The effect of nitrogen and boron fertilizer applications on leaf levels, yield and fruit size of the red raspberry

A factorial fertilizer experiment with four N and two B levels was conducted on red raspberry over a 5 year period to determine the effects on leaf element content, fruit size and fruit yields and to determine standard leaf levels for N and B. Nitrogen application increased leaf N, reduced leaf B, increased fruit size and had no effect on yield. Boron application increased leaf B, reduced yields in 2 of the 5 years but had no effect on fruit size. Nitrogen application increased leaf Mn levels but had no effect on leaf element content of K, P, Ca, Mg, Fe, Cu, B or Zn. Boron application had no effect on leaf element content. Leaf N content of the primocanes was not related to following year yields for any of the years. Yields were linearly reduced by primocane leaf B in 1 year. Definitive optimum leaf levels for N and B for red raspberry could not be determined since all levels measured seemed to be adequate, however, it is believed that the optimum value for N is under 2.4% and for B under 25–35 ppm.