Herbicides plants

Exposure of humans and wildlife to arsenic may occur through air (emissions from smelters, coal-fired power plants, herbicide sprays), water (mine tailings runoff, smelter wastes, natural mineralization), and food (especially seafoods). 

Many of the Iowa farm s weed control experiments and whole farm experiences have confirmed the limitations of several nonchemical weed control practices. About 200A (80ha) of the farm followed a 5-year rotation of com-soybean-com-oat-hay. Corn following hay consistently produced the lowest returns due to consistently lower yields, which result from limited moisture and reduced potassium. In a 6-year rotation on 80A (32ha), with 3 years in a hay crop, Canada thistle became a problem at the end of the hay rotation and prior to com planting. Herbicides were occasionally applied to the Canada thistles in the hay fields. 

Uses pre-emergence or pre-plant herbicide used in many vegetable and field crops to control annual broadleaf weeds and grasses. 

Figure 3. Relationship between the number of moles of ethylene oxide in octylphenol (%), nonylphenol ( ), or laurylphenol ( J) polyoxyethylene glycol ether surfactant molecules and the toxicity index of these surfactants in mixtures with (a) paraquat, (b) dalapon, and (c) amitrole on corn plants. Herbicides applied at 1/64, 10, and 5 lb./ acre, respectively surfactant concentration was 0.005M in all cases. Toxicity index calculated by expressing fresh weight for each treatment as percentage of untreated control and subtracting this value from 100 (58)...

Herbicides have provided a more effective and economical means of weed control than mechanical cultivation. Together with fertilizers and improved varieties of plants, herbicides have made a immense contribution to increased yields and reduced costs. 

The U.S. Environmental Protection Agency reported extensively on its R and D programmes for detoxifying hazardous waste, e.g., from deserted refineries, chemical plants, herbicide and pesticide factories and storage facilities, etc. An interesting contribution was made by Col. D. Naugle, the Deputy Director of Environmental Policy, U.S. Department of Defense, which inevitably has to handle immense quantities of hazardous waste. The... 

Use Dormant ovicidal spray for fruit trees (highly phytotoxic and cannot be used successfully on actively growing plants), herbicide, insecticide. 

Interfering with protein function using specific inhibitors or antibodies. There are many protein inhibitors of metabolic enzymes that, when overexpressed, could have the potential to inhibit specific enzymatic steps (e.g., Ref. ). Nonprotein inhibitors of metabolic enzymes are also extensively used, resulting in some potent plant herbicides for which resistance can be easily manipulated, or in the formation of new compounds, when nonessential pathways are inhibited. ]... 

I Sinning, H Michel, P Mathis and AW Rutherford (1989) Terbutryn resistance in a purple bacterium can induce sensitivity toward plant herbicide DCMU. FEBS Lett 256 192-194... 

So far, the resistant biotypes obtained from other areas have all been of the highly-resistant (R) rather than I type (unpublished). Although all of the biotypes arose under the same situations (cotton monoculture and dinitroaniline herbicide as a pre-plant herbicide treatment) only the populations from two counties in South Carolina apparently have this lower level of resistance. As our case scenarios on other occurrences of dinitroaniline resistance increase, we may be able to relate this to certain sets of unique environmental conditions that may have allowed selection of one type of resistance phenotype over another. 

Plants synthesize all 20 common amino acids de novo. Glyphosate, a weed killer sold under the trade name Roundup, is an analog of phosphoenolpyruvate that specifically inhibits 3-enolpyruvylshikimate 5-phosphate synthase, a key enzyme of the pathway for chorismate biosynthesis. This compound is a very effective plant herbicide, but has virtually no effect on mammals. Why ... 

Few studies have been carried out on a large scale to investigate the environmental impact of GM plants. Herbicide-resistant oilseed rape plants have been evaluated mainly to assess the gene flows within species or to weed species closely related to oilseed rape [8, 9]. Regarding the pollinating entomofauna only two studies have been achieved recently. 

Another issue has been determination of proper doses and time points for sampling. The later the data are taken, the more genes unrelated to the primary target site are affected. With plants, an issue is whether to use whole plants or cell cultures. In whole plants, herbicides sometime target only cells of certain tissues, so that whole plant extaction of RNA dilutes the RNA of interest. Uniform and rapid uptake of the phytotoxin is also problematic with whole plants. 

Tissut M, Severin F. Plantes, herbicides et desherbage. ACTA, 1984 251. 

---