Roya
Coffee Leaf Rust
The coffee tree is vulnerable to a range of biological threats, but few have been more destructive than coffee leaf rust. Known in many countries as roya, this fungal disease, caused by Hemileia vastatrix, produces orange lesions on the leaves, reduces photosynthesis, weakens the plant, and can ultimately defoliate a tree so badly that it dies.
Leaf rust was first documented in East Africa in the nineteenth century, but its historical importance became unmistakable when it devastated coffee production in Sri Lanka after 1869. In the modern era it reached Brazil and spread quickly into Central America. Today it is found in every major coffee-producing region, and higher temperatures associated with climate change are making the problem more severe rather than less. When rust pressure rises, producers are not confronting a cosmetic blemish. They are protecting the engine that powers the tree's growth and fruiting.
Broca
Coffee Berry Borer
The coffee berry borer, often called broca, attacks the crop from the inside. This small beetle lays its eggs in the cherry, and the larvae feed within the fruit itself, reducing both yield and cup quality before processing has even begun.
Native to Africa but now widespread across the coffee world, the berry borer is often described as the most harmful insect pest affecting coffee today. Producers and researchers use a range of control strategies, including pesticides, traps, and biological methods, but every approach carries costs and limitations. The larger lesson is simple: a great cup depends on defending the crop long before it ever reaches a wet mill or roastery.