Broadleaf weed control

Table VII. Mean broadleaf weed control of mulched and unmulched treatments averaged over location, crop, and weed species...

Dicamba was not detected in Lake Superior in 1996 and 1997. Its concentration in each of the lakes decreased in the order Lake Huron/Georgian Bay > Erie > Ontario > Superior. Dicamba, like 2,4-D, may also be applied in urban areas several times from spring through fall for broadleaf weed control. 

The next major crop use in the United States added to the Atrazine 80W label was weed control in sugarcane, approved by the USDA June 6, 1961. The 80 W formulation soon became the broadleaf weed control product of choice for sugarcane and remained so for many years until improved formulations of atrazine were developed. 

Dipropetryn. Dipropetryn was first developed for specific broadleaf weed control in cotton grown on sandy soils in the southwest United States, particularly Texas. It was sold in the early 1970s under the trade name Sancap and used outside the United States under the trade name Cotofor in cotton and watermelon. 

After World War II, mechanization became virtually essential for weed control and resulted in dramatic adoption of tractors in sugarcane. In Louisiana, the number of tractors on sugarcane farms doubled between 1940 and 1947. During this same period, sugarcane acreage in Louisiana increased 20% while farm labor decreased 40%. Much of this change was due to cultivation with tractors and the introduction of 2,4-D for broadleaf weed control (Conrad and Lucas, 1995). 

Simazine has been widely used in raspberry, boysenberry, and blueberry production (Welker and Brogdon, 1968). When used alone, broadleaf weed control has been excellent, but annual grasses and perennial weeds were not controlled in blueberry (Hertz and Wildung, 1978). Spring-planted raspberry crops do not tolerate weed competition well (Lawson and Wiseman, 1976). Simazine and diuron have been used extensively in many states in new or established cane-planted raspberry. 

Chandran, R.S., J.F. Derr, and S.W. Bingham (1998). Effect of isoxaben application rate and timing on residual broadleaf weed control in turf. Weed Technol., 12 569-574. 

Warren, L.S., T.W. Gannon, and F.H. Yelverton (2005). Efficacy of recently registered sulfonylurea herbicides for broadleaf weed control in warm season turf. Proc. South. Weed Sci. Soc., 58 115. 

Typically, the inclusion of atrazine in an herbicide program results in good-to-excellent control of broadleaf and grass weed species. In a summary of 750 Midwest research trials conducted from 1972 through 1991, control efficacy was 80-100% in 74% of the broadleaf weed control trials in which atrazine was used (Pike et al., 1994). When atrazine was not used and other herbicides were used, broadleaf control in the 80-100% range was obtained only 54% of the time. 

Uses Paraquat is a colorless, odorless, white or pale yellow crystalline solid that is hygroscopic. Paraquat is a quaternary nitrogen herbicide that is widely used for broadleaf weed control. It is a quick-acting, nonselective compound that destroys green plant tissue on contact and by translocation within the plant. It has been employed for killing marijuana in the United States and Mexico. It also is used as a crop desiccant and defoliant, as well as an aquatic herbicide. Paraquat is highly persistent in the soil environment, with a reported field half-life of greater than 1,000 days.5-7,17... 

EPTC was repositioned in the marketplace as an annual grass herbicide in 1985, a rotational statement was added to prevent the repeated annual use of EPTC, and shattercane control claims were removed from the label. EPTC was targeted specifically for foxtail (Setaria spp.) and annual broadleaf weed control in the north where cool and wet soils prevail in the spring. EPTC has been a very successful product, provided excellent weed control, and increased in market share every year since its reintroduction as an annual grass and broadleaf herbicide. The other commercial carbamothioate herbicides, EPTC + dietholate and butylate, were positioned as difficult to control weed and southern corn belt herbicides, respectively. No rotational statements have been added to the EPTC + dietholate and butylate labels. 

Synthetic studies focused on the bicyclic heterocycle led to the discovery of a new sub-class of sulfonamides where the triazolo[l,5-a]pyrimidine ring was replaced with a triazolo[l,5-c]pyrimidine ring. Further investigations led to the development of diclosulam (3) and cloransulam-methyl (4) for broadleaf weed control in soybeans, and florasulam (5) for broadleaf weed control in cereals. To fully explore this sub-class of sulfonamides, an investigation was initiated to determine if reversing the sulfonamide linkage (6) would lead to compounds with the spectrum of activity on weeds and crop selectivity different from 3, 4, and 5. 

Cloransulam-methyl and diclosulam are members of the triazolo[ 1,5-c] pyrimidine sulfonanilide family of AHAS-inhibiting herbicides. Both compounds show excellent crop selectivity, broad-spectrum broadleaf weed control and low toxicity. The herbicidal utility of cloransulam-methyl in soybeans was first presented in 1994 [6, 7] and further described in 1995 [8, 9] and 1996 [10-12]. Diclosulam was first described for use in soybeans and peanuts in 1997 [13] with additional description in 1998 [14] and 1999 [15-17]. 

Topramezone is aimed at the post-emergence control of major grass and broad-leaf weeds in corn crops worldwide. This means that this new corn compound differentiates itself from sulcotrione and mesotrione in that it shows real cross spectrum activity like isoxaflutole and it is not limited to mainly broadleaf weed control. 

Florasulam (II) is a triazolopyrimidine herbicide used for selective broadleaf weed control in wheat, barley, and oats, but is included in this experiment as a positive standard because it is rapidly metabolized in the test system. Azoxystrobin (12) serves as a negative standard because it metabolizes slowly in the test system. These standards provided positive and negative controls for the system, and helped put the metabolism rates of the other compounds into perspective. 

Annual Broadleaf Weed Control in No-Till Systems... 

IC-22 showed much higher herbicidal activity than that of those repoted plant PDHc inhibitors, acylphosphinates and acylphosphonates[l, 27]. Those compounds exhibited 80-100 % inhibition against weeds at 2.8 kg/ha but at this rate they had shown unacceptable phytotoxicity to the crops. Compared with acylphosphinates and acylphosphonates, IC-22 exhibited promising herbicidal activity and selectivity for development as a selective post-emergence herbicide which may be used for broadleaf weed control in monocot crop fields. 

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