Six years of strawberry trials in commercial fields demonstrate that an extract of the brown seaweed Ascophyllum nodosum improves yield of strawberries

Strawberry (Fragaria ananassa) growers are often looking for sustainable products to enhance the overall health and yield of their crop. In trials over six years, one summer and five winter studies, conducted in the Oxnard area of California, it was shown that soil drip-tape applications of seaweed extract (Ascophyllum nodosum) enhanced yield of strawberries by an average of 4394 kg ha(-1) compared to the control. This improvement in yield is likely due to improvements in early growth and crown development as were seen in the five years where it was evaluated. Two-spotted spider mite (Tetranychus urticae) populations were high enough to rate in two of the trials with Acadian LSC suppressing mites in both trials. Charcoal rot caused by the pathogen Macrophomina paseolina was present in the fourth year of this study (2013-2014). The seaweed extract treated plots had less mortality due to this disease compared to the control (27.4 vs. 16.6% plant mortality). Lastly, in the first year study there were high soil sodium levels and the seaweed extract treated plots had less phytotoxicity as well as lower sodium levels in the leaves. These results indicated that Ascophyllum nodosum extract significantly improves yield of strawberries however the mode of action is likely multifaceted and may involve improvements in growth, tolerance to environmental stresses, and tolerance to biotic stresses.