Bacterial Stalk Rot (Dickeya zeae) and Its Impact on Maize: The Emerging Silent Invader

Bacterial stalk rot caused by Dickeya zeae has emerged as significant threat to maize production globally. This pathogen previously known as Erwinia chrysanthemi pv zeae, is very notorious for its ability to cause severe yield losses, sometimes upto 98.8% depending on the climatic conditions. This disease is particularly prevalent in tropical, subtropical and temperate regions, thriving in high temperature and moisture conditions. Dickeys zeae has been characterized by morphological, molecular, physiological methods and virulent factor is found out to be pectolytic enzyme responsible for degradation of pectin present in cell wall component of plant. Bacterium survives in host debris and serves as primary source of inoculum. Symptoms can appear at any stages of crop growth from sowing to harvesting. Water soaking and rotting of basal stem mainly leaf sheath which emits foul smell. This pathogen has broad host range including sorghum, maize, rice, tomato, potato, brinjal, chilli and other grasses which makes its very difficult to manage this disease. It found to be severe in heavy rainfall area and stagnant water conditions by creating systemic disease infecting vascular tissues of plant. This pathogen can survive upto 3-6 months in soil having maize crop residues. Current control measures such as cultural, biological, physical, mechanical approaches have proven ineffective. No chemicals are found to be completely effective against this, although some are commercially available. This pathogen is soil borne and destructive in nature, complete resistance has not been identified. Therefore, identification and development of resistant cultivars are great strategy to combat bacterial stalk rot. Among all control measures, host plant resistance will be most economical and time consuming. Bacterial stalk rot is destructive pathogen causing great economic losses hence requires great attention to manage it effectively.