Fungicidal effect of chitosan on rust inoculated in coffee

Abstract

In Colombia, coffee growing is one of the most important crops, and it is carried out almost in the whole territory, the Arabic Coffea with multiple varieties is grown; the most popular and best flavor is Caturra, which, in spite of its great properties, is attacked by parasitoid fungus Hemileia vastatrix, best known as Rust. This project evaluated the effect of chitosan compound on Hemileia vastatrix fungus, in order to establish fungicide properties of such compound, and consider it as a natural alternative to combat such disease of these plants.At first, chitosan was obtained from shrimp shell Chitin; two kinds of chitosan, one with a deacetylation degree of 28,94%, and other with deacetylation degree of 56,49%, were obtained through a chemical process, which were compared to other two chitosan compounds, one of a low molecular weight (62 cps) and other of molecular middle weight (598 cps). In order to experimentally establish effectiveness of this compound, in its various chemical forms, a germinator was prepared and planted of Coffea Arabic Caturra variety, and a statistical design of random blocks was applied. In addition, the number of diseased leaves of each plant was selected as the variable to be observed during phases infected by Rust. Chitosan compounds were prepared in chloride acid at a 1% and p/v concentration, and applied to each plant by spray. Results showed fungicide activity of the compound when applied as a preventive treatment, that is, previously to be attacked by the disease, and also when applied to Rust infected coffee plants during its initial phase.