Treatment of chlorotic pin oak in 1977.
| Treatment | Number of trees | Color rating1 | Twing growth (inches) 1978 | |||
|---|---|---|---|---|---|---|
| May 1977 | July 1977 | July 1978 | July 1979 | |||
| Ferric citrate2 | 32 | 4.5 | 7.4 | 7.7 | 6.5 | 6.8 |
| Ferric ammonium citrate3 | 14 | 5.3 | 7.1 | 7.1 | 6.4 | 6.9 |
| Ferric ammonium citrate + NPK4 | 14 | 4.6 | 7.0 | 7.1 | 7.2 | 6.6 |
| Ferric ammonium citrate + N5 | 10 | 4.6 | 5.9 | 5.7 | 5.3 | 5.7 |
| NPK6 | 10 | 6.2 | 6.6 | 7.1 | 6.6 | 4.6 |
| NPK + slow-release N7 | 6 | 5.2 | 5.8 | 6.6 | 5.4 | 4.8 |
| N (slow-release)7 | 11 | 6.0 | 6.1 | 6.2 | 5.9 | 4.3 |
| Control | 12 | 5.7 | 6.3 | 6.3 | 5.8 | 4.3 |
Average tree size: 13.2 in dbh (range 4-24 in).
↵1 Color code: 1-6, shades of yellow: 7-10, shades of green; 10, dark green.
↵2 Purified powder form, 1 ½ g/ho)e, holes 4 in (10 cm) apart.
↵3 Medicap Fe28, size 0, 3/8 in (1.1 cm), trees 4-11 in (10-28 cm) dbh; size 000,0.5 in (1.27 cm) in larger trees.
↵4 Medícap formulation of Fe + soluble NPK, size 000 in trees 4-11 in dbh and size 11/16 in (2.1 cm) in larger trees.
↵5 Medicap formulation of Fe28 and slow-release N, size 0 in trees 4-11 in dbh and size 000 in larger trees.
↵6 Medicap formulation with soluble NPK alone, size 0 in trees 4-11 in dbh and size 000 in larger trees.
↵7 Medicap formulation with slow-release N only, size 0 used in trees 4-11 in dbh and size 000 in larger trees.
8 Medicap formulation of slow-release N, size 000 used in trees 4-11 in dbh and 11/16 in cartridge in larger trees.