The Effects of Autumn Foliar Urea Sprays on Storage Forms of Nitrogen Extracted from Bark and Wood of Apple Shoots

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Abstract
Summary Following the application of urea sprays in October on Golden Delicious apple trees, increased amounts of nitrogen were translocated from the leaves into storage tissues. Trees receiving 10% urea spray had significantly higher levels of total nitrogen in bark in both January and February than either those receiving soil application or control treatments. However, there was also a significant increase in total nitrogen in bark from January to February in the sprayed trees, due mainly to an increase in protein nitrogen in January. In February the soluble nitrogen increased while the protein remained constant. There were no significant differences between treatments in wood total nitrogen levels in January. In February the trees receiving the 10% urea spray had significantly higher total nitrogen levels than those receiving either the soil application or control treatments. In the sprayed trees there was an increase in wood total nitrogen from January to February due to an increase in soluble nitrogen, suggesting a redistribution effect.

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