Presence and Persistence of Phytotoxic Substances in Wheat, Oat, Corn, and Sorghum Residues

Guenzi, W. D.; McCalla, T. M.; Norstadt, Fred A.

Presence and Persistence of Phytotoxic Substances in Wheat, Oat, Corn, and Sorghum Residues

1967

Guenzi, W. D. | McCalla, T. M. | Norstadt, Fred A.

Wheat, oat, corn, and sorghum residues, collected at time of harvest for each crop, contained water-soluble materials that were toxic to growth of wheat seedlings. The order of increasing toxicity was wheat, oat, corn, and sorghum residues.'To evaluate the potential toxicity of a residue, the state of decomposition must be considered. Wheat and oat residues essentially contained no water-soluble toxic components after 8 weeks of exposure to field environmental conditions. Corn and sorghum residues had considerably more toxic materials at harvest and required about 22 to 28 weeks of decomposition before the water-soluble portion of the residues was relatively nontoxic. Tests of nine wheat varieties showed that the toxicity of wheat straw water extracts to germination and growth of wheat seedlings differed among varieties.

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