Penicillium grain rot

The causative agent of this disease is the fungus Penicillium verrucosum, a common saprotrophic mold known for causing significant post-harvest losses. This fungus is highly specialized in colonizing stored cereal grains and oilseeds, often thriving in environments that are poorly ventilated or improperly dried.

The pathogen primarily affects cereals such as wheat, barley, rye, and oats. While it can occur in the field during wet harvesting conditions, it is most destructive in storage facilities. It targets the germ and endosperm of the seed, rapidly compromising the nutritional and biological integrity of the harvest.

Symptoms are easily identified by the appearance of a characteristic blue-green to olive-colored powdery mycelium on the surface of the kernels. The affected grain loses its natural luster, becomes discolored, and develops a distinct musty odor. As the infection progresses, the grain embryo dies, making the product unsuitable for milling or sowing.

The development of Penicillium verrucosum is strictly regulated by environmental factors, primarily moisture content and temperature. It thrives when grain moisture exceeds 15% and ambient relative humidity remains above 75%. In these conditions, the fungus rapidly forms spores, which are easily disseminated throughout the grain mass by air currents.

The most severe threat posed by this fungus is the production of mycotoxins, specifically ochratoxin A. These secondary metabolites are toxic to both humans and livestock, causing chronic health issues including nephrotoxicity. Because these toxins are heat-stable, they remain in the grain even after processing, posing a major risk to food safety.

• Strict control of moisture levels in stored grain below 14%.
• Regular cleaning and sterilization of silos and grain handling equipment.
• Ensuring adequate aeration to prevent hot spots within the grain bulk.
• Testing grain batches for mycotoxin levels during storage.
• Rapid cooling of grain immediately after harvest to inhibit fungal growth.