Weed Hosts of the Sugarcane Root Rot Pathogen, Pythium arrhenomanes.

Area of Science:

• Plant Pathology
• Agronomy
• Weed Science

Background:

• Pythium root rot is a significant disease affecting sugarcane production.
• The role of common weed species as alternative hosts for the pathogen Pythium arrhenomanes is not fully understood.

Purpose of the Study:

• To investigate the susceptibility of prevalent Poaceae and Cyperaceae weeds in sugarcane fields to Pythium arrhenomanes.
• To assess the potential of these weeds to serve as hosts and contribute to the epidemiology of Pythium root rot in sugarcane.

Main Methods:

• Greenhouse experiments were conducted using steam-treated soil infested with Pythium arrhenomanes.
• Various weed species (e.g., johnsongrass, itchgrass, bermudagrass) were grown and inoculated.
• Root colonization, symptom severity, and growth reduction were evaluated.
• Weeds collected from sugarcane fields were also assessed for natural P. arrhenomanes colonization.

Main Results:

• Multiple weed species, including johnsongrass and itchgrass, were infected by P. arrhenomanes.
• Infection levels and disease severity varied significantly among weed species.
• Johnsongrass and itchgrass showed the highest root colonization, while browntop panicum, goosegrass, and Italian ryegrass showed the lowest.
• Weeds from sugarcane fields exhibited moderate to high colonization frequencies, but generally low colonization extent, except for johnsongrass.

Conclusions:

• Weeds prevalent in sugarcane fields can act as hosts for Pythium arrhenomanes.
• These weed hosts may play a crucial role in the survival and spread of Pythium root rot pathogen, influencing disease management strategies in sugarcane.