Host: burley tobacco (Nicotiana tabacum (burley type)
Description: Triazines are a group of herbicides which include atrazine, cyanazine, propazine, ametryn, prometryn, simazine, and metribuzin. Substituted ureas are a group of herbicides which include linuron, diuron, flometruron, and chloroxuron. Both triazines and urea produce similar symptoms. Injury may be caused foliar or root absorption. Low levels produce mild symptoms which first appear on the tips of the older leaves as a yellowing between the veins. As the degree of injury increases, the areas between the veins turn brown and progress toward the base of the leaf. The leaf will die back from the tips and the edges. Plants will be stunted, but may survive very low level exposure, however, plant death occurs from high level exposure. Foliar exposure can kill the plant, but at low levels, yellow to white areas are formed on the leaf which will turn brown and fall out. Ureas may produce a brighter yellow to white leaf mottling than the triazines. Symptoms of injury from herbicides in the triazine and ureas groups are similar and are difficult to separate.
Image type: Field
Image location: United States
Specimen in collection: No
Name: R.J. Reynolds Tobacco Company Slide Set
Organization: R.J. Reynolds Tobacco Company
Country: United States