Apparent Effect of Zinc Treatment on the Growth Rate of Pecan Production and Yield

Rosette was the major pecan [Carya illinoensis (Wangenh.) C. Koch] production problem prior to the discovery, in 1932, that the disorder was a symptom of Zn deficiency. A comparison of pecan production during the 10-year period prior to 1933 and the 10-year period following 1933 was made to determine the apparent effect of the use of Zn on the growth rate of pecan production from orchards in native and non-native pecan areas. Following the discovery of the cause of rosette, the rate of pecan production increased in non-native but not in native areas. The differential response is proposed to have been due primarily to less severe Zn deficiency in orchards in native than non-native areas. Alternatively, correction of Zn deficiency would have been less likely in native area orchards because of the general ineffectiveness of soil applications of Zn on calcareous soils.