The 2012 ASHS Annual Conference

The fast growing demand for organic strawberries in recent years has led to a rapid increase of organic strawberry production. Despite the expansion of organic strawberry acreage, one of the challenges facing organic strawberry growers is the lack of suitable cultivars selected or developed specifically for organic conditions. The objective of this study was to assess strawberry cultivar performance in response to organic vs. conventional nutrient management. Two strawberry cultivars including Treasure and Treasure Harvest and 3 advanced selections AA1, AA2, and AA3 were included in this greenhouse experiment. Strawberry plug plants were transplanted into 3.8-L plastic pots and grown with either organic or conventional fertilizer during Oct. 2011 to Feb. 2012. The organic fertilization treatment consisted of a mixture of processed, pasteurized poultry litter 3–0.9–2.5 (N–P–K) and Nature Safe organic fertilizer 10–0.9–6.6 (N–P–K), while synthetic fertilizer 16–1.8–6.6 (N–P–K) was used in the conventional fertilization treatment. Preplant application and side dressing of fertilizers were made in both organic and conventional treatments. A randomized complete block design with a two-way factorial treatment structure was used. There were 4 replications with 5 plants of each cultivar/advanced selection in each fertilization treatment per replication. Total marketable fruit yield per plant was significantly higher in ‘Treasure Harvest’ than ‘Treasure’ and the 3 advanced selections, whereas it did not differ significantly between organic and conventional fertilization treatments. ‘Treasure Harvest’ showed significantly greater total leaf area and shoot dry weight at final harvest than other strawberries, while ‘AA3’ and ‘Treasure Harvest’ had the highest root dry weight at final harvest. Varietal differences were also observed in total soluble solids content. ‘AA2’ and ‘AA3’ exhibited similar levels of average total soluble solids content which were significantly higher than that of ‘AA1’ and ‘Treasure Harvest’. The fertilization treatment did not significantly affect the total soluble solids content of strawberry fruit. Twospotted spider mite infestations occurred in most of the strawberry plants; however, ‘Treasure Harvest’ demonstrated the lowest level of infestation as indicated by the percentage of infested leaflets per plant. The less severe infestation of twospotted spider mites in ‘Treasure Harvest’ probably contributed to its higher marketable fruit yield observed in this study. Although organic fertilization did not differentially impact strawberry cultivar performance in comparison with conventional fertilization, the effect of nutrient management and availability on organic strawberry production deserves further studies especially under field conditions.