Leaching of N,N-dimethyl-2,2-diphenylacetamide (diphenamid) was measured with bioassays in three soils; a fine sand, a silt loam, and a muck. The movement of diphenamid was reduced as the clay or the organic matter content of these soils increased. Efficiency of organic matter for adsorption of diphenamid decreased as the organic matter content of soil mixtures increased. Clay (bentonite) was less efficient than organic matter in adsorbing diphenamid. Desorption of diphenamid from muck soil was very slow.

The number of vascular bundles in the rhizomes of different ecotypes of johnsongrass (Sorghum halepense (L.) Pers.) varied from 71 to 154. The size of vascular bundles varied from 60 to 150 μ in an ecotype from California to 100 to 230 μ in an ecotype from Georgia. The size of xylem cells in these vascular bundles also varied widely, but the size of phloem cells was more constant. The number of vascular bundles in culms ranged from 43 to 123. The average number of vascular bundles in individual leaves varied from 46 to 158 for different ecotypes. The number of stomata on leaf surfaces deviated from 63 to 148/sq mm for 10 different ecotypes. An average of 95 stomata/sq mm occurred on the upper surface of johnsongrass leaves while an average of 113 stomata occurred on lower surfaces. The arrangement and size of stomata varied in different johnsongrass ecotypes.

Trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), IAA (indoleacetic acid), kinetin (6-furfurylamino purine), and their combinations in culture solutions did not affect cotton (Gossypium hirsutum L., var. Deltapine Smooth Leaf) germination but reduced primary root and shoot lengths of seedlings. Trifluralin alone and in combination with IAA or kinetin inhibited lateral root development. When IAA and kinetin were both applied with 5 ppmw trifluralin, lateral roots developed.

Sequential herbicide treatments of 3-[p-(p-chlorophenoxy)-phenyl]-1,1-dimethylurea (chloroxuron) with S-propyl dipropylthiocarbamate (vernolate) controlled weeds early in the season in soybeans (Glycine max (L.) Merr. ‘Dare’ or ‘Bragg’) better than when chloroxuron was applied in sequence with either α,α,α-trifluoro-2,6-dinitro-N,N dipropyl-p-toluidine (trifluralin) or 4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline (nitralin). The control of weeds late in the season was enhanced with split applications of 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (linuron) or 2,4-bis(isopropylamino)-6-(methylthio)-s-triazine (prometryne) when applied to plots previously treated with chloroxuron as early postemergence and trifluralin, nitralin, or vernolate applied preplant. In 1969 nitralin injured soybeans, and reduced stands and seed yields significantly more than trifluralin or vernolate. In 1970 sequential treatments of prometryne with chloroxuron and vernolate were more phytotoxic to soybeans than were the same postemergence treatments when applied with nitralin and trifluralin.

Rates of 0, 1.7, and 3.4 kg/ha of 3-amino-2,5-dichlorobenzoic acid (chloramben) were incorporated to 0, 3.8, and 7.6-cm depths in 0.7 by 0.7-m microplots under low, moderate, and high rainfall conditions. Soybean [Glycine max (L.) Merr., var. Amsoy] injury increased with increasing depth of incorporation of 3.4 kg/ha chloramben. Chloramben incorporation under low rainfall conditions significantly improved control of giant foxtail (Setaria faberii Herrm.), smooth pigweed (Amaranthus hybridus L.), and velvetleaf (Abutilon theophrasti Medic.) compared to surface treatments. Jimsonweed (Datura stramonium L.) was not controlled well by chloramben regardless of rate or incorporation depth. In larger field plots over a 3-year period, 3.4 kg/ha chloramben incorporated with a disc produced slight but insignificant soybean injury. Giant foxtail, smooth pigweed, common ragweed (Ambrosia artemisiifolia L.), and velvetleaf control with incorporated chloramben was equal to or better than the control obtained with surface-applied chloramben. Regardless of method of application, control of common cocklebur (Xanthium pensylvanicum Wallr.), jimsonweed, and annual morningglory (Ipomoea spp.) was poor.

The concentration of N,N-dimethyl-2,2-diphenylacetamide (diphenamid) required to cause 50% growth inhibition (I50) of the shoots or roots in soil, or the roots in a bioassay, was determined for several species. of the plants tested, grasses were the most sensitive, while Solanaceae were among the most tolerant to diphenamid. Based on shoot inhibition, the sensitivity difference between the sensitive foxtail millet (Setaria italica L.) and the tolerant pepper (Capsicum frutescens L.) was 150 fold. Highly significant correlations among the I50 values indicate that any of the three methods would be satisfactory for measuring the sensitivity of species to diphenamid.

Repeated postemergence treatments of 3-[p-(p-chlorophenoxy)phenyl]-1,1-dimethylurea (chloroxuron), 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (linuron), or 2-sec-butyl-4,6-dinitrophenol (dinoseb) can be applied to soybeans (Glycine max (L.) Merr.) without severe injury to the foliage throughout the growing season. However, multiple treatments of 2,4-bis(isopropylamino)-6-(methylthio)-s-triazine (prometryne) resulted in more foliar injury early in the season than from similar treatments of chloroxuron, linuron, or dinoseb. Chlorotic veination appeared in the upper leaves of soybeans treated with prometryne late in the season, and injury was greater from multiple applications than from a single application. Chloroxuron and dinoseb resulted in stem injury which increased with repeated applications. Seed yields were lower from plots treated with repeated applications of prometryne compared with untreated plots or plots treated with a single application. Multiple applications of chloroxuron, linuron, or dinoseb did not affect seed yields. Soybean stands were significantly lower in 1 year from three or four applications of linuron and four applications of prometryne compared with fewer applications of each herbicide. Seed quality was best in dinoseb-treated plots and poorest in prometryne-treated plots regardless of the number of applications.

The growth of barley (Hordeum distichum L., var. Esperanza) seedlings in nutrient solution was reduced by purple nutsedge (Cyperus rotundus L.) plants growing in connected vials and by addition of ethanolic extract of purple nutsedge. Aqueous and ethanolic extracts from subterranean parts of purple nutsedge reduced the germination and root elongation of barley; stimulations of barley root elongation were obtained with diluted aqueous extract. The germination of barley, mustard (Brassica nigra L., var. Alsace), and cotton (Gossypium hirsutum L., var. Acala 1517) was reduced in soil which had been infested previously with purple nutsedge. Radicle elongation of barley was inhibited by ethanolic extract of soil previously infested. Chromatographic studies indicated that the inhibitors are phenolic substances.

Several herbicides were tested in the greenhouse on ivyleaf morningglory (Ipomoea hederacea (L.) Jacq.), green foxtail (Setaria viridis (L.) Beauv.), purple nutsedge (Cyperus rotundus L.), and quackgrass (Agropyron repens (L.) Beauv.) to determine the degree of enhancement in activity that could be obtained with an isoparaffinic oil carrier applied at 140 L/ha. The enhancement varied with the herbicide and with the species, ranging from 16-fold enhancement with 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) and 2-sec-butyl-4,6-dinitrophenol (dinoseb) on ivyleaf morningglory to no enhancement of atrazine activity on purple nutsedge and quackgrass or (2,4-dichlorophenoxy)acetic acid (2,4-D) activity on quackgrass and ivyleaf morningglory. An oil adjuvant was less effective in enhancing dinoseb and 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (linuron) activity than was the isoparaffinic oil carrier. Also, the isoparaffinic oil carrier emulsified in water was less effective than the undiluted oil in enhancing dinoseb activity on green foxtail, even though equal volumes of the isoparaffinic oil were applied.

Foliar applications of 2-chloroethylphosphonic acid (CEPA) 7 days prior to spot applications of 14C-labelled 3,6-dichloro-o-anisic acid (dicamba) to leaves of wild garlic (Allium vineale L.) increased basipetal translocation of the dicamba as measured 7 days after dicamba treatment. High concentrations of CEPA were inhibitory. The ethylene released from CEPA degradation may have altered the metabolic “sink-source” relationships within the wild garlic plants allowing increased basipetal translocation of subsequent applications of dicamba when low concentrations of CEPA were applied.

The influence of pH, temperature, ionic strength, and protein modification on the sorption (moles of chemical bound per mole of protein) of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) and 3′,4′-dichloropropionanilide (propanil) to bovine serum albumin (hereinafter referred to as BSA) was examined. Free amino groups of BSA were involved in the binding of both diuron and propanil. In addition, tryptophanyl residues appeared to be involved in the binding of propanil. Studies made with derivatives of diuron suggested that the amide hydrogen and carbonyl oxygen of the phenylamide are involved in the binding mechanism. Conformation of the protein was suggested to control the extent of binding. Increased chlorination of the phenyl ring was correlated with increased binding onto BSA. Propanil was bound to a greater extent than diuron by the protein.

Field studies indicated that D(-) (3-chlorophenylcarbamoyloxy)-2N-isopropylpropionamide (RP-11755) at 3 lb/A controlled dodder (Cuscuta spp.) in alfalfa (Medicago sativa L.) as well as or better than the standard treatment, isopropyl m-chlorocarbanilate (chlorpropham) at 6 lb/A. Control from 2-sec-butyl-4,6-dinitrophenol (dinoseb) at 12 lb/A (amine or phenol form) sometimes was equal but never superior to that from chlorpropham. Greenhouse studies indicated that vapors toxic to dodder seedlings evolved from soil treated with dinoseb (amine or phenol form) but not from soil treated with RP-11755.

The relative susceptibility of 40 plant species to postemergence applications of 2-sec-butyl-4,6-dinitrophenol (dinoseb) in isoparaffinic oil was determined. Peanuts (Arachis hypogaea L. ‘Holland Virginia 56R’), with an I50 of greater than 2.24 kg/ha, were the most tolerant, and johnsongrass (Sorghum halepense (L.) Pers.) seedlings, with an I50 of 0.011 kg/ha, were the most susceptible. This is greater than a 200-fold difference in susceptibility, due primarily to internal tolerance, because penetration differences were reduced with the isoparaffinic oil carrier. Legumes generally were the most tolerant, and grasses ranged from tolerant to the most susceptible. Several species, primarily grasses, showed greater than 25% inhibition of shoot fresh weight from the isoparaffinic oil carrier alone.

The effect of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) and isopropyl m-chlorocarbanilate (chlorpropham) on in vivo levels of ATP in Chlorella sorokiniana Shihira and Krauss were compared. Diuron inhibited the photochemical, but not the oxidative, production of ATP, whereas chlorpropham inhibited both systems. Diuron equally inhibited growth and ATP synthesis, but chlorpropham had a stronger effect on ATP level than on growth.

The fate of 2,4-dichlorophenyl p-nitrophenyl ether (nitrofen) in the foliage of rape (Brassica campestris L. ‘Echo’), redroot pigweed (Amaranthus retroflexus L.), and green foxtail (Setaria viridis (L.) Beauv.) was investigated with the aid of 14C-nitrofen. Only limited amounts of the label were translocated in these species. Plants treated with 14C-nitrofen under high light conditions produced several labelled compounds of different molecular size and chromatographic properties. The time at which these compounds were first detectable depended on light intensity. At least two of these compounds are lipid-nitrofen conjugates or nitrofen polymers and others may be formed by cleavage of nitrofen at the ether linkage.

Seeds of dyers woad (Isatis tinctoria L.) readily germinated at temperatures from 3 to 25 C. Dyers woad seeds in their fruits, from which they do not normally dehisce, had greatly depressed germination compared to that of threshed seeds. The presence of dyers woad fruits in the same Petri dish markedly depressed germination and/or root elongation of threshed dyers woad seeds and the seeds of some competing broadleaf and grass species. The depression was especially evident on seeds of other species of Cruciferae. Similar reductions in germination or root elongation were obtained when water used to soak dyers woad fruits was used to wet germination substrates.

Early postemergence applications of 2,6-dichlorobenzonitrile (dichlobenil) granules at 15 lb/A controlled 97 to 99% of dwarf waterlily (Nymphaea tetragona Georgi) in a shallow lake for 3 years. Dichlobenil alone was superior to a combination of dichlobenil and (2,4-dichlorophenoxy)acetic acid (2,4-D) for the control of dwarf waterlily and western yellow waterlily (Nuphar polysepalum Engelm). Reinfestation was more rapid on plots 25 by 25 ft in size than on plots 50 by 50 ft in size. When a high degree of control was maintained for 2 or 3 years, rhizomes of dwarf waterlily and a 1 to 2-ft layer of hydrosoil floated to the lake surface 17 months after dichlobenil was applied.