12 



Foliar applications of nutrients for tree fertilization ap- 

 pear to have only limited usefulness. In our tests, trees 

 given the foliar spray did not make substantially greater 

 growth than unfertilized trees, and the color of the foliage 

 of the treated trees was not significantly better than that 

 of unfertilized trees. 



Several considerations favor shade tree fertilization. The 

 cost of the fertilization is negligible in comparison with 

 the high aesthetic value homeowners place upon their 

 trees. Lawns are not injured by the fertilization; in fact, 

 the growth of grass is stimulated by the use of fertilizers 

 applied at rates required to obtain good growth in trees. 



Trees of some species that have few desirable qualities 

 other than that they grow rapidly are now planted by some 

 homeowners and municipalities because quick replacement 

 of shade is demanded. With additional information on 

 shade tree fertilization, it should be possible to make 

 greater use of some tree species that heretofore have not 

 been used extensively because they are considered slow- 

 growing. Some of these species may be used as replace- 

 ments of American elms killed by the Dutch elm disease. 

 Slow-growing tree species having otherwise desirable char- 

 acteristics may be planted and, through fertilization, stimu- 

 lated to grow faster. 



ACKNOWLEDGMENTS 



Acknowledgments are made to staff members of the 

 Illinois Natural History Survey: Dr. J. Cedric Carter, who, 

 as Plant Pathologist and Head of the Section of Applied 

 Botany and Plant Pathology, provided administrative su- 

 pervision and made a critical review of the manuscript. 

 James S. Ayars, Technical Editor, edited the manuscript, 

 Wilmer D. Zehr, Assistant Technical Photographer, made 

 most of the photographs for this publication, Dr. J. L. 

 Forsberg, Plant Pathologist, made others, and William L. 

 Taylor, Assistant Technical Editor, prepared the drawing 

 for Fig. 4. Webster R. Crowley, Jr., provided Fig. 1. 



Special thanks are given to Gary L. De Barr, Research 

 Assistant, for assistance in a portion of the field work, and 

 to Mrs. Betty Nelson, who typed the manuscript. The 

 manuscript has benefited from the reviews of Dr. J. B. 

 Gartner, Professor of Floriculture, Horticulture Depart- 

 ment, University of Illinois, and Dr. S. W. Melsred, Pro- 

 fessor of Soil Chemistry, Agronomy Department, Univer- 

 sity of Illinois. 



ABSTRACT 



Fertilization experiments were carried out in 1963 

 and 1964 on pin oak, white ash, and honey locust in block 

 plantings established for 7 years at the Morton Arboretum, 

 I isle, Illinois. Sixteen fertilizer treatments (each of the 

 treatments a different combination of fertilizer and method 

 of application) were used on each tree species. Four 



methods of application were used: surface broadcasting, 

 placement of dry fertilizers in holes made in the soil, in- 

 jection of liquid fertilizers into the soil, and spraying of 

 foliage. The following nutrient elements or combinations 

 of elements were used: N, PK, NPK, and NPK plus 

 minor or trace elements. 



The addition of nitrogen to the soil at the rate of 6 

 pounds per 1,000 square feet resulted in tree circumference 

 increases greater than the increases in untreated controls: 

 39% greater in white ash, 52 r r greater in pin oak. and 

 73 r i greater in honey locust. The application of phos- 

 phorus and potassium to the soil did not bring about a 

 significant growth response; nor did a combination of 

 phosphorus, potassium, and nitrogen produce a response 

 that was significantly greater than that produced by nitro- 

 gen alone. The addition of minor elements to NPK 

 produced no significant growth response. 



The three methods of soil application appeared to be 

 about equally effective, with minor variations among the 

 tree species. Surface application produced the greatest 

 amount of total growth on trees of the three species con- 

 sidered together. Foliar sprays did not produce a sub- 

 stantially greater growth than the growth of unfertilized 

 controls. 



LITERATURE CITED 



Anonymous. 1959. Mineral nutrition of trees, a symposium. 



Duke Univ. School Forest. Bui. 15. 1S4 p. 

 BEILMAN, A. P. 19m. How to feed a shade tree. Missouri 



Bot. Garden Bui. 22 : 1 1 3-126. ( Article signed merely A.P.B. 

 BOYNTON. DAMON. 195-1. Nutrition by foliar application. 



Ann. Rev. Plant Physiol. 5:31-5-1. 

 Chadwick. L. C. 1935. The fertilization of shade trees in the 



nursery. Amer. Soc. Hort. Sci. Proc. for 1934, 32:357-360. 

 . 1937. Fertilizer trials with shade trees in the nursery. 



Amer. Soc. Hort. Sci. Proc. for L936, 34:664 



1940. Fertilization of woody ornamental plants. Ohio 



Apr. Exp. Sta. Bimonthly Bui. 25:89-96. 

 . Paul E. Tilford. and Charles F. Irish. 



study of some methods of fertilizing shade trees. Amer. Soc. 



Hort. Sci. Proc. for 1949. 55:519-526. 

 JACOBS. HOMER L. 1929 Fertilization of shade trees. Part I: 



Fall vs. sprint: fertilization. Davey Tree Expert Co. ( Kent. 



Ohio Res. Dep. Bui. i. 28 p. 

 Pirone. P. P. 1951. Foliage application of nutrients. National 



Shade Tree Conf. Proc. 27:23 — 35. 

 Stoeckeler, Joseph H., and Harold F. Arnemam 1960. 



Fertilizers in forestry. Advances in Agron. 12:127 — 195. 

 Wascher. H. L.. P. T. Yealf. and R. T. Odell. 1962. VTill 



County soils. 111. Apr. Exp. Sta. Soil Rep. 80. 10- 

 WlKLE, JACK 1963. Some comments and questions on soil 



improvement and fertilization for shade trees. Arhorist's 



News 28(8-9) :61-69. 

 Wiiiwii; S H. AND F. G. TEUBNER. 1950. Foliar absorption 



ot mineral nutrients. Ann. Rev. Plant Physiol. 10:13 ; - 

 W'vman. Donald. 1936. Growth experiments with pin oaks 



which are growing under lawn conditions. Cornell Univ. 



Agr Exp. Sta. Bui. 646, 23 p. 



(10314— 6M 



>I4 



