Yeast spot

Yeast spot, caused by the fungus Eremothecium gossypii, is a significant plant disease that primarily affects leguminous crops, such as common beans, and cotton. As an ascomycete fungus, it acts as an intracellular parasite, causing localized necrotic damage to the plant tissue and affecting the overall vigor and yield potential of the crop.

The disease is particularly notorious for damaging common beans. When the pathogen infects the developing pods, it directly affects the seeds inside, leading to spotting, discoloration, and reduced seed viability. This makes yeast spot a critical concern for farmers aiming to produce high-quality seeds and marketable pods.

Typical symptoms include the appearance of yellow to dark brown necrotic lesions on leaves, stems, and pods. These spots are the result of the fungal colonization of the plant tissue. In advanced stages, the lesions can cause the pods to shrivel, and in wet conditions, a slight fungal growth might be visible on the surface of the infected areas.

The transmission of Eremothecium gossypii is heavily dependent on insect vectors, most notably plant bugs (Hemiptera). When these insects feed on the plant by piercing the tissues, they introduce the fungal spores directly into the healthy plant parts. Consequently, the prevalence of these insects during the plant's flowering and pod-filling stages is the primary driver of disease outbreaks.

Effective management requires an integrated approach to protect crops. Key strategies include:

• active monitoring and control of insect vectors using appropriate insecticides;
• planting certified, disease-free seed stocks;
• sanitizing fields by removing crop residues that may harbor the fungus;
• rotating crops with non-host species;
• application of protective fungicides when environmental conditions favor disease spread.