Grow Tubes Reduce Root and Crown Growth but Not Early Production during Establishment of Highbush Blueberry

Abstract

Grow tubes are sometimes used in blueberry (Vaccinium corymbosum L.) to establish plantings or replace dead plants in older fields. Two experiments were conducted at a commercial farm to evaluate the effect of various grow tubes used during planting establishment of highbush blueberry cultivars. The treatments in the first experiment were cultivar (‘Aurora’, ‘Elliott’, ‘Liberty’) and grow tube treatment (no tube, control; opaque cardboard tube in the first growing season; and opaque plastic tube in the first season or first through the second season). The treatments in the second experiment were cultivar (‘Aurora’, ‘Elliott’, ‘Liberty’, ‘Ozarkblue’) and grow tube treatment (control; translucent plastic; opaque plastic; and wire mesh tube over plants in the first growing season). The presence of a grow tube from spring to fall of the first growing season decreased crown dry weight (DW) by an average of 37% to 50% and root DW by 30% (all except translucent plastic in Expt. 2) and increased the aboveground:belowground DW ratio relative to the control by an average of 34% to 67%, depending on the experiment. Plants grown in tubes were taller, had a narrower canopy, and had fewer whips, likely a response to low light levels inside the tubes; the fewest whips were found in the opaque plastic or cardboard tubes and the most in the translucent plastic tube with an intermediate response in the wire mesh tube. Removal of grow tubes during the summer led to plant damage from sudden sun exposure. The opaque grow tubes (present in Year 1) reduced yield/plant in Year 2 for ‘Elliott’ and ‘Liberty’ (cardboard tube only) but not ‘Aurora’. Pruning plants to allow for limited early fruit production (≈0.6 kg/plant) in Year 2 did not reduce yield in Year 3 (≈2.7 kg/plant). Whereas grow tubes reduced root and crown growth in the first season, there appeared to be no longer-term adverse effect on aboveground plant growth or yield.