Boron Nutrition of Almonds


01 Mar 1997

1996 Annual Interpretive Summary

Boron Nutrition of Almonds and Prunes, 1996

In 1994 a study was initiated to determine the effect of boron (B) nutrition on flowering, fruit set, and yield of almond following a similar (and very successful) study with pistachio. Spraying B at a rate of 1-2 lb Solubor/100 gal on B deficient almond trees increased fruit set by over 20% and yields by 15 lb/tree or 1200-1500 lb/A or 900-1125 lbs of kernels/A in 1995. Of special note is the frequent positive response of almond trees to supplemental B sprays when no B deficiency symptoms were visible. Boron status of the hulls appears to be a better indicator of tree B status than either leaves or bark. Additional positive results were obtained in 1996 in which foliar B sprays increased fruit set by as much as 40% and actual nuts from about 6,600/tree to over 9,000/ tree. Research has demonstrated that even a 10% response to foliar boron is highly profitable. More studies are needed to evaluate the optimal rates and time of B application.

Research initiated in 1996 on prunes produced little useful information. Heavy rains during pollination contributed to poor and highly variable fruit set. Yield and other harvest indices were not assessed. The experiment will be repeated in 1997. CA-13F