Defoliant

Dioxin IS carried along when 2 4 5 trichlorophe nol IS converted to 2 4 5 T and enters the environ ment when 2 4 5 T is sprayed on vegetation Typically the amount of dioxin present in 24 5 T is very small Agent Orange a 24 5 T based defoliant used on a large scale in the Vietnam War contained about 2 ppm of dioxin... 

CaNCN is used as a direct application fertilizer, weed killer, and cotton defoliant it is also used for producing cyanamide, dicyandiamide and melamine plastics. Production formerly exceeded 1.3 million tonnes pa, but this has fallen considerably in the last few years, particularly in the USA where the use of CaNCN as a nitrogenous fertilizer has been replaced by other materials. In 1990 most of the world s supply was made in Japan, Gennany and Canada. 

One of the economically most important areas in the control of plant processes is defoliation—the intentional removal of leaves. Large quantities of several chemicals currently are employed for this purpose, including magnesium chlorate and DEF (S,SyS-tributyl phosphor otrithioate), and the principal commercial value is for defoliation of cotton. Several synthetics such as 4-chlorophenoxyacetic acid and naphthalene-1-acetic acid are used to provide the opposite but related effect of retarding or limiting fruit drop in apples, stone fruits, and grapes. 

Surveys of Sugar Maple decline have been conducted in both Quebec and in Ontario. If these declines continue over the long term, the damages will undoubtedly become dramatic and serious. In a survey in Quebec between 1985 and 1987, of over 2 million hectares of stands, 47% exhibited light decline symptoms (11 to 25% defoliation), 3% showed severe decline (25% defoliation), while the remaining 50% revealed only marginal symptoms (10% defoliation). In Ontario, surveys have found that the highest decline occurs across the... 

The least hardy fruit producers showed marked reductions in fruit production and significant leaf losses. In addition up to 20% of the trees were killed outright by the frost. The susceptible populations were either killed outright (up to 82%) or failed to produce any fruit crops and were generally defoliated. 

Caemmerer, S. von Farquhar, G.D. (1984). Effects of partial defoliation, changes of irradiance during growth, short-term water stress and growth at enhanced p(C02) on the photosynthetic capacity of leaves of Phaseolus vulgaris L. Planta, 160, 320-9. 

Concerning anthropogenic sources, methyl arsenic compounds such as methyl arsonic acid and dimethylarsinic acid have been used as herbicides, and were once a significant source of environmental residues. Dimethyl-arsinic acid (Agent Blue) was used as a defoliant during the Vietnam War. 

At Eglin AFB, Florida, the U.S. Air Force initiated an experiment in 1962 to test aerial application equipment for deposition of defoliants... 

Continuous labeling—laboratory Defoliation N levels shading Green panic (Panicum mcmmum) 56... 

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. 

Universal waste pesticide Pesticide means any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest, or intended for use as a plant regulator, defoliant, or desiccant. 

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