Coffee Disease Watch: Leaf Rust, Borers, and Rising Pest Pressure Cloud Global Production Outlook

CoffeeNetwork (New York) - Plant disease and pest pressure is once again emerging as a meaningful risk factor for global coffee supply, reinforcing longer‑term concerns around climate volatility, aging coffee trees, and uneven farm investment. While no single outbreak on the scale of the 2012–2015 Central American rust crisis is currently underway, coffee leaf rust (CLR), coffee berry borer, and localized disease complexes are exerting measurable pressure across Central America, South America, Africa, and parts of Asia, with implications for yields, costs, and quality.

Coffee Leaf Rust: Persistent Pressure Rather Than a Sudden Shock

Coffee leaf rust (Hemileia vastatrix) remains the most structurally damaging disease in global coffee production. Rather than appearing as a dramatic regional collapse, current outbreaks are persistent, weather‑driven, and highly localized, making them harder to quantify but no less relevant.

Central America: Rust Incidence Rising with Weather Volatility

The most recent USDA Coffee Annual for Guatemala (April 2026) confirms that rust pressure increased materially during early 2026, with incidence rates reaching up to 20% in some regions between January and March, following periods of above‑average humidity and elevated temperatures.

While Guatemala avoided a collapse in national output—thanks to extensive renovation programs—yield per hectare slipped, and production declined modestly year‑on‑year. Roughly 30% of Arabica plantings now consist of rust‑tolerant hybrids, limiting systemic risk but not eliminating productivity drag in older, non‑renovated plots.

In Honduras, coffee leaf rust (Hemileia vastatrix) remains a key phytosanitary concern. As of March 2026, national average incidence increased from 7.57 percent to 8.44 percent, indicating a moderate rise (Level 4, yellow alert). This increase reflects higher lesion counts and greater leaf damage, supported by favorable environmental conditions during the December–March period and the unrestricted movement of harvest workers, which can facilitate the spread of the fungus. Elevated incidence levels are reported in key producing departments, including Comayagua Department Honduras (14.08 percent), Cortés Department Honduras (12.49 percent), Santa Bárbara Department Honduras (11.17 percent), Yoro Department Honduras (10.08 percent), El Paraíso Department Honduras (9.81 percent), Intibucá Department Honduras (9.27 percent), La Paz Department Honduras (6.77 percent), Copán Department Honduras (6.76 percent), and Francisco Morazán Department Honduras (6.01 percent).

As of March 2026, approximately 5 percent of the current crop remains unharvested, while 44 percent is still in the supply chain awaiting export, roasting, or processing. Earlier survey data from Honduran Coffee Institute (IHCAFE) in April 2025 indicated that 16.67 percent of sampled farms had medium rust incidence (5–10 percent), 7.80 percent had high incidence (10–15 percent), and 21.63 percent recorded very high incidence (above 15 percent). Despite these localized pressures, overall national rust levels remain relatively contained, supported in part by dry season conditions across major producing regions. Honduran coffee is primarily cultivated at high altitudes, with 61 percent of farms located between 3,900 and 5,200 feet above sea level, and production spans 15 of the country’s 18 departments and 210 of its 298 municipalities.

Similar dynamics are being observed across El Salvador and Nicaragua, where national coffee institutes report higher treatment costs and rising fungicide applications amid more erratic rainfall patterns. The disease remains endemic rather than epidemic, but climate‑linked moisture cycles are increasing baseline pressure across the region.

South America: Rust Contained, But Not Absent

In Brazil and Colombia, rust remains largely under control due to varietal replacement and widespread fungicide use, though agronomic reports indicate sporadic flare‑ups in lower‑altitude Arabica and Conilon areas during wetter‑than‑normal periods. The risk is not immediate crop loss, but gradual yield attrition and higher cost structures, particularly for smaller producers.

Coffee Berry Borer: The Silent Yield Thief Expands

If leaf rust is the most visible disease risk, coffee berry borer (CBB – Hypothenemus hampei) is the most economically destructive pest worldwide, causing annual losses estimated above US$500 million globally.

In September 2025, ANACAFE in Guatemala reported the identification of the coffee borer Xylosandrus compactus (Eichhoff) in Zacapa, Retalhuleu, Quetzaltenango, and San Marcos at altitudes of 600 to 900 meters. This pest was first reported in 2024 in avocado and cedar but subsequently appeared scattered in some Robusta trees. Although ANACAFE has provided control measures, including natural and chemical controls, manual control appears to be the most effective method to prevent spreading.

Brazil continues to face rising CBB pressure, particularly in warmer zones of Minas Gerais, Espírito Santo, and Bahia. Industry and research reporting confirms that warmer temperatures are accelerating beetle reproduction cycles, increasing infestation intensity and shortening control windows.

Biological control solutions, including Beauveria bassiana‑based products, are gaining traction as chemical options tighten, but efficacy depends heavily on timing, labor availability, and weather conditions.

CBB remains widespread throughout Central America, East Africa, and increasingly parts of Uganda, Tanzania, and Kenya, where warming highland zones are becoming more hospitable to the pest. Research bodies note that altitude is no longer the reliable safeguard it once was, as beetles expand upward into traditionally cooler regions.

Coffee Berry Disease and Other Fungal Threats in Africa

Beyond leaf rust and borer pressure, Coffee Berry Disease (CBD – Colletotrichum kahawae) remains a major yield risk in Africa, particularly in Ethiopia, Uganda, Rwanda, and Kenya. Scientific reviews published in 2025 highlight increasing concern over co‑infection scenarios, where rust, CBD, and pest pressure overlap, compounding damage and accelerating tree exhaustion.

Rwanda’s recent export surge has masked these risks for now, but NAEB and regional agronomists continue to flag disease pressure as a medium‑term constraint to sustained growth, particularly for smallholders reliant on limited fungicide access.

In Vietnam and Indonesia, leaf rust and leaf miner remain present but manageable. However, higher humidity variability linked to El Niño cycles has increased disease monitoring efforts, particularly for Robusta systems that historically faced lower disease incidence than Arabica counterparts.

Elsewhere, Hawaii, once considered rust‑free, continues to manage CLR after its initial detection, underscoring how biosecurity assumptions are shifting globally.

From a supply‑side perspective, current disease and pest pressures are unlikely to trigger an immediate global production shock. However, they reinforce three longer‑term realities for the coffee market: Rising cost of production, as fungicide, biological controls, and labor requirements increase; Lower yield ceilings, even in well‑managed systems; and increased divergence between renovated and non‑renovated origins, widening quality and availability spreads.

In short, pests and diseases are no longer one‑off crises—they are structural headwinds shaping the coffee supply curve.

Alexis Rubinstein