Carbofuran treatment

On the basis of evidence presented herein, this author conservatively estimates that, in terms of total carbofuran in water, damage is possible to aquatic invertebrates at >2.5 pg/L and to teleosts at >15 pg/L. These levels could be attained during a heavy rainfall shortly after carbofuran treatment of adjacent fields. Among sensitive species of warm-blooded animals, dietary concentrations as low as 10 pg/kg ration have demonstrable effects, which were measurable only after extended periods postingestion. For comparison, this level is about 1/5 that allowed in meat by-products for... 

Factors Affectino the Activity of Soil Microbial Populations Enhanced bv Carbofuran Treatment... 

The effect of additional 10 ppm carbofuran treatments made at monthly intervals on the E-factors observed for a sandy loam soil collected from the same location in three consecutive years are shown... 

The results of a study of carbofuran treatment intensity on the cross enhancement factors for carbaryl, cloethocarb and oxamyl are... 

Of the three insecticides studied, enhanced biodegradation has been definitively associated with repeated applications of carbofuran ( ). In our studies, the chemical assay data from 1987 only weakly suggested the development of enhanced biodegradation, and the data from 1988 indicated that biodegradation rate was not affected by multi-year carbofuran treatments. Since a severe drought occurred in 1988, a lack of soil moisture may have slowed the rate of carbofuran degradation. 

Pharmacologically, carbofuran inhibits cholinesterase, resulting in stimulation of the central, parasympathetic, and somatic motor systems. Sensitive biochemical tests have been developed to measure cholinesterase inhibition in avian and mammalian brain and plasma samples and are useful in the forensic assessment of carbamate exposure in human and wildlife pesticide incidents (Bal-lantyne and Marrs Hunt and Hooper 1993). Acute toxic clinical effects resulting from carbofuran exposure in animals and humans appear to be completely reversible and have been successfully treated with atropine sulfate. However, treatment should occur as soon as possible after exposure because acute carbofuran toxicosis can be fatal younger age groups of various species are more susceptible than adults (Finlayson et al. 1979). Carbofuran labels indicate that application is forbidden to streams, lakes, or ponds. In addition, manufacturers have stated that carbofuran is poisonous if swallowed, inhaled, or absorbed through the skin. Users are cautioned not to breathe carbofuran dust, fumes, or spray mist and treated areas should be avoided for at least 2 days (Anonymous 1971). Three points are emphasized at this juncture. First, some carbofuran degradation... 

Prior treatment with carbofuran produced rapid degradation attributed to acclimatized soil bacteria (Felsot et al. 1981)... 

Evidence was obtained recently that pesticide vapors may enter the air by still another mechanism, involving plant circulation and water loss (57). Rice plants were found to efficiently transport root-zone applied systemic carbamate insecticides via xylem flow to the leaves, eventually to the leaf surface by the processes of guttation and/or stomatal transpiration, and finally to the air by surface volatilization. Results from a model chamber showed that 4.2, 5.8, and 5.7% of the residues of carbaryl, carbofuran, and aldicarb, respectively, present in rice plants after root soaking vaporized within 10 days after treatment. The major process was evaporation of surface residues deposited by guttation fluid. 

Measureable air concentrations of parent carbofuran were present from both systemic treatments (Figure 10). The root soak treatment gave a maximum vapor concentration 1 day after treatment (i. e., transplanting), and then a slow decrease thereafter. This is because the root soaking is essentially a one-shot treatment and evaporation from the leaf surface is apparently the slow step in the distribution/loss process. By contrast, the gelatin capsule treatment boosted air concentrations continually over the period of sampling. This arises through an apparently continual supply of insecticide to the... 

Figure 10. Carbofuran residue in high volume air samples taken above rice paddies treated by root soaking seedlings (O) or by root soaking followed by gelatin capsule root zone treatment (51) (DAT = days after treatment each point = 8 hr of sampling at 623 L/min)...

In early and standard treatments and of carbofuran all produced greater bee mortality than did MMP.(1 )... 

To increase the marketability of Collego, its compatibility with chemical pesticides has been investigated. Mixtures of CGA with propanil [N-(3,4-dichlorophenyl)propanamide], molinate [S-ethyl hexahydro-lH-azepine-l-carbothioate], 2,4,5-T, and benomyl [methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate] were detrimental to CGA s efficacy (31). If, however, propanil, 2,4,5-T, fentin hydroxide (triphenyltin hydroxide), pencycuron N-[(4-chlorophenyl)methyl]-N-cyclopentyl-N -phenylurea), each at 0.56 kg ai/ha, and SN-84364 [3 -isopropoxy-2-(trifluoromethyl) benzanilide] (at 0.40 kg ai/ha) were applied after CGA treatment, disease and development were not inhibited (32). The herbicides, acifluorfen 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid) (0.56 kg ai/ha) and bentazon [3-(1-methylethyl)-(IH)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] (0.56 to 1.1 kg ai/ha), or the insecticides, malathion [diethyl(dimethoxyphosphinothioylthio)succinate] (0.56 kg ai/ha) and carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate), (0.56 kg ai/ha) could be applied with CGA from a single tank mixture (33-34). ... 

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