Leaf zinc and copper concentrations of mature pistachio trees in response to fertigation
2000
Kallsen, C.E. | Holtz, B. | Villaruz, L. | Wylie, C.
Mature 'Kerman' pistachio (Pistacia vera L.) trees, located on the west side of the west side of the San Joaquin Valley of California on an alkaline clay-loam soil, were fertigated in 1997 and 1998 with three combinations of zinc (Zn) and copper (Cu) sulfate. Seasonal applications of Zn and Cu were injected at three separate times starting in spring and ending in summer. Efficacy of the treatments were compared by measuring the concentration of Zn and Cu in leaf tissue. Fertigated treatments were compared to trees receiving no supplemental Zn or Cu and to trees receiving a single foliar treatment of Zn and Cu each year. Soil Zn and Cu concentrations increased in the fertigated plots. Plots receiving the highest rates of Zn and Cu showed the greatest increase. However, at the recommended August leaf sampling period, only the foliar treated pistachio trees showed a significant increase in leaf Zn and Cu. The result demonstrate that after two seasons, a foliar application of Zn and Cu in April, two to three weeks after flowering, increased leaf-tissue concentrations of Zn and Cu to sufficiency levels. These foliar applications were more effective than fertigating with Zn and Cu sulfate.
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