Glyphosate Injury Symptom Expression in Citrus1

Citrus trees to which glyphosate (N-phosphonomethylglycine) was intentionally applied at 1.7, 3.3 and 6.6 kg/ha exhibited varying degrees of toxicity depending on tree age, location on tree sprayed, tissue maturity, and application rate. Symptoms included defoliation, twig dieback, malformed regrowth and callus inhibition around wound areas sprayed with glyphosate. While translocation from sprayed limbs was minimal, it was quite marked in citrus seedlings.