Kabatina shoot blight

Kabatina shoot blight is a fungal disease caused by the pathogen Kabatina thujae, which primarily affects coniferous trees and shrubs. This fungus is a serious concern for nursery growers and gardeners, as it leads to necrosis of the shoots and significant aesthetic degradation of the plant, often causing the death of terminal branches.

The disease affects various species within the Cupressaceae family, most notably the Western Thuja and different juniper species. The pathogen typically enters the plant through wounds caused by insects, mechanical damage from pruning, or natural cracks in the bark. It spreads internally, disrupting the plant's nutrient transport system in the affected shoots.

Symptoms usually appear in early spring. Initially, the needles on the tips of the previous year's shoots turn yellow, gradually transitioning to a dull brown or grayish-brown color. A definitive diagnostic feature is the presence of small, black, cushion-like fruiting bodies (acervuli) of the fungus that erupt through the epidermis of the needles and twigs.

The development and spread of Kabatina thujae are highly favored by cool, wet weather conditions. Spores are disseminated by splashing water, rain, and wind. High plant density and poor air circulation within the canopy create a microclimate that allows the fungus to thrive and infect healthy tissue during the entire vegetative season.

Effective control requires an integrated approach. The most critical step is the timely pruning and destruction of all infected branches, ensuring that tools are disinfected after each cut to prevent cross-contamination. Preventive spraying with copper-based fungicides in the spring, combined with maintaining optimal tree vigor, significantly reduces the risk of widespread infestation.

• Prune and destroy infected plant material immediately.
• Disinfect garden tools with 70% alcohol or bleach.
• Apply copper-based fungicides to protect healthy shoots.
• Improve air circulation by thinning out dense foliage.
• Avoid overhead irrigation that keeps the foliage wet.