Wind damage to kiwifruit (actinidia chinensis planch.) in relation to windbreak performance

Losses of export-quality kiwifruit (Actinidia chinensis Planch.) attributable to wind damage increased with distance downwind of both natural and artificial windbreaks. These effects occurred on standard ‘T-bar’ trellised vines during a particularly windy season, within shelter spacings which the literature suggest should achieve adequate reductions in windspeed. Distance from the nearest upwind natural shelterbelt explained 57%of the variation in exportable yield per vine. Major losses resulted from frictional marks caused by fruit rubbing against each other and against plant canes. Mean proportions of exportable sized fruit rejected for this reason varied from 3–10%(for rows adjacent and to the lee of natural windbreaks) to 30–44%(3–4 rows downwind of artificial shelter). Trends in foliar damage and vegetative growth were similar to those observed in wind-rub damage. On rows partially shaded by natural shelter, up to 40%of the total fruit load did not reach export size because of poor pollination. In comparison, a property using a Tatura trellis system with minimal internal shelter lost only 1%of its fruit from wind-rub damage. The success of this trellis may be related to the onset of skimming flow because of the high density of roughness elements.