Treatment of chlorotic sweet gum in 1977.
Treatment | Number of trees | Color rating1 | Twig growth (inches) 1978 | |||
---|---|---|---|---|---|---|
May 1977 | July 1977 | July 1978 | July 1979 | |||
Ferric citrate2 | 11 | 6.3 | 8.7 | 8.3 | 7.4 | 9.0 |
Ferric ammonium citrate3 | 10 | 6.1 | 8.1 | 8.0 | 7.1 | 8.6 |
Ferric ammonium citrate + NPK4 | 10 | 6.7 | 8.3 | 8.0 | 7.8 | 7.8 |
Ferric ammonium citrate + N5 | 10 | 6.3 | 8.1 | 7.9 | 6.7 | 7.1 |
NPK6 | 10 | 6.6 | 8.3 | 8.1 | 7.3 | 6.4 |
NPK + slow-release N7 | 6 | 6.5 | 8.1 | 7.8 | 7.0 | 6.0 |
N (slow-release)7 | 9 | 5.7 | 7.1 | 6.8 | 6.6 | 5.5 |
Control | 11 | 6.4 | 7.6 | 7.7 | 6.6 | 5.2 |
Average tree size: 12.0 in dbh (range 5-33 in).
↵1 Colorcode: 1-6, shades of yellow; 7-10, shades of green; 10, dark green.
↵2 Purified powder form, 1¼ g/hole, holes 4 in (10 cm) apart.
↵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.
↵Medicap formulation of Fe28 and slow-release N, size 0 in trees 4-11 in dbh and size 000 in larger trees.
↵5 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.