Botryosphaeria stem canker

Botryosphaeria stem canker is a serious fungal disease caused by the pathogen Botryosphaeria corticis. This fungus primarily attacks the stems and branches of host plants, causing the formation of cankers that inhibit the transport of water and nutrients. If left unmanaged, the infection can lead to the widespread dieback of branches, significantly reducing the overall yield and vitality of the plantation.

Cranberries are the primary host for this pathogen. The disease affects the woody tissues of the plant, often entering through natural openings or mechanical wounds caused by harvesting equipment, insects, or environmental stress such as frost damage. Once the fungus establishes itself in the stem, it progresses internally, eventually girdling the branch and causing the distal portion to wither and die.

Symptoms typically begin as small, reddish to brownish lesions on the stems. As the infection progresses, these lesions enlarge into elongated, sunken, and cracked cankers. In severe cases, the bark may peel away, revealing the damaged wood underneath. Affected branches often show signs of chlorosis, leaf drop, and eventually complete necrosis, which is especially noticeable during the active growing season.

The development and spread of Botryosphaeria corticis are highly dependent on environmental conditions, particularly high humidity and moderate temperatures. Spores are primarily disseminated by water splash and wind, facilitating the spread of the disease within the planting. Poorly drained sites or areas with high planting density are particularly susceptible to rapid disease progression.

Management and prevention strategies are essential for maintaining crop health:

• Regular monitoring of the plantation for early signs of stem lesions.
• Prompt removal and destruction of infected stems to reduce inoculum pressure.
• Application of preventative fungicides during periods of high risk or after pruning.
• Maintaining proper spacing and air circulation to keep foliage and stems dry.
• Managing environmental stresses to prevent mechanical injury that allows pathogen entry.