Exserohilum root rot of maize

The causative agent of this disease is the fungus Exserohilum pedicellatum, a significant soil-borne pathogen primarily affecting the root system and crown of maize plants. This fungus acts as a parasite that disrupts the integrity of vascular tissues, leading to systemic weakness of the crop and reduced water and nutrient uptake.

The primary host for Exserohilum pedicellatum is corn (maize), although the pathogen has been identified in various other grass species. The ability of the fungus to survive in plant debris and soil allows it to persist in agricultural fields for several years, posing a continuous threat to susceptible crops if proper sanitation is not maintained.

Symptoms of the disease include browning and necrosis of the primary and secondary roots. Affected plants often show stunted growth, chlorosis of the lower leaves, and poor vigor. In severe cases, the structural decay of the crown tissue results in lodging, where the stalk becomes unable to support the weight of the plant, especially during windy conditions.

The development of the fungus is favored by high soil moisture content and moderate temperatures, which are typical for the early stages of the growing season. Poor drainage and compacted soil structures exacerbate the infection, as they restrict root health and create a favorable environment for the proliferation of fungal spores and mycelia.

Management strategies focus on reducing the initial inoculum and enhancing plant resistance. Key practices include crop rotation to interrupt the life cycle of the pathogen, the use of certified, fungicide-treated seeds, and the implementation of soil cultivation techniques that improve aeration. Ensuring balanced fertilization also helps plants develop stronger root systems that can better withstand infection.