Soil residues from annual trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N dipropyl-p-toluidine) applications were determined over a 4-year period on a Sharpsburg silty clay loam at Lincoln, Nebraska. A phytotoxic residue of trifluralin persisted in the soil for 1 or more years especially at above-normal rates of trifluralin. Repeated applications of trifluralin did not cause a significant buildup of trifluralin in the soil. There was little herbicide remaining in the soil during subsequent years from normal rates of trifluralin.

Translocation of alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl) acetanilide] in soybean [Glycine max (L.) Merrill] and wheat (Triticum aestivum L.) was primarily apoplastic with greater uptake and translocation in wheat (susceptible) than in soybean (resistant). Root-applied 14C-alachlor translocated throughout both plants. Root uptake was greater for wheat than for soybean and older leaves accumulated more than did younger actively growing tissue in both species. Foliar applications to the primary leaves of soybean and wheat resulted in some apoplastic translocation within the treated leaf of wheat but only slight translocation in soybean. Absorption of 14C-alachlor reached equilibrium at 4 hr by excised wheat root tissue, while absorption continued after 32 hr in excised coleoptile and leaf tissue. Absorption of alachlor by leaf and coleoptile tissue was greater in light than in the dark.

Benzyladenine (BA), kinetin, and gibberellic acid (GA) at concentrations of 6 × 10−4 and 4 × 10−3 M, respectively, were used to induce formation of basal bulbs above ground in rhizomes of purple nutsedge (Cyperus rotundus L.). BA plus GA induced a tropistic response in all of the rhizomes and only above ground bulbs were produced, while kinetin plus GA induced a tropistic response and bulbs formed above and below the soil surface. Control plants as well as those treated with GA, kinetin, or BA produced underground bulbs and rhizomes but no bulbs above ground. Height of above ground secondary bulbs induced by kinetin plus GA was significantly greater than those induced by BA plus GA. Transformation of primary rhizomes to shoots in the control plants did not differ significantly from transformation of those originating from plants of the various treatments. Height of primary plants of all treatments differed significantly from the controls.

The metabolism of 14C-SAN-6706 [4-chloro-5-(dimethylamino)-2-(a,a,a-trifluoro-m-tolyl)-3(2H)-pyridazinone] and 14C-norflurazon [4-chloro-5-(methylamino)-2-(a,a,a-trifluoro-m-tolyl)-3(2H)-pyridazinone] were studied in cranberry plants (Vaccinium macrocarpon Ait. ‘Early Black’) for a 36-day period. Both compounds were readily translocated with progressively more label being present in the shoot portion with time. The two compounds are demethylated to the desmethyl analogue SAN-9774 (4-chloro-5-amino-2-(a,a,a-trifluoro-m-tolyl)-3(2H)-pyridazinone). Berry samples from cuttings contained no detectable radioactivity while samples from 2 year-old cranberry plants contained 20 ppb or less.

Two greenhouse experiments were conducted to study the influence of 12 soil-applied herbicides on the sprouting and mortality of yellow nutsedge (Cyperus esculentus L.) tubers. Alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], butachlor [N-(butoxymethyl)-2-chloro-2′,6′-diethylacetanilide], cycloate (S-ethyl N-ethylthiocyclohexanecarbamate), EPTC (S-ethyl dipropylthiocarbamate), napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide], and U-27267 (3,4,5-tribromo-N,N,α-trimethylpyrazole-1-acetamide) delayed sprouting of tubers and provided 6 to 12 weeks control, but failed to kill tubers. Tubers appeared to escape injury by failing to sprout until activity of the herbicides had substantially dissipated. Herbicides known to interfere with photosynthesis, atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], bromacil (5-bromo-3-sec-butyl-6-methyluracil), methazole [2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione], prometryne [2,4-bis(isopropylamino)-6-(methylthio)-s-triazine], San-6706 [4-chloro-5-(dimethylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone], and terbacil (3-tert-butyl-5-chloro-6-methyluracil) did not delay sprouting of tubers, but killed shoots after emergence. In addition to controlling vegetative growth, the photosynthetic inhibitors killed tubers by rapidly exhausting the food reserves of these storage organs.

The translocation of foliar-applied 14C-labelled 2,4-D [(2,4-dichlorophenoxy)acetic acid] in seedlings of leafy spurge (Euphorbia esula L.) was investigated. Approximately 90% of the tracer was extracted from the tissues with 80% ethanol. Seven days after treatment 48% of the 14C in the shoot extract and 75% of that extracted from the root were identified chromatographically as 2,4-D. Translocation out of the treated leaves and into the shoot, root, and root buds was significantly increased both by decapitation of the shoot and by increasing the nitrogen supply. This effect is attributed to the marked promotion of bud growth produced by both of these treatments.

Twelve different johnsongrass (Sorghum halepense L.) clones were selected from four different regions of the United States and were grown in the greenhouse. The johnsongrass clones grew differently depending upon the environment from which they were originally obtained, suggesting that geographical ecotypes of johnsongrass exist. The parameter of growth most closely correlated to the latitude from which the plants were obtained was the time required for floral initiation. Plants from a more northern latitude consistently flowered earlier than plants obtained from a more southern latitude. Differences in height, stem number, and the weight of rhizomes, shoots, and roots also supported the hypotheses that geographical ecotypes of johnsongrass exist. Susceptibility to dalapon (2,2-dichloropropionic acid) appeared not to be correlated to the latitude from which the plants were obtained.

The response of wheat (Triticum aestivum L.) and wild oat (Avena fatua L.) to barban (4-chloro-2-butynyl-m-chlorocarbanilate) was studied as influenced by plant morphology and air temperature after application. Growth of wheat and wild oat seedlings was reduced by barban at 0.3 μg and 0.6 μg applied to the first node, respectively. Barban application to the base and midpoint of the first leaf blade required a lower dose to reduce wild oat growth than wheat growth. Increased tillering occurred from barban injury to the main culm in wheat. Wheat and wild oat susceptibility to barban increased as the post-treatment temperature decreased from 32 to 10 C. Barban selectivity for wild oats in wheat was greater at 27 and 21 C than at 16 and 10 C.

Leaf samples from Utah State University herbarium specimens of Astragalus were analyzed qualitatively for organic nitrites. Of 324 species and varieties examined, 69 (21%) were positive for nitrites. Excluding varieties, 251 species were examined, of which 56 (22%) contained nitrites. Organic nitrites were found to be stable in dried specimens for decades. Both recently collected and 80- to 90-year-old specimens of the same species or variety tested positive for organic nitrites. Astragalus species known to cause the loco syndrome in livestock did not contain nitrites. Only one seleniferous species, A. toanus Jones, synthesized moderate amounts of organic nitrites.

The competitive effects of common cocklebur (Xanthium pensylvanicum Wallr.) on soybeans [Glycine max (L.) Merr. ‘Lee 68′] were studied on Dundee silty clay loam soil from 1970 to 1972. Full-season competition by common cocklebur at 3,300, 6,600, 13,000, and 26,000 plants/ha reduced the 2-year average soybean seed yields 10, 28, 43, and 52%, respectively. Competition from common cocklebur at 100,000 plants/ha for 4, 6, 8, 10, 12, and 16 weeks after soybean emergence reduced soybean seed yields 10, 36, 40, 60, 80, and 80%, respectively. A reduction in soybean stand occurred after 12 or more weeks competition, and an increase in soybean plant height occurred after 10 or more weeks competition. When common cockleburs were removed during the first 4 weeks after soybean emergence, no further removal was required to obtain maximum soybean yield. Bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4)3H-one 2,2-dioxide] at 1.1 to 2.2 kg/ha applied over-the-top of common cockleburs and soybeans was as effective as hand removal in terminating competition provided common cocklebur plants were not flowering.

Three blended foam adjuvants increased 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] uptake from aqueous solutions by detached live oak (Quercus virginiana Mill.) leaves as compared to uptake from water alone. There were no differences in honey mesquite [Prosopis juliflora (Swartz.) D.C. var. glandulosa (Torr.) Cockerell] control with 2,4,5-T or 1:1 combinations of 2,4,5-T with picloram (4-amino-3,5,6-trichloropicolinic acid) or with dicamba (3,6-dichloro-o-anisic acid) at 0.56 kg/ha whether applied in water + 0.5% (v/v) foam adjuvant or in a diesel oil: water (1:4, v/v) emulsion. Residual life of picloram in native forages was not extended by foam carrier as compared to water, water and surfactant, and diesel oil:water emulsion as carrier. Foam generation from adjuvants with expansion ratios (ER) of two to four was less susceptible to alteration from addition of commercially-formulated herbicides than was an adjuvant with an ER of seven. Foam adjuvant ER's increased in a curvilinear fashion as water temperature was increased from 5 to 50 C.

The 6-hydroxy derivative of picloram (4-amino-3,5,6-trichloropicolinic acid) is not on the main pathway of the soil microbial decomposition sequence for picloram. Rather it may be formed in very small amounts in a competing reaction. Decarboxylation of picloram cannot be the initial reaction in this sequence and, in fact, does not occur.

Height, true-leaf area, shoot dry weight, and survival of the seedlings of four varieties of cucumber (Cucumis sativus L.) were measured for differences occurring when treated preemergence with naptalam (N-1-naphthylphthalamic acid) alone, chloramben (3-amino-2,5-dichlorobenzoic acid) methyl ester alone, or with combinations of these two herbicides. These factors were reduced, depending upon the variety of cucumber, with each of the herbicide treatments. The only reduction associated with naptalam alone was the true-leaf area of ‘Model’ and ‘Wisconsin SMR 58.’ ‘Ohio MR 17,’ ‘Model,’ and ‘Wisconsin SMR 58’ had less reduction of all measured responses than ‘Pixie’ when treated with chloramben methyl ester alone or with combinations of naptalam and chloramben methyl ester. The herbicide variety interactions present in seedling injury under greenhouse conditions were not reflected in the yields of these varieties when grown in the field. The only significant yield reduction occurring under field conditions was with the 4.48 kg/ha rate of chloramben methyl ester in the first harvest.

In a 3 year herbicide-crop rotation involving corn (Zea mays L. ‘Coker 811A’), cotton (Gossypium hirsutum L. ‘Carolina Queen’), and peanuts (Arachis hypogaea L. ‘Argentine’), uncontrolled yellow nutsedge (Cyperus esculentus L.) and annual weeds drastically reduced all crop yields. By the end of the rotation sequences, intensive cultivation throughout the rotation killed 97 to 99% of the nutsedge tubers, but this level of control depended on hand-weeding the cotton. Moderate application of herbicides killed from 78 to over 99% of the yellow nutsedge tubers, while intensive treatment with herbicides produced at least 99% kill. In addition, all annual weeds present when the experiment was initiated were controlled satisfactorily by intensive herbicide applications except Florida beggarweed [Desmodium tortuosum (Sw.) DC.] in peanuts. The major change in composition of the weed population was a reduction in yellow nutsedge and in the total number of weeds; however, certain other population shifts also seemed affected by the weed control treatments. Compared to intensive cultivation, the investment in intensive herbicide treatment produced maximum yields and highest gross profit per acre. None of the treatments affected the market grade or organoleptic characteristics of peanuts. The fatty acid content of corn and cotton changed significantly only in 1967.

Uptake of 2,4,5-T-1-14C [(2,4,5-trichlorophenoxy)-acetic acid] by immersion of honey mesquite [Prosopis juliflora (Swartz) DC var. glandulosa (Torr.) Cockerell] leaflets rapidly diminished as pH was increased from 3.5 to 9.5. Uptake diminished less rapidly as pH increased when 10-μl droplets were applied to leaflets that were kept moist. Uptake was equivalent from solutions of pH 3.5, 5.5, and 7.5; but severely reduced at pH 9.5, when leaflets were droplet treated and let dry. Uptake under dry conditions from pH 7.5 and 9.5 droplets containing 1 M NH4Cl was equivalent to uptake from pH 3.5 and 5.5 droplets lacking NH4Cl. NH4Cl had no enhancing effect on uptake at any pH when leaflets were immersed or droplet-treated and maintained moist. Low concentrations of urea had no enhancing effect on uptake at pH 9.5 by droplet-treated leaflets that were allowed to dry. Urea concentrations above 0.1 M inhibited uptake.

Effects of the inhibitors DNP (2,4-dinitrophenol) and oligomycin, and the substituted dinitroaniline herbicides, trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline], and oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) on mitochondrial tractions isolated from soybean (Glycine max L. ‘Lee’) hypocotyls were examined. Oryzalin and nitralin uncoupled succinate oxidation at the ADP-limited state 4, as did DNP. Trifluralin caused no effect on the second state 4, but inhibited oxidative phosphorylation in a manner similar to the effect of the energy-transfer inhibitor oligomycin. Studies of the interaction of these inhibitors indicate that the sites of action for these herbicides may be different.

Cogongrass [Imperata cylindrica (L.) Beauv.] was introduced into the Mobile Bay area of Alabama in 1911 or 1912. During the ensuing 60 years this rhizomatous weedy grass has spread into most of the southern portion of the state. Cogongrass has become a problem in agronomic and horticultural crops which are not intensively cultivated. Several currently available herbicides show promise of control.

Foliar abscission induced by mist blower applications of endothall [7-oxabicyclo(2,2,1)heptane-2,3-dicarboxylic acid] combined with ethephon [(2-chloroethyl)phosphonic acid] occurred within 14 days on six field-grown deciduous species. Refoliation was essentially complete after one dormant season except on pin oak (Quercus palustris Muenchh.), which exhibited shoot damage from May and June treatments. Abscission did not occur on coniferous species. Effective doses ranged from 150 to 2,400 μg/ml endothall with 4,800 μg/ml ethephon. In greenhouse experiments on white ash (Fraxinus americana L.), the most effective levels of surfactant with endothall/ethephon ranged from 0.5 to 1.3%, and a spray volume as low as one-quarter runoff gave adequate coverage.

Bensulide [0,0-diisopropyl phosphorodithioate S-ester with N-(2-mercaptoethyl)benzenesulfonamide] and trifluralin (α,α,α-trifluroro-2,6-dinitro-N,N-dipropyl-p-toluidine) were incorporated to a depth of 2.5 and 7.5 cm in sandy loam soil on the same plots in three annual applications to study the effect of incorporation depth on movement and persistence of the herbicides in furrow-irrigated soil. Bioassays and gas-liquid chromatographic assays indicated that, regardless of rainfall, both herbicides remained within the original soil zones of incorporation. Trifluralin persisted longer in soil as depth of incorporation was increased. Neither bensulide at 4.5 or 9.0 kg/ha nor trifluralin at 1.1 kg/ha persisted in appreciable amounts 12 months after treatment. At these rates, significant residues of bensulide and trifluralin were detected after 6 months only when tillage was restricted. Herbicide concentrations that persisted 6 months as determined in laboratory assays caused severe reduction in growth of field-grown sorghum [Sorghum bicolor (L.) Moench].

Tubers of purple nutsedge (Cyperus rotundus L.) were soaked in distilled water, 9.3 × 10−6M 6-benzylamino-9 (tetrahydropyran-2yl)-9 H-purine (SD8339), or 1.39 × 10−7M kinetin and sprouted in darkness. Excised plants from tubers sprouted in sand culture were grown in half-strength Hoagland solution in 50-ml erlenmeyer flasks enclosed with aluminum foil. The leaves and upper part of the stem of each plant were exposed to an illumination of 32 klux. Rhizomes as well as untreated and treated tubers were exposed to red (R), red followed by far-red (R-FR), or red followed by far-red and red (R-FR-R) monochromatic light. R, R-FR, and R-FR-R illuminations of rhizomes from untreated tubers and plants produced basal bulbs while dark controls did not. Pfr did not revert to Pr. Dark controls produced significantly fewer basal bulbs than did rhizomes of untreated tubers and plants exposed to R, R-FR, or R-FR-R illuminations. There was no significant difference between R, R-FR, and R-FR-R illuminations. Tubers treated with SD8339 or kinetin produced basal bulbs in darkness but untreated tubers did not. Rhizomes of tubers treated with SD8339 or kinetin and exposed to R illumination produced basal bulbs. There was a significant difference in the number of bulbs produced by SD8339 or kinetin treatments and R illumination in contrast with the water controls in darkness. The effect of R illumination was similar to that of SD8339 or kinetin.