Anthracnose of Ti plant

The causative agent of this disease is the fungus Colletotrichum ti, which is a member of the Ascomycota phylum. This pathogen is specifically responsible for anthracnose infections in tropical ornamental plants, most notably within the Cordyline genus. The fungus invades host tissues, leading to necrotic spots and significant foliage damage.

The primary host for this fungus is the Ti plant (Cordyline fruticosa). Due to its commercial popularity as an ornamental plant, Colletotrichum ti poses a significant risk to horticultural nurseries and interior plantscapers, where environmental conditions often favor the rapid spread of fungal spores among dense plant populations.

Symptoms typically present as circular or irregular spots on the leaf surface, which can vary in color from light brown to deep black. Often, these lesions are surrounded by a distinct yellowish or chlorotic halo. Under high humidity conditions, small, salmon-colored or cream-colored fungal spore masses (acervuli) emerge in the center of these lesions. As the infection progresses, leaves may yellow, wither, and eventually drop off.

The development of Colletotrichum ti is heavily reliant on environmental factors such as moisture and temperature. High relative humidity (above 85%) and temperatures ranging from 22°C to 28°C create an ideal environment for spore germination and colonization. Spores are primarily disseminated through splashing water from overhead irrigation, rain, or contaminated garden tools.

Integrated disease management strategies are essential to minimize the impact of anthracnose on ornamental collections:

• Maintain good hygiene by removing all symptomatic leaves and debris from the vicinity.
• Ensure adequate spacing between plants to improve airflow and reduce humidity levels.
• Switch from overhead irrigation to drip or base watering methods to keep foliage dry.
• Apply preventative fungicide sprays containing mancozeb, chlorothalonil, or copper-based compounds.
• Implement strict quarantine protocols for new plant material to prevent the introduction of the pathogen into the greenhouse.