Ammonification of cocoa husks as an alternative method to eliminate phytophthorapalmivora inoculum

Abstract

Cocoa husk is produced us a large quantity and may cause a great deal of problem if not managed properly. Cocoa husks buried in soil or laid on the ground are easily infested by Phytophthora palmivora and become a potential source of pod rot disease inoculum. Pod rot is one of the most important diseases in cocoa. The disease is difficult to control because its source of inoculum is difficult to be eliminated. Gaseous ammonia produced from ammonification is known to be toxic to several microbes and may be used to suppress the inoculum potential of P. pabnivora in cocoa husks. The goal of this study was to determine the potential use of ammonification process in the elimination of P. palmivora inoculum. Anunonification of cocoa husk was conducted by mixing cocoa husks with urea in a closed container. Cocoa husks was inoculated with P. palmivora before they were treated with urea. Levels of the inoculum potential were determined using bioassay technique. The level of N total in cocoa husk and the level of N ammonia were determined using Kjeldal technique. From this study it was found that a significant amount of ammonia was produced during ammoniflcation process of cocoa husks with the addition of urea. The ammonia produced eliminated P. palmivora inoculum In cocoa husk tissue within one week at an application level of 0.4% urea. Application of anunonification technique for the eradication of P. palnhlvora was proven to be effective in the field at 2% urea. Besides free from P. pal,nivora, the cocoa husks became 29.5% rIcher of nitrogen after ammonification with 0.2% urea.