Agriculture Reference
In-Depth Information
q.
Pyridazinones
Most members of this group are used as preemergent and early postemer-
gent, broad spectrum herbicides. Since the mode of action of this group is
varied and complex, effecting many biosynthetic processes that are involved in
the photosynthetic pathway, there is no single easily identifiable mode of ac-
tion. The results of their activities is an inhibition in chlorophyll synthesis
and a bleaching of the foliage.
Several members of this group are formulated as emulsifiable concen-
traters with solvents which can cause severe to moderate injury to the eyes,
skin, and respiratory tract.
Table 5.22
Commercial products containing pyridazinone compounds.
Active Ingredient
Trade Names
Clomazone
Command, Gamit, Merit
Pyrazon (Chloridazon)
Pyramin
Norflurazon
Evital, Solicam, Zorial Rapid 80
Oxadiazon
Chipco, Ronstar
r.
Phthalic Acid Herbicides
There are only two significant compounds in this group, and these are en-
dothall and chlorothal (DCPA). Chlorothal is a selective, preemergent herbi-
cide used to control many annual grasses and broadleaf weeds. Endothall has
several different uses such as a preemergent and postemergent herbicide, a defo-
liant, desiccant, aquatic algicide, and growth regulator.
Toxicity
Chlorothal is sligh tly irrit ating to the eyes, while endot hall has a
“Warning” classification because of its moderate oral toxicity.
Mode of Action
Endothall has been shown to interfere with photosynthesis, while
chlorothal inhibits cell division in the meristemic tissue.
Table 5.23
Commercial products containing phthalic acid herbicides.
Active Ingredient
Trade Name
Chlorothal
Dacthal
Endothall
Accelerate, Aquathol K, Des-I-Cate, Endothal
Turf herbicide, Herbicide 273, Hydrothol
s.
Pyridinoxy and Picolinic Acids
This group of herbicides consists of clopyralid, fluroxypr, picloram, and
triclopyr. These compounds have both soil absorption and foliar activity.
