Dothiora hemp blight

Dothiora hemp blight is a fungal disease caused by the ascomycete Dothiora cannabinae. This pathogen specifically targets hemp plants, colonizing the stems and compromising the structural integrity of the plant tissue essential for fiber production.

The disease is characterized as a stem blight, where the fungus penetrates the epidermis and cortex. By colonizing the intercellular spaces, the pathogen causes necrosis of the outer tissues. The life cycle involves the production of spores that are easily disseminated by wind and water splash, leading to secondary infections within the field.

The primary symptoms manifest as dark, sunken lesions on the hemp stalks. As the infection progresses, the epidermis may crack or peel, revealing necrotic tissue. The presence of small, dark fruiting bodies of the fungus on the affected stem surface is a key diagnostic feature used to identify the pathogen in the field.

Favorable conditions for the development of Dothiora cannabinae include high humidity and moderate temperatures. Dense plant stands, which restrict airflow and maintain a humid microclimate around the stems, are particularly susceptible to severe outbreaks. Mechanical injuries caused by pests or equipment can also facilitate the entry of the fungus.

The economic impact of this disease is significant due to the reduction in fiber quality and yield. Infected stalks become brittle, leading to poor fiber extraction and diminished industrial value. Controlling this pathogen is essential for maintaining consistent fiber quality in commercial hemp production.

• Implementing crop rotation to minimize the build-up of fungal inoculum in the soil.
• Removing and destroying crop residues after harvest to reduce overwintering sites.
• Maintaining optimal plant spacing to promote effective air circulation.
• Using certified disease-free seeds and performing seed treatments where applicable.
• Applying fungicides during the early stages of disease development to curb spread.