Foliar boron increases berry number and yield of two highbush blueberry cultivars in Missouri¹

Abstract

Abstract Foliar applications of boron (B) have been shown to increase fruit set and yield of several woody fruit species, but there have been no reports of foliar B effects on blueberry (Vaccinium corymbosum L.). The objective of this study was to determine if foliar B would decrease tip dieback, alter yield components, and increase berry yield of blueberry. Blueberry plants (cvs. Collins and Blueray) were grown on a Menfro series soil (fine‐silty, mixed, mesic Typic Hapludalf) with the two cultivars planted in alternate rows. Five uniform plants from each row were either treated with foliar B plus surfactant or untreated. Foliar B was applied in the fall prior to each harvest year, 1990 through 1993, and additional foliar B was applied in the spring in 1991 through 1993. Foliar B increased blueberry weight/plant by 10% over the four‐year period. The increase in blueberry yield was a result of a 12% increase in number of berries/plant. Yield increase following foliar B treatment was greatest during the first two weeks of harvest for Collins and during the second two weeks for the later flowering Blueray. Following a freeze (‐8°C) at flowering in March 1990, tip dieback for Collins was 75% greater in control plants than for plants treated with foliar B the previous fall. The reduced tip dieback in 1990 following foliar B treatment resulted in the largest percent increase (31%) in blueberry yield during the four‐year study. However, the actual yield increase in 1990 of 201 g/plant was very similar to the four‐year average increase of 238 g/plant with foliar B treatments. When the yield increase per plant is multiplied by the number of plants typically grown on a hectare of land (2500), it is apparent that foliar B applications for Collins and Blueray blueberries in the Midwest would be profitable.