Coffee blister

Coffee blister, widely known in agronomy as Cercospora leaf spot, is a fungal disease caused by the pathogen Cercospora coffeicola. It is a major constraint in coffee production worldwide, significantly affecting both plant health and the final yield. The disease is characterized by its ability to spread rapidly in favorable environmental conditions, causing substantial economic losses.

The disease primarily affects various species of coffee plants, most notably Coffea arabica and Coffea canephora. The pathogen targets the foliage, where it inhibits the plant's ability to photosynthesize effectively, and the coffee berries, which can lead to poor grain quality and damage to the parchment, ultimately reducing the market value of the harvest.

The primary symptoms appear as small, circular, brown to reddish-brown spots on the leaves. As the infection progresses, these spots develop into raised, blister-like lesions with a light-colored or gray center surrounded by a dark brown halo. Heavy infestations lead to chlorosis, severe leaf drop, and dieback of the twigs.

Environmental conditions such as high humidity, frequent rainfall, and moderate temperatures are critical for the development and spread of this disease. Spores are disseminated primarily through splash dispersal (rain) and wind movement. Plants that are already stressed due to poor soil fertility or inadequate canopy management are significantly more susceptible to infection.

Integrated management is essential for controlling coffee blister and maintaining healthy plantations:

• Regular pruning to improve air circulation and sunlight penetration within the canopy.
• Sanitation practices, including the removal and destruction of infected leaves and berries.
• Application of copper-based fungicides during the peak risk periods.
• Balanced nutrient management to ensure trees remain vigorous and resistant to stress.
• Proper spacing between trees to prevent the creation of highly humid microclimates.