Sodium thiosulfate, alone, is also an effective antidotal therapy for prussic acid poisoning. Forages Prussic acid poisoning is most often associated with sorghums and sudangrass. However, a number of other plants can be cyanogenic. Young, upper leaves have more prussic acid than lower leaves. New shoots often contain high concentrations of prussic acid.
New shoots produced after frost can be especially hazardous.
Prussic acid content appears to be higher in plants grown in soils high in nitrogen and low in phosphorus. When fertilizing forage ground, use split nitrogen applications when the total amount exceeds 60 lbs of N per acre to decrease the risk of prussic acid toxicity. Herbicides, such as 2,4-D, can increase prussic acid concentrations in forage for several weeks after application. Plan grazing rotations accordingly. Drought increases the chance for high levels of prussic acid in plants.