The development and evaluation of DRIS (Diagnosis and Recommendation Integrated System) norms for apple leaf composition

Due to the dynamic nature of the SLW (specific leaf weight), production figures are necessary for the development of DRIS norms.  These norms are then expressed as regressions.  Norm-regressions were developed for normal to high yielding orchards.  The norm-regressions were generally strong for Golden Delicious and Granny Smith but were mostly very weak for Top Red and Royal Gala. Orchards were selected for the evaluation of DRIS norms.  A complete evaluation of DRIS norms could not be done since orchard yield data is currently not available.  It currently appears as if the DRIS norms differ significantly from current leaf norms.