Agriculture Reference
In-Depth Information
Mode of Action
Triazines act by interfering with photosynthesis and it seems clear that,
like the substituted urea herbicides, the primary site of action is inhibition of
the Hill reaction of photosynthetic electron transport.
Toxicity
The triazines listed below are nonirritating to mildly irritating to eyes or
skin. Cyanazine has a designation of Toxicity Category II, “Warning” be-
cause of its oral LD
50
.
Table 5.25
Commercial products containing triazines.
Active Ingredient
Trade Names
Ametryn
Evik, Gesapax
Atrazine
AAtrex, Atratol 90, Atrazine,
Aziprotryne
Brasoran, Mesoranil
Cyanazine
Bladex, Fortrol
Dipropetryn
Sancap
Ethiozin
Tycor
Metamitron
Goltix
Metribuzin
Lexone, Sencor, Sencoral
Prometryne
Caparol
Simazine
Aquazine, Caliber 90, Princep
Terbuthylazine
Gardoprim
Terbutryn
Ternit
u.
Uracils and Substituted Uracils (Pyrimidines)
Unsubstituted uracils have no herbicidal activity but certain derivatives
substituted in the 3,5,6-positions are active. The most important examples
are bromouracil, terbacil, and lenacil. These compounds were introduced by
DuPont in 1963. These herbicides are applied to the soil and are used for se-
lective weed control. Bromacil and terbacil are pre- and postemergence herbi-
cides; they control a wide spectrum of grass and broadleaf weeds when applied
early in the growing season. These compounds must be carried to the roots
by soil moisture, where they are absorbed and translocated to the rest of the
plant. This family of herbicides is used for asparagus, sugar cane, pineapple,
apple, and citrus crops.
Mode of Action
Uracils and substituted uracils owe their herbicidal activity to inhibition
of photosynthesis by blocking the Hill reaction. This activity also present in
the ureas and triazines.
Toxicity
Liquid formulations of bromacil are designated to Toxicity Category II be-
cause they can irritate the nose, throat, and skin if inhaled as mist or dust.
