A COMPARISON OF AGRONOMIC TREATMENTS TO IMPROVE AVERAGE BERRY SIZE IN EVERBEARING STRAWBERRIES (FRAGARIA × ANANASSA)

Abstract

The total area of strawberry grown in the UK is nearly 5000 ha producing 110,000 t (DEFRA Basic Horticultural Statistics, 2011) of which approximately 40% is of everbearing cultivars. As everbearers are a very important component within the UK strawberry industry, it is essential to maximise the yield of class 1 berries for the growers. In many everbearer cultivars the average fruit size decreases as the season progresses. In 2010 and 2011 two trials were conducted to determine whether agronomic treatments could improve the average fruit size at harvest. The cultivar used for the study was ‘Finesse’, which is a recent release from East Malling Research that is becoming an important cultivar in the UK market place. Study 1 conducted in 2010 was designed to determine whether the removal of leaves and/or the removal of blooms could influence fruit size in the latter stages of harvest. In this study the oldest leaves of ‘Finesse’ were removed to a leaf area index (LAI) of 3.0 in an attempt to eliminate older, less-efficient leaves thereby diverting assimilates to enhance fruit size, while maintaining a full canopy of newer and more productive leaves. There was anecdotal evidence from UK growers that this treatment had been effective in some everbearing cultivars but this study concluded that a LAI of 3.0 and de-blooming three weeks after planting had the effect of reducing overall yield, due to a reduction in fruit size. Based on the same principle of relocating assimilates, study 2 conducted in 2011 compared four further treatments, which included a control, de-flowering at planting, picking only large berries followed by truss removal, and removing whole trusses from the plants. Harvesting continued until end of October 2011. Results showed that not harvesting the smaller berries increased significantly the percentage of larger fruit (above 45 mm) produced per plant. The production of larger berries in that treatment was also shifted towards the end of the harvest but that result was not consistent across the four replications.