Foliar

Ref 15. Contact effect against adult mites. Eoliar residue bioassay. Table 3. Principal Agricultural Applications of Abamectin Foliar Spray ... 

Foliar Fungicides and Bactericides. Of the - 70,000 t/yr as copper in compounds used in agriculture, almost 75% is used in the control of fungi (see Fungicides, agricultural). The first reference to the use of copper as a fungicide dates to 1761 (83) where copper sulfate was used on wheat seed for the control of bunt. In 1807 (84) the discovery of copper as a fungicide was made and the discovery of Bourdeaux mixture (copper sulfate plus lime) followed in 1882. 

Composition of U.S. Forest-Type Groups by Foliar Terpene Emissions... 

When a forest system is subjected to acid deposition, the foliar canopy can initially provide some neutralizing capacity. If the quantity of acid components is too high, this limited neutralizing capacity is overcome. As the acid components reach the forest floor, the soil composition determines their impact. The soil composition may have sufficient buffering capacity to neutralize the acid components. However, alteration of soil pH can result in mobilization or leaching of important minerals in the soil. In some instances, trace metals such as Ca or Mg may be removed from the soil, altering the A1 tolerance for trees. 

Inhibitors must possess chemical and physical properties that will ensure absorption by root tips or penetration by foliar surfaces, and translocation to the active site. Once there they must assume the precise spatial configuration required to complement the molecular architecture of the active center if they are to block the key reaction. A comprehension of comparative biochemistry and information on how plants differ in the architecture of the reactive sites should assist in developing truly selective herbicides. 

Experimental exposure of several agricultural crops to ambient levels of acidic pollutants has not established measurable yield responses although foliar damage has been observed. Complex interactions with other airborne pollutants, particularly ozone, makes it difficult to exactly establish the damages that may be attributed to acidic deposition 14), It has not been possible to establish any critical level of acidic deposition in relation to crop damages. 

Garten, C.T., Jr. 1993 Variation in foliar abundance and the availability of soil nitrogen on Walker Branch watershed. Ecology 74 2098-2113. 

Cohen ML, SteinmetzWD. 1986. Foliar wash off of pesticides by rainfall. Environ Sci Technol 20 521-523. 

Next, we attempted to deal with translocation of foliar-applied TCDD. Labeled dioxins were applied to the center leaflet of the first trifoliate leaf of 3-week-old soybean plants and the first leaf blade of 12-day-old oat plants. All compounds were applied in an aqueous surfactant solution (Tween 80) to enhance leaf adsorption and to keep the water insoluble dioxins in solution. Plants were harvested 2, 7, 14, and 21 days after treatment, dissected into treated and untreated parts, and analyzed separately. Neither dioxin nor chlorophenol was translocated from the treated leaf. A rapid loss of the dichlorodioxin and dichlorophenol occurred from the leaf surface. This loss may have resulted from volatilization. Very little TCDD was lost from soybean leaves while a gradual loss (38% in 21 days) did occur from oat leaves. 

Several facts have emerged from our studies with 2,7-DCDD and 2,3,7,8-TCDD. They are not biosynthesized by condensation of chloro-phenols in soils, and they are not photoproducts of 2,4-dichlorophenol. They do not leach into the soil profile and consequently pose no threat to groundwater, and they are not taken up by plants from minute residues likely to occur in soils. Photodecomposition is insignificant on dry soil surfaces but is probably important in water. Dichlorodibenzo-p-dioxin is lost by volatilization, but TCDD is probably involatile. These compounds are not translocated within the plant from foliar application, and they are degraded in the soil. 

Chang, C.-S. and Giannasi, D. E. 1991. Foliar flavonoids of Acer sect. Palmata series Palmata. Syst. Bot. 16 225-241. 

Dodd, R. S., Eromard, E., Rafii, Z. A., and Blasco, F. 1995. Biodiversity among West African Rhizophora foliar wax chemistry. Biochem. Syst. Ecol. 23 859-868. 

Ahad JME, BS Foliar, EA Edwards, GF Slater, BE Sleep (2000) Carbon isotope fractionation during anaerobic biodegradation of toluene implications for intrinsic bioremediation. Environ Sci Technol 34 892-896. 

Elanson PJ, Lindberg SE, Tabberer TA, Owens JG, Kim KH. 1995. Foliar exchange of mercnry vapor evidence for a compensation point. Water Air Soil Pollut 80 373-382. 

Rea AW, Lindberg SE, Keeler GJ. 2001. Dry deposition and foliar leaching of mercury and selected trace elements in deciduous forest throughfall. Atmos Environ 35 1352-2310. 

Gawel JE, Trick CG, Morel FM. 2001. Phytochelatins are bioindicators of atmospheric metal exposure via direct foliar uptake in trees near Sudbury, Ontario, Canada. Environ Sci Technol 35 2108-2113. 

Pyraflufen-ethyl is also used as the defoliant for cotton and as a desiccant for potatoes. Pyraflufen-ethyl is a novel inhibitor of protoporphyrinogen IX oxidase. Inhibition of this enzyme in chloroplasts causes accumulation of protoporphyrinogen IX, which results in peroxidation of foliar cell membrane lipids under the light and finally death of cells. 

This herbicidal mode of action of pyraflufen-ethyl is similar to those of other peroxidizing herbicides containing a diphenyl ether moiety. Herbicidal effects of pyraflufen-ethyl are revealed as yellowing and browning in the foliar portion, and then death of the whole plant with leaf burn. 

For compounds applied to annual crops, another approach is to apply the compound to bare soil prior to crop emergence and follow the soil dissipation of the compound as the crop emerges and grows throughout its normal growing season.This is the appropriate use pattern for pre-emergence compounds and represents another approach that may used to study the soil dissipation of foliar-applied compounds. 

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