Ferns, night shade, crotalaria, oleander, sicklepod, horse nettle, and many other plants that stay green in drought conditions have toxic components. Nitrate Poisonings . Drought and plant stresses are associated with increased nitrate levels in plants. Prevention is best achieved by controlling the type and quality of the forage offered. When in doubt, have it analyzed before feeding.
Nitrate poisoning is most serious after it rains.
Since nitrate levels are concentrated in the lower stalk, when it rains the nitrate is transported throughout the plant. Keep animals off these areas for at least one to two weeks after it rains. Protect from heat. When the sun is high in the sky, and the temperature and humidity begins to rise, keep a close eye on your cattle. Temperatures 80 and warmer, coupled with high humidity and sun light radiation cause problems.