Anthracnose in Coffee Plants: Symptoms and Control

Anthracnose is one of the most damaging fungal diseases affecting coffee plantations across tropical and subtropical growing regions. Caused primarily by Colletotrichum gloeosporioides, it attacks multiple parts of the coffee plant simultaneously – leaves, berries, and twigs – leading to measurable yield and quality losses if left unmanaged. Understanding what this disease looks like, what conditions drive it, and how to control it is essential knowledge for any serious coffee grower.

What is anthracnose in coffee? 🔗

Colletotrichum gloeosporioides is a cosmopolitan fungal pathogen that infects a wide range of crops, including mango, papaya, avocado, and coffee. In coffee specifically, the fungus can behave as a latent pathogen – remaining inactive in plant tissue for a period before symptoms become visible. Once conditions turn favorable, it shifts from dormant to destructive, breaking down host cell walls using enzymes and spreading rapidly through the plantation. The disease is also sometimes referred to as brown blight when describing the characteristic leaf damage it causes on coffee and tea plants.

Symptoms of anthracnose on coffee plants 🔗

Anthracnose presents in three distinct ways on coffee, each affecting a different part of the plant. Recognizing all three is key to catching infections early.

Twig die-back 🔗

One of the earliest and most visible signs is die-back of twigs and young branches. The deterioration typically starts at the tip of the twig and progresses downward, causing progressive wilting and death of the affected shoot. As the disease advances, sunken cankers can form on twigs and branches, weakening the plant’s overall structure. Heavily infected plants display a characteristic pattern of dead, leafless stems scattered throughout the canopy.

Stalk rot of berries 🔗

The fungus also attacks the berries through their stalks, causing stalk rot. Infected berries become shriveled and discolored, and many drop from the plant prematurely before they can be harvested. In Puerto Rico, C. gloeosporioides has been confirmed to infect coffee fruit across multiple organs, and fungicide and fertilization inputs were found to meaningfully reduce this berry rot. Beyond the direct yield loss, pre-harvest fruit drop reduces the overall quality of the crop and increases post-harvest disease risk from secondary infections.

Brown blight of leaves 🔗

On the foliage, anthracnose produces brown, necrotic spots that expand over time and eventually merge into larger blighted areas. Infected leaves develop irregular dark areas, and in severe cases the entire leaf surface becomes affected, leading to defoliation. Leaf drop directly reduces the plant’s capacity to photosynthesize, which in turn weakens its ability to support berry development. Early symptoms on leaves can also include yellowing and premature mid-branch leaf drop before the characteristic brown spots fully appear.

Conditions that favor anthracnose development 🔗

Knowing when and why anthracnose flares up is just as important as identifying its symptoms. The disease does not develop randomly – specific environmental and agronomic conditions consistently set the stage for outbreaks.

Warm, humid weather 🔗

The fungus thrives when temperatures sit between 22°C and 32°C combined with relative humidity above 90%. These conditions are most commonly found in the wet seasons of tropical coffee-growing regions. According to the Hawaii Coffee Education program, temperatures of 75°F (approximately 24°C) and above accelerate anthracnose development noticeably, while cooler conditions below 59°F slow its progression.

Prolonged wet periods and rain splash 🔗

Extended rainfall is a major driver of disease spread. The Colletotrichum fungus produces spores (conidia) that are dispersed primarily by rain splash and air transmission. Once splashed from infected plant material or crop residues onto healthy tissue, spores germinate and initiate new infections. This is why incidence often spikes sharply at the onset of the rainy season.

Poor air circulation and dense canopy 🔗

Plantations where coffee trees are densely planted or left unpruned create a humid microclimate within the canopy – ideal conditions for fungal growth. Poor air movement within the canopy extends the time that leaf surfaces remain wet after rain or dew, giving spores more opportunity to germinate and penetrate host tissue.

Nutritional stress 🔗

Plants that are poorly nourished are significantly more susceptible to anthracnose. The FAO’s Arabica Coffee Manual specifically identifies low leaf nitrogen and potassium, combined with insufficient shade and poor fertilizer management, as key predisposing factors for anthracnose and related diseases. A stressed, nutrient-deficient plant simply lacks the physiological resources to mount an effective defense against fungal attack.

Management and control strategies 🔗

Effective anthracnose management in coffee is not based on any single measure. A combination of cultural practices, nutritional management, and targeted chemical use gives the best results.

Maintaining adequate shade 🔗

Shade management is a foundational cultural tool. The FAO recommends maintaining approximately 50% shade cover for well-fertilized coffee plants to reduce disease pressure. Shade trees moderate temperature and humidity at the canopy level, reducing the microclimatic extremes that favor fungal development. They also provide a physical barrier that reduces the intensity of rain splash – one of the primary mechanisms by which Colletotrichum spores spread between plants. However, shade management requires balance: excessively dense shade can itself create stagnant, humid conditions that may worsen fungal disease.

Balanced nutrition 🔗

Ensuring adequate and balanced crop nutrition is one of the most cost-effective disease management inputs. Plants supplied with sufficient nitrogen, potassium, and micronutrients maintain stronger tissue integrity and more active defense mechanisms. Regular soil and leaf tissue testing helps identify deficiencies before they weaken the plant. Fungicide and fertilization programs used together have been shown to reduce anthracnose on coffee fruit more effectively than either input alone.

Pruning and sanitation 🔗

Removing infected twigs, branches, and fallen berries reduces the amount of fungal inoculum available in the plantation. Dead and diseased material should be collected and destroyed rather than left on the ground, where the fungus can survive in crop residues and continue to sporulate. Pruning also opens up the canopy, improving air movement and reducing the humidity levels that favor infection. The UC IPM program recommends pruning during the dry season to remove the previous season’s diseased material before the next infection cycle begins.

Fungicide applications 🔗

Fungicides are most effective when applied preventively – before disease pressure peaks – rather than as a reactive cure. Copper-based fungicides such as copper hydroxide and copper oxychloride are widely used because of their broad-spectrum activity and relatively low cost. Systemic fungicides such as azoxystrobin and difenoconazole offer deeper protection by moving within plant tissue, providing more comprehensive coverage. The Hawaii Coffee Education program advises rotating fungicides across different chemical classes to reduce the risk of resistance developing over time. Timing applications to coincide with the onset of wet conditions – when infection risk is highest – maximizes their effectiveness.

Integrated pest management (IPM) 🔗

An IPM approach combines all of the above strategies into a coordinated, season-long management program. This means regular plantation monitoring to detect early symptoms, scheduled pruning and sanitation, nutrition management based on soil and tissue data, and fungicide applications timed to infection risk windows rather than applied on a blanket calendar schedule. Research has identified biological control options as well, including antagonistic microorganisms that can inhibit or out-compete Colletotrichum gloeosporioides – a promising sustainable complement to chemical control, particularly for growers operating under organic or low-input production systems.

Early detection is key 🔗

The single biggest factor determining the severity of an anthracnose outbreak is how quickly it is detected. By the time extensive die-back, heavy berry drop, and widespread leaf blight are visible across a plantation, significant damage has already occurred. Growers should scout plants regularly during and after wet weather, paying close attention to twig tips, developing berries, and mid-canopy leaves where early yellowing and small lesions often appear first. Acting at the first sign of infection – removing infected material, adjusting nutrition, and applying fungicide if warranted – limits spread and protects yield.

What do you think? Given that anthracnose thrives under humid, nutrient-stressed conditions, how would you prioritize shade management versus nutritional inputs as your first line of defense in a coffee plantation? And with fungicide resistance becoming an increasing concern, do you think biological control options could realistically replace chemical fungicides for small-scale coffee growers?

References

1. https://wiki.bugwood.org/Colletotrichum_gloeosporioides
2. https://bioprotectionportal.com/resources/anthracnose-how-to-identify-prevent-treat-the-harmful-fungi/
3. https://ipm.ucanr.edu/home-and-landscape/anthracnose/
4. https://apsjournals.apsnet.org/doi/10.1094/PHYTO-02-20-0057-R
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC10302910/
6. https://www.hawaiicoffeeed.com/anthracnose.html
7. https://www.fao.org/4/ae939e/ae939e0b.htm