Broadleaf weed

Phenoxyalkanoics. The phenoxyalkanoic herbicide grouping is composed of two subgroups, the phenoxyacetic acids and the phenoxypropionic acids. The phenoxyacetic acid herbicides include some of the first commercially successhil herbicides, eg, 2,4-D. They continue to be widely used for foUar control of broadleaf weeds. The more heavily functionalized phenoxypropionic acid herbicides are relatively new herbicides compared to the phenoxyacetic acids and are used primarily for selective control of grassy weeds in broadleaf crops (2,296,297). 

Several 7-substituted (H, halogen, alkoxy, alkylthio, halogen, alkyl, carboxyl) oxazolo[5,4-/i]quinolines were found to be very effective against broadleaf weeds (90EUP1, 90GEP1). 

Chloroacetanilides are soil-applied herbicides used for pre- and early post-emergence control of annual grasses and broadleaf weeds in crops. Representative chloroacetanilide compounds, alachlor, acetochlor, and metolachlor, are extensively used worldwide. Other chloroacetanilides with limited usages include propachlor, bu-tachlor, metazachlor, pretilachlor, and thenylchlor. Public environmental concerns and government regulatory requirements continue to prompt the need for reliable methods to determine residues of these herbicides. There now exist a variety of analytical methods to determine residues of these compounds in crops, animal products, soil, and water. The chemical structures and major crops in which these compounds are used are summarized in Table 1. 

Pyraflufen-ethyl was primarily developed as a cereal herbicide to control a broad spectrum of broadleaf weeds. Pyraflufen-ethyl applied in early postemergence at 12 g a.i. ha provides excellent control of some important weeds such as Anthemis arvensis, Lamium purpureum and Sinapis arvensis and good suppression of Matricaria chamomilla, Stel-iaria media, Veronica persica and Viola spp. 

Sulfentrazone is a broad-spectrum, pre-emergent herbicide that provides good control over broadleaf weeds, grasses and sedges in crops and turf. The metabolism of sulfentrazone in animals and plants is similar. The major plant metabolite of sulfentrazone is 3-hydroxymethyl sulfentrazone (HMS). The soybean tolerance of 0.05 mg kg includes residues of sulfentrazone plus its major metabolite, HMS. The rotational crop tolerance includes residues of sulfentrazone and its major metabolites, HMS and... 

Holm et al. state that across the world about 200 weed species are involved in 95% of man s weed problems as related to food production (2). They list 80 species as primary weeds and 120 species as secondary weeds. The United States has seventy percent of the world s worst weeds 24% of these are grasses, 67% broadleaf weeds, and 7% sedges. 

The broadleaf weeds responded to tillage in the same general manner when rye root residue was present, however, it does appear that the growth of all the weeds was inhibited by the presence of rye root residue. This can be seen in Table II by comparing results from the tilled treatment with and without rye root residue. In the case of common ragweed, biomass was reduced 34% (178.3 g no rye, till versus 118.3 remove mulch till), but the density increased by 69% (140 plants/2.2 m versus 280 plants/2.2 m ) when rye root... 

Study 2. The effects of wheat, oats, barley and rye mulches on three broadleaf weed species and crabgrass (Digitaria spp.) are shown in Table VI. Weed control data for the corn test at Kinston are not presented because of poor cover crop kill by the paraquat treatment. 

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

Control of broadleaf weeds with 2,4-D has posed a new problem, the invasion of fields by true grasses, which will need specific herbicides. 

This application was made between 0700 and 0830 a.m. in cool (air temp., 10 0 clear and windless weather. Both granular and emulsion formulations were incorporated to the 7.5cm depth with a disc cultivator within 15 minutes of application. A second cultivation to the same depth, but at right angles to the first, was completed within 2-3 hours. On May 20th both plots were spring-tooth harrowed for seed-bed preparation for soybean planting on the same day. The only subsequent soil disturbance was a row cultivation in late June to control a severe infestation of quack-grass control of broadleaf weeds was essentially complete with the trifluralin. 

Bentazone Acid 25057-89-0 2.55 1972 Herbicide A postemergence herbicide used for selective control of broadleaf weeds and sedges (a weed) in beans, rice, com, peanuts, mint, and others... 

Rapid growth of chemical weed control did not occur until after World War II when a herbicide was introduced by Jones in 1945 at the Imperial Chemical Industries of England 2,4-dichlorophenoxyacetic acid (2,4-D). Its utility has come from its ability to kill selectively broadleaf weeds in cereal grains, com, and cotton. It does not disturb the soil and is not persistent. 2,4,5-T was launched commercially by American Chemical Paint Co. in 1948 (now Union Carbide) to combat brush and weeds in forests, along highways and railroad tracks, in pastures, and on rice, wheat, and sugarcane. 

Pendimethalin Pesticide - herbicide used to control grasses and broadleaf weeds in crop fields and turf... 

Amino-3,5-dichloro-6-fluoro-2-pyridyloxyacetic acid, tiadenamed Sta rane, is a herbicide used to control broadleafed weeds and brush species, and certain deep-rooted perennial weeds. 3,5.6-Trichloro-2-pyridyloxyacetic acid, tradenamed Garlon, is a herbicide used for vegetation management, such as in rights-of-way. 

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. 

G-32911, simetryn Simetryn was one of the first methylthiotriazine candidates tested, but was developed slowly until it was confirmed that rice had a higher crop tolerance to simetryn than to prometryn. It found its commercial place in the transplanted rice of Japan and in other countries in the subtropical rice belt. Simetryn is used to control broadleaf weeds in mixtures with other herbicides that are active against grasses. 

---