Energy dispersion X-ray fluorescence technique (EDXRF) was employed to study the effects of the fumagina disease through the
elementary chemical composition of leaves. The experimental setup consisted of a Mo X-ray tube (Kµ=17.44 keV) with Zr filter and a Si(Li) detector. The measurements were performed with infected and healthy leaves of citric
plants. The elements Ti, Mn, Fe, Cu and Zn were quantified. For all the elements of interest the measured detection limit
was at the order of mg . g-1.