Agriculture Reference
In-Depth Information
than those likely absorbed in the course of occupational exposure. Thiabenda-
zole is rapidly metabolized and excreted in the urine, mostly as a conjugated
hydroxy-metabolite. Symptoms and signs that sometimes follow ingestion
are dizziness, nausea, vomiting, diarrhea, epigastric distress, lethargy, fever,
flushing, chills, rash and local edema, headache, tinnitus, paresthesia, and hy-
potension.
Most formulations of benomyl are classified as Toxicity Category IV and
are considered relatively nontoxic. Arbotect, a trade name of a product con-
taining thiabendazol, is classified as Toxicity Categrory III and is considered a
slight eye and skin irritant. Fuberidazol is classified as a Toxicity Category II
fungicide.
Table 5.35
Commercial products containing benzimidazole fungicides.
Active Ingredients
Trade Names
Benomyl
Benlate, Tersan, Benex
Thiabendazole
Apl-Luster, Arbotect, Mertect, TBZ, Tecto, Thibenzole
Carbendazim
Bavistin, Delsene
Fuberidazol
Fuberidazole
c.
Pyrimidine Compounds
In the late 1960s, the pyrimidines were introduced as fungicides. This
group includes dimethirimol, ethirimol, bupirimate, and fenarimol. They are
used to control powdery mildew in several plants.
Mode of Action
As with almost all systemic fungicides, after foliar or soil application,
absorption and translocation via the xylem follows. The mechanisms of ac-
tion of pyrimidines are not very clear, however, information suggests that
spore germination and mycelial growth are inhibited. In addition, studies with
ethirimol suggest that it inhibits RNA synthesis as well as adenosine metabo-
lism by blocking adenosine deaminase.
Toxicity
Most of the pyrimidines are classified in Toxicity Category III and are
only slightly irritating. However, several pyrimidine formulations (e.g., Ru-
bigan) are in Category II. In general, it is the properties of the inert ingredi-
ents present in the formulations that increase the toxicity product.
Table 5.36
Commercial products containing pyrimidines.
Active Ingredients
Trade Names
Dimethirimol
Milcurb
Ethirimol
Ethirimol, Milcurb Super
