Relationships between the incidence of fire blight in ‘Golden Delicious’ apple trees and nutrient imbalance indices

The multivariate compositional nutrient diagnosis (CND) was considered to evaluate the nutrient imbalance causing fire blight development in ‘golden delicious’ apple. The CND norms provided for a low-fire blight severity subpopulation was V*N = 2.813 ± 0.186, V*P = 0.297 ± 0.147, V*K = 2.660 ± 0.149, V*Ca = 2.442 ± 0.218, V*Mg = 1.188 ± 0.061, V*S = 0.595 ± 0.399, V*Fe = -0.952 ± 0.212, V*Mn = -3.132 ± 0.195, V*Zn = -4.040 ± 0.366, V*Cu = -5.032 ± 0.177, V*B = -3.361 ± 0.120, V*Rd = 6.521 ± 0.128. The corresponding sufficiency ranges of nutrients for for imparting moderate resistance in plant against fire blight were N = 2.309 ± 0.333, P = 0.185 ± 0.016, K = 1.968 ± 0.170, Ca = 1.645 ± 0.430, Mg = 0.453 ± 0.053, S = 0.269 ± 0.086 in percent and Fe = 345.250 ± 76.213, Mn = 60.926 ± 11.724, Zn = 26.368 ± 12.943, Cu = 9.088 ± 1.682, B = 48.603 ± 9.509 in mg kg-1. According to the principal component analysis analysis, leaf Ca, B, S and Zn had a significant effect on the reduction of fire blight severity index.