Coffee leaf rust is a fungus that attacks the underside of leaves. It leaves orange powder, then drops the leaves. A tree without leaves cannot feed its cherries.
The disease has hit farms since the 1800s. It ended coffee growing in Sri Lanka, which switched to tea. Outbreaks in Central America in the early 2010s cost farmers billions and many jobs.
Why it comes back
Rust thrives in warm, humid air. Climate change expands the range where it can live. Farms at higher altitude, once safe, now report cases.
Spores also travel on wind, rain and workers’ clothes. One infected plot can seed a whole valley.
The breeding answer
Breeders cross arabica with varieties that resist rust. Several resistant lines now exist. Farmers have planted them across Latin America and Africa.
The challenge is flavour. Early resistant lines tasted flat. Newer crosses score much higher in cupping. Some now match classic varieties.
The cost to the farmer
Replanting takes years. A new tree gives its first real crop after about three years. A farmer must pay for seedlings and wait.
Resistance is only useful if the farmer can afford to plant it.
Funds and nurseries can bridge the gap. Some roasters now pay upfront for replanting. That support matters as much as the science.
What to watch
Watch the new hybrids at coming competitions. If they win, buyers will ask for them. Demand will pull the planting forward.
