Grass weed

Aliphatic-Garboxylics. There are only two herbicides present in this class, trichloroacetate [76-03-9] (TCA) and dalapon [75-99-0]. These are used primarily for the selective control of annual and perennial grass weeds in cropland and noncropland (2,299). Dalapon is also used as a selective aquatic herbicide (427). Dalapon and TCA are acidic in nature and are not strongly sorbed by sods. They are reported to be rapidly degraded in both sod and water by microbial processes (2,427). However, the breakdown of TCA occurs very slowly when incubated at 14—15°C in acidic sods (428). Timing not only accelerates this degradation but also increases the numbers of TCA-degrading bacteria. An HA has been issued for dalapon, but not TCA (269). 

Grass weeds pose a risk for infections with C. purpurea. 

Marijuana (reefer, pot, grass, weed) is the most commonly used illicit drug. The principal psychoactive component is A9-tetrahydrocannabinol (THC). Hashish, the dried resin of the top of the plant, is more potent than the plant itself. Pharmacologic effects begin immediately and last 1 to 3 hours. 

Molinate (S-ethyl hexahydro-azepine-l-carbothioate) has been widely used for broadleaf and grass weed control in rice culture. The 96-hour LC50 of technical molinate in the common goldfish is 30 ppm (1) and the medium tolerance limits (LTm) for molinate in mosquito fish (Gambusia affinis) are 16.4 ppm for 96 hours (J2). Kawatsu (3) estimated the 20-day lethal concentration of molinate in Japanese carp (Cyprinus carpio) var. Yamato koi at 0.18 ppm. However, there was no toxic effect of molinate on American carp at concentrations of 10 ppm during a two-week observation (40. ... 

Lawn people how grasses, weeds, and chemicals make us who we are / Paul Frederick Robbins, p. cm. 

While I would direct any serious student of the lawn (or of vernacular culture more generally) to these excellent works, this book begins where they leave off While I draw heavily on the insights of these previous explorations, the volume diverges in its emphasis on explaining the work the lawn does on us as individuals, communities, and cities. The book also adopts an approach that focuses especially on broader political economy, since while the lawn is of course a fundamental product of American imagination-a symbol—it is also a vast and coercive economy. More specifically, monocultural lawn cultivation imposes a set of economic relationships between grasses, weeds, chemicals, companies, and people. 

Propanil Anilide 709-98-8 0.42 1961 Herbicide A postemergence herbicide used for broad-leaved and annual grass weed control in rice and other crops... 

The N-arylalanine ester herbicides such as benzoylprop-ethyl and flam-prop-methyl and difenzoquat (Figure 2.26) prevent cell elongation in certain grass weeds, allowing the crop to overtop them. The weeds are thus outcompeted and die. The exact mode of action is not certain but it is proposed that these compounds interfere with the site of action of the auxins. 

Aliphatic-Carboxylics. These are used primarily lor the selective control of annual and perennial grass weeds in cropland and noncropland. Dalapon is also used as a seleclive aquatic herbicides. 

On the other hand, the broad weed control spectrum of chloramben, which was introduced in 1959, brought with it widespread acceptance. As an over-the-row band for control of both broadleaf and grass weeds, cost was minimized. With good crop tolerance, chloramben dominated the early soybean herbicide market. During 1972, 85% of the product was applied as the granular formulation (Table 4.2). However, as application practices changed for the soybean crop, banded applications became an inconvenience. Herbicides such as metribuzin (a triazine herbicide), linuron, and bentazon, which could be applied as an affordable broadcast treatment, soon became products of choice, and the marketing of chloramben was eventually discontinued in 1990. 

The triazines played a significant role in the transformation of agriculture in the latter half of the 20th century - in Europe and around the world. Terbutryn was extensively used at one time for grass weed control in winter cereals. Terbuthylazine has played a major role in com and in weed control of peas and other broadleaved legume crops. Simazine has been used on a large scale for weed control in crops. 

Chlorotriazines are widely used for preemergence and postemergence control of many broadleaf and grass weeds in com, sorghum, sugarcane, and a variety of other crops. Methylthiotriazines are used for preemergence and post-directed... 

Weimer, M.R., B.A. Swisher, and K.P. Vogel (1988). Metabolism as a basis for differential atrazine tolerance in warm-season forage grasses. Weed Sci., 36 436 -40. 

Table 10.1(b) Earliest discovery of biotypes of 21 triazine-resistanti monocotyledonous (grass) weeds 3... 

In some triazine-resistant species where resistance is due to more rapid metabolism of the herbicide, the weeds develop resistance gradually and may be only slightly resistant. This is especially true with some of the monocot or grass weeds that are already partially inherently resistant to atrazine (Thompson et al. 1971 Gressel et al., 1982, 1983). DePrado et al. (1995) found that fall panicum has the capacity for rapid detoxification, which is slightly greater in plants from fields that have been repeatedly treated with atrazine. 

Cardina, J., D.H. Sparrow, and E.L. McCoy (1996). Spatial relationships between seedbank and seedling populations of common lamb-squarters (Chenopodium album) and annual grasses. Weed Sci., 44 298-308. 

Broad-spectrum weed control Atrazine and simazine control a broad spectrum of broadleaf and grass weeds. In fact, of the 28 weeds species considered in the analysis, atrazine provides a higher level of control of a greater number of them than any other herbicide. 

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