- Recent research results in California have shown that foliar applications of Solubor® have increased pistaschio yields.
- The best time for foliar application is from the late dormant to the early bud stages.
- Soil applications of boron are not as effective as foliar applications in supplying sufficient boron for flowering.
Brown, Ferguson, and Picchioni worked with 1,000 pistachio trees in California over a 4-year period to
investigate the role of boron (B) nutrition and review current B recommendations. Cumulative 3-year yields
of pistachio per tree from foliar and soil-applied B are given in the table shown here. Their results show
greater yields were definitely obtained with foliar application of Solubor®. The best application rate shown in
this research was 5 pounds of Solubor® in 100 gallons of water. The best time to use a foliar application was
from the late dormant to early bud stages of development.
Soil-applied B at 2 to 8 ounces per tree affected yields sometimes. Soil-applied B results were not as
consistent, nor as dependable as a foliar application.
Pistachio yield was only one measurement that Brown, Ferguson and Picchioni made on trees. They
documented several influences of foliar-applied B at the critical late dormant to early bud stages. Boron
increased pollen viability, fruit set, and leaf B concentrations, but decreased blanking percentage. All of these
measurements lend support to applying 5 pounds of Solubor®/100 gallons of water per tree at the right time.
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