Development of abamectin loaded lignocellulosic matrices for the controlled release of nematicide for crop protection

Poor mobility of abamectin (Abm) in soil compromises its nematicide efficacy against nematode infestation. In the present work, four lignocellulosic materials (abaca, banana, softwood and hardwood) were fabricated into a handsheet matrix and characterized for loading and controlled release of Abm in a field-deployable matrix. The physical and chemical properties of different lignocellulosic matrices affected its function as a substrate for Abm loading as well as its ability to wrap around the plant seedlings during application. Incorporating Abm into lignocellulosic matrices by physisorption resulted in active matrices with distinct release rates for Abm. The rate of release is shown to be dependent on the matrix’s chemical compositions of cellulose, hemicellulose and lignin and the corresponding distribution of each component within the matrix. The higher lignin content (ca. 10.2 %) in the bulk of lignocellulosic matrix, e.g. mechanical-pulped banana matrix, enabled the slow and sustained release of loaded Abm; providing an efficacious crop protection around the growing tomato seedlings in the root knot nematode-infected soil. Conversely, the decreased lignin content (ca. 3.4 or 4.8 %) in other lignocellulosic matrices due to kraft-pulping and bleaching led to a relative quick release of loaded Abm thus compromising the long-term delivery of Abm to the growing plant root.