Blueberry fruit quality and yield as affected by fertilization

The effects of timing of fertilizer applications on fruit quality and yield of highbush blueberry (Vaccinium corymbosum L.) cultivar 'Duke' were evaluated during the summers of 2000 - 2003. Treatments included a split application of 10-10-10 when uptake is more efficient, i.e. early petal fall and pre-harvest and were compared to the control, a split application of 10-10-10 at bud swell and post-bloom. Additionally, fertilizer applications were made via trickle irrigation (fertigation) from early petal fall through pre-harvest and compared to the standard 10-10-10 application at bud swell and post-bloom. Fruit size, fruit firmness, leaf nutrient levels, and yield were analyzed utilizing a randomized complete block design. Fruit was harvested once a week. The 2002 data showed that yield was significantly increased with both the petal fall/pre-harvest and the fertigation treatments when compared to the control. In addition, there were significant differences in fruit firmness between treatments. Leaf nutrient levels indicate a greater efficiency of uptake with the treatments initiated later than the control. Additionally, berries that were fertigated were 14% firmer than control berries. These results, coupled with fertilizer recommendations based on leaf analysis and a greater awareness of the role of the proper soil pH have changed the way highbush blueberries are fertilized in New Jersey.