Table 1.

Response of six tree species on the University of Illinois campus to treatments with ferric citrate powder.

Tree species	Number of trees	Average dbh (inches)	Color Rating³
Tree species	Number of trees	Average dbh (inches)	Initial	Final	Difference
Pin oak^¹	5	6	2.2	7.9	5.7
Control	3	6	2.2	2.8	0.8
Pin oak^²	8	16	5.2	6.9	1.7
Control	10	15	3.8	3.6	— 0.2
Bald cypress^²	5	18	4.3	7.7	3.4
Control	3	24	3.0	3.7	0.7
Red oak^²	3	8	5.2	7.3	2.1
Control	2	10	7.0	7.0	0.0
Swamp white oak^²	15	6	6.6	7.0	0.4
Control	13	6	7.1	6.1	— 1.0
Sweet gum^²	7	10	6.5	8.4	1.9
Control	4	17	6.0	6.3	0.3
American sycamore^²	2	12	5.0	6.3	1.3
Control	3	15	6.0	7.0	1.0

↵¹ Treated July 24, 19 74; color rating taken at end of two growing seasons (early September, 19 75).
↵² Treated June 1 7-19, 1975; color rating taken at end of first growing season (early September, 1975).
³ Color code: 1-6, shades of yellow; 7-10, shades of green; 10, dark green.