Cylindrocladium blight

The disease caused by Cylindrocladium clavatum is a significant fungal infection affecting various nursery and forest plant species. The pathogen is recognized as a persistent soil-borne fungus capable of producing thick-walled structures that allow it to survive under adverse environmental conditions for prolonged periods.

Primary hosts for this fungus include Eucalyptus species and several ornamental plants commonly raised in controlled nursery environments. Because these plants are often grown in high-density conditions, the pathogen can spread rapidly from a few infected plants to the entire population if left unmanaged.

Symptoms typically start as small, irregular, dark-brown spots on leaves, which may enlarge and lead to defoliation. Stem lesions appear as sunken, necrotic tissues that eventually girdle the stem, leading to the collapse and wilting of the upper foliage. Root systems of infected plants often show signs of brown rot and decay, hindering water and nutrient uptake.

Optimal conditions for disease development include high humidity, lack of air circulation, and warm temperatures ranging from 20°C to 28°C. The fungus produces abundant conidia on the surface of infected tissues, which are easily disseminated via water splashes, contaminated potting media, and infected nursery equipment or rootstock.

Managing Cylindrocladium clavatum requires an integrated approach focusing on strict sanitation and environmental control. Growers should prioritize the use of disease-free propagation material and sterile substrates. Fungicide treatments, particularly those with systemic properties, are effective when applied preventively. Regular monitoring for the early signs of blight is essential to protect nursery stocks from widespread infestation.