Herbicides change

Discovery. The traditional approach to new pesticide discovery was to make iatuitive changes ia the substitueats oa a promising primary chemical stmcture. Initially, materials from any source were subjected to screening for biological activity as iasecticides, herbicides, or fungicides. 

The chlorobenzene operations in the United States were developed primarily for the manufacture of phenol, aniline, and DDT. However, with the process changes in the production of phenol and aniline, the phase-out of DDT production, and changes in the herbicide and solvent markets, the U.S. production of chlorinated benzenes has shmnk by more than 50% since the total production peaked in 1969. U.S. production of monochlorobenzene peaked in the 1960s and decreased to a low of 101 million kg in 1986 with an 11% and 9% increase, respectively, in 1988 and 1989. 

The commercial exploitation of our increased understanding of protein stmcture will not, of course, be restricted to the pharmaceutical industry. The industrial use of enzymes in the chemical industry, the development of new and more specific pesticides and herbicides, the modification of enzymes in order to change the composition of plant oils and plant carbohydrates are all examples of other commercial developments that depend, in part, on understanding the structure of particular proteins at high resolution. 

Dalapon 0.2 0.2 Minor kidney changes Runoff from herbicide used on rights of way... 

Since 1945 the use of synthetic pesticides in the United States has grown 33-fold. The amounts of herbicides, insecticides, and fungicides used have changed with time due, in large part, to changes in agricultural practices and cosmetic standards (14, 15). At the same time, the toxicity and biological effectiveness of these pesticides have increased at least 10-fold (15). For example, in 1945 DDT was applied at a rate of about 2 kg/ha. With the more potent insecticides available now, similar effective insect control is achieved with pyrethroids and aldicarb applied at 0.1 kg/ha and 0.05 kg/ha, respectively. 

Chemical manipulation of phenolic allelochemical production in plants has two potential values 1) for study of the role of phenolic allelochemicals in plant interactions with other organisms and 2) to alter such interactions for agricultural purposes. The first of these uses has already been accomplished on a limited scale (21, 22, 50, 51, 84, 86), however, there is no published evidence of the latter. This does not mean that herbicide and growth regulator-influences on plant secondary metabolism do not affect agricultural ecosystems by changing allelochemic compositions of plants. It is likely that this is the case, but it... 

Most dynamic factors that affect fruit quality are agronomic practices that can be changed by farmers over relatively short time spans. They are mainly related to fertility management and crop protection and other husbandry interventions and inputs such as pesticides, fertilisers, herbicides, thinning agents and so on. The permitted tools for these activities, however, differ greatly between conventional and organic fruit production. The consequences... 

I always ask myself Okay, what am I learning from this experience I don t think we can go through life without learning from our negative experiences. Prior to my chemical sensitivity I used pesticides, herbicides, synthetics and all of that. I ve learned so much in the past fifteen years about my body, the universe and ecology. I ve changed so much in my viewpoint on life and my way of inter-... 

Many changes are occurring in the cultivation of tropical crops, and it is difficult to make any predictions in a field which is undergoing rapid changes. However, the present trend in the use of herbicides appears to be away from the use of single chemicals. Usually the combination of chemicals involves 2,4-D with some other herbicide, although TCA combined with a contact herbicide has been widely used. Some of the newer chemicals, such as TCA and CMU, will probably be used more in the future, especially if the cost can be reduced. 

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