Sulfur deficiency has never been documented in California stone fruit orchards. This is probably because S is found in many fertilizers and is abundant in most soils. In addition, it is found in the atmosphere and is carried into the soil by rain. Sulfur is also recycled efficiently by senescing leaves.
In other crops, sulfur deficiency symptoms are similar to nitrogen (N) deficiency. In our sand tank experiment, we found a very close relationship between S and N in mid summer leaf samples (see graph at right). We hypothesize that this relationship is controlled by nitrogen. Thus, the correction of low or deficient S levels is to add more nitrogen fertilizer. This relationship has only been established for Nemaguard and may not be true for other rootstocks.