Per Tree Lbs. Per Tree Gal. Favorable responses have been observed in San Diego County and in Rancho California. There are no specific symptoms for the initial stages of phosphorus deficiency. A deficient tree generally tends to be stunted and totally lacks vigor.
Twig dieback is common in moderate to extreme cases.
The tree canopy is open and sparsely foliated with little leaves. The presence of little leaves could lead one to believe it is zinc deficiency, except that the characteristic leaf mottling is normally absent. These groups of trees most likely indicate that the entire grove is borderline for phosphorus and would benefit from phosphorus application. Before the decision is made to treat with phosphorus, confirmation of phosphorus deficiency by leaf analysis is strongly recommended. If the leaf analysis shows leaf concentrations of Control Control can be achieved by application of a liquid source of phosphoric acid in the irrigation system or as a soil band of dry fertilizer applied in the irrigation wetting pattern.