Attempts to predict the extent of carryover and damage to sensitive crops the year following atrazine use have been only partially successful. The rate of atrazine disappearance and, therefore, the amount remaining the next year, is affected by soil texture, pH and organic matter content, as well as atrazine application rate and timing, rainfall, and plant growth the previous year. Chemical analyses for atrazine are complicated, expensive and can be made only in specialized laboratories. In addition, results obtained from chemical analyses do not necessarily reveal whether your crop will be injured. Plants Can Tell Atrazine injury on wheat.
Browning starts at the leaf tip and progresses toward the stem.
Biological assays, using test crops similar to the field crop to be grown, are practical and can be done with simple equipment found in most homes or offices. The biological assay outlined as follows does not provide an exact measure of the amount of atrazine present in the soil, but it can show you whether sufficient atrazine remains to harm sensitive crops. The Soil Sample Get a representative sample of soil from the field suspected of having atrazine residue. Take samples from the top two to three inches in several locations. Atrazine residue often occurs in patches in a field.