Mineral concentrations in individual 'd'Anjou' pear fruit with and withoutcorkspot

Individual 'd' Anjou' pear fruit with and without corkspot were analyzed fo r N, K, P, Mg and Ca concentrations over a two year period to determine if the disorder could be separated on the basis of mineral concentrations or N :Ca ratios. Two sites were sampled in 1989 and 12 sites in 1991. Although n o critical mineral concentration or N:Ca ratio was found that would entirel y separate populations of either normal or disordered fruit, a peel tissue N. Ca ratio of 6.3, suggested by the literature, correctly distinguished ap proximately 70% of fruit in each category. Logistic models developed by ste pwise regression indicated that the best models for each site were not the same and did not always contain N or Ca. The logistic models correctly pred icted approximately 83% of the fruit in each category.