Legal considerations involving chemical control of iron and other deficiencies in plants

Abstract

The authors are aware of four cases of lawsuits involving use of chelating agents in plant nutrition. Three of them involved use of iron. One concerned addition of FeDTPA to nursery trees in containers. No damages were paid and the conclusion was that the reconmendation for use of the chelate was correctly made and no neglect was involved. One case involved foliar application of FeHEDTA to potatoes in July by airplane. The recoitmended rate was used but with less water than recommended to accommodate aerial application. The case was settled out of court. Another case not involving iron chelate was with ZnEDTA and MnEDTA with Fe as FeSOit later as a foliar spray. The Zn and MtEDTA were applied as a band 8 inches (20 cm) on both sides of nursery tree rows just as the buds that had been placed in the fall began growing in the spring. Some 20% of the trees died in groups of 10, 20, 30 or so and consecutively in the rows. The case is not yet settled. In the fourth case, many tomato transplants died when the transplanting was done with about 120 ml per plant of transplant solution containing besides N, P and K, about 19 mg Zn as ZnEDTA, 14 mg Mi as MnEDTA and 7 mg Fe as FeHEDTA. This case also is not yet settled. Cases such as these will probably discourage use of chelating agents in plant nutrition even if the chelating agents were not the damaging agent. Not enough developmental work was done on the potential toxicities from metal chelates. This trend to lawsuits makes it even more important to solve iron chlorosis problans via plant breeding.

Key words:

• Toxicities
• zinc
• chelates
• foliar sprays
• manganese