Foliar application is the most effective way to increase calcium for the current growing season. Use calcium chloride when tissue analyses show a high nitrogen content. Foliar treatments should be made at two-week intervals starting at first cover spray and ending two weeks prior to harvest. If leaf burn is observed, reduce the rate of calcium applied. For new orchards, phosphorus amendments should be incorporated deeply into the soil before trees are set.
Deep incorporation enhances root growth and uptake efficiency.
On established orchards, however, where incorporation is not practical, surface applications may be appropriate. Since phosphorus does not leach in soils, it will accumulate with time from fertilizer applications and foliage recycling. Potassium applied in excess of soil test recommendations can cause competition with calcium uptake and increase the potential for bitter pit. Therefore, potassium application rates should be based solely on soil and plant analysis. Growers should not make blanket applications of high-potassium fertilizers.