Preplant Incorporation, herbicide

A number of carotenoid biosynthesis inhibitors that came later include flurtam-one [36,37], introduced in 1997, which is used as a pre-emergence and preplant incorporated herbicide. Flurtamone can be prepared in several steps from... 

Storage Store in cool, dry, well-ventilated area Uses Preemergence and preplant incorporated herbicide for control of most annual broadleaf weeds and annual grasses in milo and sweet sorghum... 

Table V compares the degradation of total 2,4-D and 2,4,5-T (n-butyl esters and acids) over six years of observations In the Kansas and Florida locations. Although the rates of application were similar, the method of application, preplant Incorporation versus subsurface Injection, resulted In significant differences In the Initial concentrations of herbicides In the plots. The acid of 2,4,5-T comprised most of the total residue after the first two years. Although some residues were recovered, especially In later years, at depths below 15 cm, the majority (90 percent) of residue was confined to the top 15 cm of soil profile. The addition of soil amendments such as lime, organic matter and fertilizer did not appreciably Increase the overall rate of disappearance of the herbicide. The addition of activated coconut charcoal, however, significantly decreased the rate of disappearance of herbicide. Six years after the charcoal plots were established, residues (primarily 2,4,5-T acid) were still present.

Rate of herbicide calculated as active Ingredient. Herbicide Injected at 10-15 cm level or preplant Incorporated In the 0-15 cm level. All plots duplicated. 

Herbicides control weeds and are the most widely used class of pesticides. The latest US EPA data show that some 578 million pounds of herbicides were used in the United States in 1997 and accounts for some 47% of pesticides used. This class of pesticide can be applied to crops using many strategies to eliminate or reduce weed populations. These include preplant incorporation, pre- and postemergent applications. New families of herbicides continue to be developed, and are applied at low doses, are relatively nonphytotoxic to beneficial plants and are environmentally friendly. Some of the newer families such as the imidazolinones inhibit the action of acetohydroxyacid synthase that produces branched-chain amino acids in plants. Because this enzyme is produced only in plants, these herbicides have low toxicities to mammals, fish, insects, and birds. 

In corn, the catalyst for adoption of preplant incorporated applications was not the introduction of an herbicide, but the introduction of safeners. The thiocarbamate herbicide S-ethyl dipropylthiocarbamate (EPTC) for corn weed control was first used in Illinois as early as 1961 however, the propensity for EPTC to injure com limited its use to 1% or less of the Illinois crop up to 1970 (Table 4.1). Dichlormid, a safener later packaged with EPTC, greatly improved crop safety and resulted in nearly one-quarter of the com acreage being treated with EPTC throughout the Corn Belt by 1976. 

Currently no herbicides are cleared for use in the U.S. to control weeds in Jerusalem artichokes. Preliminary tests with several herbicides have been reported (Table 12.1). For example, the cultivar Columbia displayed satisfactory tolerance to preplant incorporated treatments of chloramben, S-ethyl dipropylthiocarbamate (EPTC), ethalfluralin, pendimethalin, and trifluralin, although metribuzin resulted in considerable damage, manifested as chlorosis and necrosis of leaf margins, and reduced plant height. Tuber yield, however, was not increased by weed control, whether via herbicides or hand weeding, when compared to weedy control treatments (Wall et al., 1987). 

Herbicidal Activity. The subject furanones are primarily active as preemergence and preplant incorporated (PRE/PPI) materials and are moderately active when applied postemergence. The structure-activity relationships discussed below pertain to the preemergence activity. 

Butralin is a preplanting selective herbicide to be incorporated into the soil. At a rate of 1-3 kg active ingredient/ha it is selective in cotton, soybean and vegetables. Unlike the other dinitroanilines, it also has a growth-modifying action and is used for the control of tobacco sucker. 

The herbicidal properties of profluralin (CGA 10 832,14) were first described by Taylor (1973). It is a selective, preplanting incorporated soil herbicide, applied at a rate of 0.75-1.5 kg active ingredient/ha. At this rate its action lasts for one year, and it is used mainly for the control of annual grass weeds and several broad-leaved weeds. It is well tolerated by cotton, sunflower and peanut. In soybean profluralin is, besides chlomidin, the dinitroaniline herbicide that can be most safely used in overdose amounts (Harvey, 1973), and it is very effective against Setaria faberi. It can also be used selectively in several vegetables. 

The heterocyclic analogs of EL-107 showed interesting herbicidal activity as preplant incorporated (PPI) and surface applied (SA) materials (Table). At high rates (8 Ib/acre) they showed postemergence activity. When preplant incorporated and surface applied, these compounds were best described as broadleaf herbicides most effective on redroot pigweed, jimsonweed, nightshade, and mustard. Some degree of foxtail millet control was seen at 0.5 to 1.0 Ib/acre. Crop safety was seen on the cereals and corn. 

The hydroxyoxazolidinones 1 and the hydroxypyrrolidinones 2 were active as postemergence, preemergence and preplant incorporated materials. The structure activity relationships are discussed below. Three aspects of these molecules were altered in order to maximize herbicidal activity. These are 1) the substituent on the ring nitrogen 2) the substituents on either the oxazolidinone or pyrrolidinone rings and 3) the hydroxyl substituent. 

Table I. Shattercane control in corn at Saronville, NE, in 1979. All herbicides were applied preplant and incorporated immediatelyt...

Fluchloralin (BASF 3920 H, 9) is a volatile, selective preplanting herbicide used incorporated in the soil at rates ofO.S-1.5 kg active ingre ent(Anonym, 1973). Itis very slightly soluble in water (0.001 ppm) and is strongly adsorbed by the soil. It is used for selective weed control in cotton, alfalfa and vegetables. 

This selective preplanting herbicide with a range of action similar to that of the two preceding thiocarbamates is used combined with cyprazin, and incorporated in the soil for the control of grass and broad-leaved weeds and maize. Its rate of application is 2-3 kg ethiolate/ha. The trade name of the combination is Prefox . 

Pebulate is a preplanting herbicide for the control of grass and broad-leaved weeds. Like the other volatile thiocarbamates, it must be incorporated in the soil. It is tolerated by a wider range of crops than EPTC. It is used in sugar beet, tomatoes and transplanted tobacco at a rate of 4-6 kg active ingredient/ha. Its action lasts for... 

---