Colletotrichum truncatum transmission via lima bean seeds

Abstract

Anthracnose is the primary disease in Phaseolus lunatus cultures, causing severe losses. Inoculation techniques are vital for assessing genotype resistance and control methods at the early stages of seedling development. This study aimed to compare inoculation methods and exposure times of a lima bean seed variety to Colletotrichum truncatum using a completely randomized 4x5 factorial design with five replications. Seed inoculation methods by direct contact with mycelium, mannitol water restrictor, and sucrose water restrictor and immersion in conidia suspension were compared and submitted to substrates containing the developed pathogen or not at exposure times of 0, 36, 60, 84, and 108 hours. Evaluations were made by analyzing the severity, incidence, and disease index for anthracnose and seedling physiological quality under greenhouse conditions. The inoculation method by direct contact with sucrose solute for 36 hours was the most suitable for C. truncatum inoculation in lima bean seeds, providing a higher transmission rate but slightly affecting their physiological parameters. C. truncatum damage to lima bean seed performance increased with longer exposure times, regardless of the inoculation method.