Fungicides and Herbicides

Herbicides, or weed killers, may be classified as pesticide chemicals. They can kill plants on contact, or they can be translocated (i.e absorbed by one part of the plant and carried to other parts where they exert their primary toxic effect). Most commonly used herbicides have a low toxicity and have caused few adverse effects in users. Some herbicides pose more serious problems to the central nervous system (CNS) and can cause depression. The skin absorption of herbicides also may cause skin irritation, dermatitis, and photosensitization in addition to peripheral motor neuropathies. 

Fluchloralin Isopropalin, Nitralin, Oryzalin, Penoxylin, Profluralin, Trifluralin 

Phenoxy aliphatic acids 2,4-D, 2,4-DB, 2,4,5-T, Dichlorprop, MCPA, MCPB, Mecoprop, Silvex 

Substituted ureas Chloroxuron, Diuron, Fenuron, Linuron Metobromuron, Monuron, Norea 

Thiocarbamates Butylate, Cycloate, Diallate, EPTC, Molinate, Pebulate, Trillate, Vemolate 

---

W. J. Hayes, Jr., and E. R. Laws, Jr., eds.. Handbook of Pesticide Toxicology, Academic Press, Inc., San Diego, Calif., 1990. Three volume set provides detailed toxicological profiles of more than 250 insecticides, herbicides, and fungicides each compound described by identity, properties, and uses toxicity to humans, laboratory animals, domestic animals, and wildlife includes comprehensive coverage of diagnosis, treatment, prevention of injury, effects on domestic animals, wildlife, and humans - ISjOOO references. 

In addition to conventional pesticides such as insecticides, herbicides, and fungicides, there are other chemicals classified as pesticides and regulated under FIFRA. These chemicals include wood preservatives, disinfectants (excluding chlorine), and sulfur. In the United States these chemicals have aimual usage of about 500,000 t, which is equal to conventional pesticides. 

Arsonic and arsinic acids have found a number of industrial uses. They have been used as corrosion inhibitors for iron and steel, additives to motor fuel, agricultural bactericides, herbicides, and fungicides. 3-Nitro-4-hydroxyphenylarsonic acid (roxarsone) [121 -19-7] C H AsNOg, has found widespread use as an additive to poultry feed for the control of coccidiosis and other poultry diseases (122,123). Arsanilic acid [98-50-0] C HgAsNO, has also been used for this purpose (124) and for growth promotion in swine. It is manufactured and suppHed by Duphar Nutrition Co., Inc., Fleming Laboratories, Inc., Dr. Mayfield Laboratories, Inc., and Whitmoyer Laboratories, Inc. 4-Nitrophenylarsonic acid [98-72-6] C H AsNO and... 

Hassall, K.A. (1990). A readable student text, particularly useful for the metabolism and mode of action of herbicides and fungicides. 

Pesticides, including insecticides, herbicides, and fungicides, are widely used in agriculture, and the potential for these residues to accumulate in food has led to concern for human safety. Pesticide residues may enter food animals from environmental sources or from treated or contaminated feeds. Immunoassay development for pesticides has had major impacts for pesticide registrations, analysis of residues in foods, monitoring environmental contamination, determination of occupational exposure, and integration of pest management. 

Used industrially for the manufacture of flavorings, perfumes, acrolein, diallyl phthalate, diallyl isophthalate, and pharmaceuticals used to denature alcohol. Used agriculturally as herbicide and fungicide. 

A series of benzoxazolo[3,2-r][l,2,4]triazoles have been synthesized and submitted to herbicidal and fungicidal testing < 1997IJC(B)711 >, the most active being compound 385 (Figure 25) in both analyses. 

IAEA-FAO-UNEP (1991) MEDPOL workshop on the assessment of pollution by herbicides and fungicides. Monaco, p 362... 

Strong acids include battery acid, murintic acid, and hydrochloric acid. Weak acids include acetic acid, toilet bowl cleaner, and lactic acid. Banned pesticides include Silvex, Mirex, Aldrin, Chlordane, DDT, and Heptachlor. Caustics include oven cleaner and drain cleaner. Flammables include alcohol, acetone, turpentine, lacquer, and paint thinner. Pesticides include rodent poisons, insecticides, weed killer, and other herbicides and fungicides. Pesticide containers should be triple-rinsed, and the contents sprayed on crops or yard, before discarding. 

Dearden, J.C. Townend, M.A., in "Herbicides and Fungicides, Factors Affecting their Activity", McParlane, N.R., Ed. Special Publication No. 29, Chemical Society London, 1977. 

Unsaturated 5(477)-oxazolones have been studied as ultraviolet (UV)-absorbing layers," " as fungicides," " and as antibacterial agents." " " For example, 4-(3-phenoxybenzylidene)-2-substituted-5(4r/)-oxazolones 358 have been prepared and used as herbicides and fungicides." " ... 

Dimethy la mine and Derivatives Dimethylamine, (H3C)2NH, mw 45.08, N 31.07%. col gas at RT and liq at below 7°, sp gr 0.680 at 0°/4, fr p —92.2° extremely flammable and hazardous causes bums sol in w, ale eth. Can be prepd by passing a mixture of ammonia with vapors of methanol over a catalyst, such as silica gel. Has been used in agricultural herbicides and fungicides, synthetic textiles, fiber solvents, rubber vulcanizing accelerators and in missile fuels (Refs 1, 2, 4)... 

In their studies the enzyme activity decreased when reagents were added that complex with thiols hence it was concluded that cysteine was probably the key enzymatic nucleophile. The production of this enzyme could be induced by exposure of the bacteria to various phenylamide- or phenylurea-containing herbicides and fungicides. The enzyme was also capable of hydrolyzing a variety of other phenylamides and phenylureas, albeit at somewhat different rates. 

Englehardt, G., P. R. Wallnofer, and R. Plapp, Purification and properties of an aryl acylamidase of Bacillus sphaericus, catalyzing the hydrolysis of various phenylamide herbicides and fungicides , Appl. Microbiol., 26,709-718 (1973). 

Among the abiotic factors most widely used to manipulate and vary the metabolism of phenolics, are biocides, primarily herbicides and fungicides, and different nutrients. 

JF Lawrence. Confirmation of some organonitrogen herbicides and fungicides by chemical derivatization and gas chromatography. J Agric Food Chem 24 1236-1238, 1976. 

The agricultural use of pesticides such as insecticides, herbicides, and fungicides has clearly reduced crop losses due to insects, weeds, and plant diseases in the US and throughout the world. The benefits from agricultural pesticides include improved crop yields, greater availability of fruits, vegetables, and grains, and lower consumer costs (Ecobichon, 1996). 

---