PREVENTING TIPBURN ON STRAWBERRY CULTIVAR 'CLERY'

Abstract

Tipburn of strawberry leaves and strawberry fruit calyx is caused by a local deficiency of calcium in the strawberry plant. Ca plays a key role in the integrity of the cell wall. Young leaves emerge from the crown and an insufficient uptake and transport of calcium throughout the plant results in the weakening of cells in the border of leaf blades and the tips of the calyx of emerging flowers. Tipburn results in a crop with wrinkled leaves, a decrease in photosynthetic activity and a possible production loss. The dried tips of the calyx result in a direct devaluation of the strawberry fruit. The cultivar ‘Clery’ is primarily planted in Belgium in the earliest cultivation systems. ‘Clery’ is planted in December on support structures in glasshouses and is strongly forced to grow through heating and artificial day length prolongation. The high growth rate increases the demand for calcium and the incidence of tipburn. Foliar application of calcium as well as additional calcium mixed in the substrate had no effect in decreasing tipburn. Tipburn is not caused by the availability of calcium, but rather by the poor mobility of calcium throughout the plant. The absence of transpiration by the young unfolded leaves makes them unable to compete for calcium supply with the full grown leaves. By cutting leaf discs of the full grown leaves, a reduction of leaves and flowers damaged by tipburn could be realized. Emerging leaves and flower heads seem to depend solely on the supply of calcium by root pressure flow. The forced conditions in the greenhouse result in a longer period of transpiration, a decrease of root pressure buildup and therefore a higher risk of tipburn. Stimulating the buildup of root pressure by creating humid conditions during the evening and night by a high pressure fogging system, completely prevented tipburn. For further optimization it is necessary to prevent faint petioles in the morning and the consequential production loss.