The southern highbush blueberry was bred from native blueberries and northern highbush blueberries by UF researchers to produce low-chill high-quality blueberries. Now researchers are going back to our native blueberries for another reason – tree form blueberries. Vaccinium arboreum is a native blueberry with not so great fruit, but it has a form that might make a great rootstock. A rootstock is the root system of a plant that has the desired characteristics for a root suited to the soils and cultural system used, while the scion is grafted to the top to provide the shoot part of the plant selected for best fruit quality. This is the way fruit growers get the fruit quality you like produced in the top with the roostock best suited to their production.
Why use a rootstock?
Southern highbush blueberries (SHB) require an acid, organic soil that is expensive to try to reproduce in our sandy soils. Growers usually plant into raised beds of mounded pine bark fines (small pieces of pine bark). Vaccinium arboreum does not require soil amendments since it is adapted to our sandy, high pH soils. SHB grafted onto Vaccinium arboreum should be able to be grown without soil amendments and there is another perk. A tree form with a single trunk will allow over-the-row harvester equipment to more efficiently harvest the fruit.
UF/IFAS researchers planted grafted and own-rooted ‘Farthing’ and ‘Meadowlark’ at two locations in north central Florida. Plants were planted in pine bark-amended soil or nonamended soil to test the effect of rootstock on growth. Yield, canopy volume and berry quality were measured over four years.
Canopy volume was greater on amended soils than nonamended soils for both cultivars. Yield was greater in grafted plants at both locations for both cultivars regardless of soil amendments. Grafted plants yielded more than own-root plants on nonamended soils indicating that using a rootstock may decrease the need to use pine bark amendments. Fruit on grafted plants was generally larger with no negative effects on soluble solids, titratable acidity, or firmness. However, the impacts of grafting on the lifetime of the planting and an economic analysis of the two systems is needed.
Rebecca L. Darnell, Jeffery G. Williamson, Deanna C. Bayo and Philip F. Harmon. 2020. Impacts of Vaccinium arboreum Rootstocks on Vegetative Growth and Yield in Two Southern Highbush Blueberry Cultivars. HortScience 55(1):40-45.