Growth of Three Shade Tree Genera as Influenced by Irrigation and Nitrogen Rates

The influence of N rates and irrigation on shoot growth and trunk diameter were evaluated for red maple (Acer rubrum, L. ‘October Glory’), pin oak (Quercus palustris Muenchh) and dogwood (Cornus florida L. ‘Barton’). Irrigation increased shoot growth and trunk diameter for all 3 species during the first 2 growing seasons. Tree height and trunk diameter at the end of the third growing season were also greater for irrigated trees. Increasing the N levels from 168 to 329 Kg N/ha (150 to 300 lb N/A) resulted in a decrease in trunk diameter the first year and a decrease in shoot growth the second year in ‘October Glory’ maple. No significant differences in oak growth due to N rate were observed. Shoot growth and trunk diameter for dogwood were greater at 329 kg N/ha (300 lb N/A) than at 168 kg N/ha (150 lb N/A) only the first year. Neither height or trunk diameter at end of the third year were significantly increased from applying the higher level of N for any of the genera.