, as well as thriving in the very conditions that coffee plants also thrive in.

If coffee rust infects one plant and isn’t caught soon enough, it can spread within 24-48 hours and cause a mass infection. For coffee farmers who haphazardly plant their crops at elevation, their lack of planning may help because the plots are not in contact with one another. However, for coffee farmers with a more organized approach, their entire plot may catch this destructive fungus.

Coffee rust on leaves
Image Credit: Viola Hofmann, Shutterstock

Is Coffee Rust Treatable?

While coffee rust is somewhat treatable with fungicides, most problems come down to money and the fungi’s growing resistance to treatment. Scientists aren’t exactly sure how coffee rust grows immune to treatments, which means there’s no way to prevent it completely. One way to treat it is with fungicides, but coffee farmers in third-world countries can’t afford to keep treating the plants over and over again.

Another way to treat coffee plants with coffee rust is to quarantine the infected plants. But, that can be nearly impossible if there are hundreds of plants that may have come in contact with the fungus and showing no symptoms. It’s why the fungus is so deadly and costly to farmers, leading to low-quality coffee and smaller harvests. As of right now, there is no known cure for coffee rust and it will continue to wreak havoc until there’s a true cure.

Is Coffee Rust Preventable?

Preventing coffee rust is, of course, the only way to treat it without spending thousands on chemical treatments, but it’s also almost impossible to do. But, because coffee rust is a fungus that spreads mostly by wind and comes in contact with a coffee plant, finding the original host is next to impossible.

If caught early enough, quarantining the host plant or the first plant to be infected plus the surrounding plants around the infected one is the best possible way to prevent a huge loss. However, spotting signs of coffee rust before it spreads to other plants is very difficult because of how quickly it grows.

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Other Diseases Coffee Plants are Prone to:

While coffee leaf rust is probably the worst possible coffee plant disease that can hit a coffee plantation, there are other significant diseases and conditions that they’re also prone to:

  • Root Rot – A common problem among many plants, root rot is either caused by overwatering or by an underlying condition that leads to it. When coffee plants start to yellow or wilt, root rot could be the cause of the problem.
  • Pests – Pests are a serious problem for farmers of all crops, but many people don’t realize that they also attack coffee plants. Plant-eating pests that use the coffee plant as a host to lay eggs can destroy coffee plants easily if not spotted right away.
  • Coffee Fruit Disease – Another serious coffee plant fungal disease, Coffee Fruit Disease infects and kills the coffee cherries on Arabica coffee plants. Arabica beans are the most popular type of coffee bean, so coffee farmers do everything they can to treat and prevent it.
  • Coffee Wilt Disease – A vascular problem that attacks the plants from within, Coffee Wilt Disease is extremely deadly to coffee plants and sucks them completely dry until they wilt. It’s also yet another fungal-caused disease that can ravage any coffee farm, also spread by wind.

Featured Image Credit: Noiz Stocker, Shutterstock


Jaimie Wisniowski

Jaimie is a freelance writer fueled by coffee, whether it’s hot, iced, or made from a local coffee shop. She enjoys writing all things coffee, especially if it means trying the latest coffee shop trends (hello cold foam!). After spending years writing poems, college essays, and short stories, it only a matter of time to turn writing into a career. Writing about coffee simply combined two of her favorite things! When she’s not drinking coffee by the minute and writing at her laptop, Jaimie spends time hiking, exercising, and living an active life. She also loves to snuggle up with a good book and her dog, Margo. If you catch her without a cup of coffee, she’s probably on her way to the coffee maker now.

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