bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect and Persistence of Herbicides Applied to Soil in Puerto Rican Forests
Authors: Dowler Clyde C. , Forestier Wilson , Tschirley F. H.
Published: June 2019

Six herbicides were applied at 3, 9, and 27 lb/A to the soil in forests of three types in Puerto Rico. The forests differed in soil type, amount and pattern of rainfall, and species composition. Defoliation occurred slowly, but the correlation between percentage defoliation and plants killed was significant at the 1% level of probability. Some defoliation was evident 1 month after treatment and increased slowly during the next 6 to 8 months. The most effective herbicide was 4-amino-3,5,6-trichloropicolinic acid (picloram). Generally, 2-methoxy-3,6-dichlorobenzoic acid (dicamba), 2-methoxy-4,6-bis(isopropylamino)-s-triazine (prometone), and 5-bromo-3-sec-butyl-6-methyluracil (bromacil) were less effective than picloram. Both 2,3,6-trichlorophenylacetic acid (fenac) and 3-(3,4-dichlorophenyl)-l,l-dimethylurea (diuron) were ineffective. Defoliation was greatest and more plants were killed in the driest site.

One year after treatment, fenac was the most persistent herbicide in the soil. Herbicides were found to a 36 to 48-in depth within 3 months after application.

Herbaceous and woody seedlings were present at all sites within 18 months after herbicide application. There was no definite relationship between herbicidal treatment and secondary succession, except that the number and frequency of successional species were greater on plots having the highest percentage of defoliation.
The Interaction of Diphenamid and Two Soil Fungi on the Growth of Tomato
Authors: Kesner C. D. , Ries S. K.
Published: June 2019

The growth of tomato (Lycopersicoti esculentum Mill., var. Heinz 1350) plants was enhanced by low concentrations of both N,N-dimethyl-2,2-diphenylacetamide (diphenamid) and the filtrate from two fungal species Trichoderma viride (Tode) Harz and Aspergillus candidus Link. High concentrations of the filtrate from these fungi inhibited the growth of tomatoes, but this was overcome by the addition of diphenamid. Diphenamid also increased the growth of these two fungi.
Effects of Light Quality on the Life Cycles of Crabgrass and Barnyardgrass
Authors: Dunn Stuart , Gruendling G. K. , Thomas Aubrey S.
Published: June 2019

Large Crabgrass (Digitaria sanguinalis (L.) Scop.) and barnyardgrass (Echinochloa crusgalli (L.) Beauv.) plants were grown from seedlings to maturity under five light qualities of equal energy levels. For crabgrass, both fresh and dry weight yields of plant tops grown under red light and under cool white light were significantly greater than those under green, yellow, or blue light. Length of stem followed this same order. Effects of light quality on reproduction were not as consistent; green and blue light caused the largest numbers of seed heads to form, while yellow light delayed flowering and resulted in the least number and weight of seed heads. Somewhat similar responses to light were found with barnyardgrass plants, except that yields under yellow light were close to those under red light for this species. Blue light caused smallest plants in both kinds of weeds.
Annual Flower Plant Growth as Affected by Soil-Incorporated Herbicides
Authors: Adamson R. M. , Crossley J. H.
Published: June 2019

Five preplant, soil-incorporated herbicides were evaluated over a 2-year period for their effect upon the growth of representative varieties of 15 common species of spring-planted annual flowers. Of these, α,α,α,-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) was effective in combining freedom from plant injury with control of weeds. Only in phlox (Phlox nana compacta Nutt., var. Fireball) was growth reduced significantly over the 2-year period by this herbicide at 2 lb/A while petunia (Petunia hybrida, var. Snow Lady) was reduced in 1 of 2 years. N,N-dimethyl-2,2-diphenylacetamide (diphenamid) at 4 and 8 lb/A was effective and ethyl N,N-dipropylthiocarbamate (EPTC) at 4 lb/A was fairly effective, but both were tolerated by fewer flower species. N-(2-mercaptoethyl) benzenesulfonamide S-(O,O-diisopropyl phosphorodithioate) (bensulide) at 10 lb/A and methyl 3,4-dichlorocarbanilate (swep) at 5 lb/A were not phytotoxic to any species but were relatively ineffective in controlling the weeds present.
Effects of Paraquat on Yield and Composition of a Subclover-Hardinggrass Pasture
Authors: Kay Burgess L.
Published: June 2019

Annual grasses were removed by l,l′-dimethyl-4,4′-bipyridinium salt (paraquat) from subclover (Trifolium subterraneum L.)-Hardinggrass (Phalaris tuberosa L., var. stenoptera (Hack.) Hitchc.) pastures with only temporary damage to these species. If sprayed at the recommended time, total forage production was unchanged and forage quality was improved. Species composition of the pasture was improved by all spraying treatments.
Effect of Certain Quinones, Diquat, and Diuron on Chlorella pyrenoidosa Chick. (Emerson strain)
Authors: Zweig G. , Hitt J. E. , McMahon R.
Published: June 2019

The effect of 1,4-naphthoquinone, 1,4-benzoquinone, and several CI and NH2-substituted quinones has been studied on growth, chlorophyll concentration, and oxygen evolution in Chlorella pyrenoidosa Chick. (Emerson strain). Drastic decrease of the studied parameters usually was noted after 24 to 48 hr treatment at 3×10–5 M concentration. The effect of the quinones was compared with that of 6,7-dihydrodipyrido [l,2-a:2,l-c-]pyrazidinium salt (diquat) and 3-(3,4-dichlorophenyl)-l,l-dimethylurea (diuron). Diuron inhibited oxygen evolution immediately after addition, but could be washed out and the effect was reversible. Diquat had no inhibitory effect on oxygen evolution and chlorophyll content but caused a slight decrease in cell number. Although some quinones have an almost immediate effect on the oxygen-evolving mechanism, it seems more likely that the overall effect of the quinones is on the total physiological activity of the algal cells. Oxygen evolution seems to affected earlier than chlorophyll destruction, and the observed long-term damage is irreversible. Most of the compounds studied could be classified as algicidal, with the exception of diuron, diquat, and 1,4-benzoquinone which may be considered to be algistatic.
Factors Influencing the Phytotoxicity and Movement of Paraquat in Quackgrass
Authors: Putnam A. R. , Ries S. K.
Published: June 2019

Quackgrass (Agropyron repens (L.) Beauv.) was defoliated for 25 to 30 days with applications of 1.0 lb/A of l,l′-dimethyl-4–4′-bipyridinium salt (paraquat). Applications were more effective made prior to darkness than at midday. Phytotoxicity was increased by adding surfactants in the field, and experiments utilizing 14C-paraquat under controlled environmental conditions indicated that the surfactant X-77 increased foliar absorption by 20%. Quackgrass plants grown in nutrient solutions exhibited chronic paraquat toxicity which increased as the nitrogen levels increased. Paraquat also inhibited the growth of lateral buds on quackgrass rhizome segments cultured in the dark. Greater movement of 14C-paraquat in quackgrass leaves occurred under 6 hr of light as compared to 6 hr of darkness following application. However, a 6-hr dark period after application prior to the light period further enhanced the movement from the treated leaf.
Effect of Trifluralin and Nitralin on Mitochondrial Activities
Authors: Negi N. S. , Funderburk H. H. , Schultz D. P. , Davis D. E.
Published: June 2019

Oxygen uptake and oxidative phosphorylation were inhibited by 10–4 M of α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) in isolated mitochondria of corn (Zea mays L., var. Dixie 18), Sorghum (Sorghum vulgare Pers., var. Early Hegari) and Soybean (Glycine max L., var. Lee). Little or no inhibition was detectable at 10–5 and 10–6 M in corn and sorghum. Data for 4-(methylsulfonyl)2,6-dinitro-N,N-dipropylaniline (nitralin) were more variable but similar. The effects on these processes do not seem to be related to the selectivity of trifluralin since it caused a greater reduction in oxygen and phosphate uptake in resistant species (soybean) than the susceptible species (sorghum).
Radioisotopic and Gas Chromatographic Methods for Measuring Absorption and Translocation of 2,4,5-T by Mesquite
Authors: Morton Howard L. , Davis F. S. , Merkle M. G.
Published: June 2019

The uptake and transport of carboxyl-labeled and unlabeled butoxyethyl esters and ammonium salts of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) by honey mesquite (Prosopis juliflora(Swartz) DC, var.glandulosa(Torr.) Cockerell) leaves were compared as measured by liquid scintillation counting and gas chromatography. Absorption of 2,4,5-T was determined by assaying leaf-rinsing solutions and extracts of treated leaves. Transport of 2,4,5-T was measured by determining amounts of 2,4,5-T found in stem tissue. The methods of analysis gave comparable results when extraction, cleanup, and analytical procedures were identical. When cleanup and methylation procedures were eliminated for the radioisotopic analyses, radioisotopic analyses gave significantly higher values for extracts of treated leaves than did gas chromatographic analyses. Larger amounts of 2,4,5-T were recovered from leaves treated with the butoxyethyl esters of 2,4,5-T than with ammonium salts.
Physiological Changes Accompanying the Death of Cocklebur Plants Treated with 2,4-D
Authors: Cardenas J. , Slife F. W. , Hanson J. B. , Butler H.
Published: June 2019

The hypothesis that plants treated with 2,4-dichlorophenoxyacetic acid (2,4-D) die as a consequence of abnormal growth has been examined. Cocklebur (Xanthium sp) plants spot treated on one leaf with 2,4-D show three phases of growth toward death. For the first 2 days after treatment, there is a net weight increase, largely due to abnormal growth of the axis (apex, stem, and tap root). Root and leaf growth are drastically curtailed. Between 2 and 7 days, axis growth continues primarily at the expense of leaf tissue which is induced to senesce, especially the cotyledons. The last phase between 7 and 10 days leads to collapse and withering of plants, and was not examined in detail.

Analyses for nitrogenous constituents show the usual mobilization to the axis, with early and large increases in nucleic acid. Both photosynthesis and ion absorption are initially stimulated but decline sharply after the first day. Translocation to leaves and roots is drastically reduced in favor of the proliferating axis.

The death of the plant appears to be due to suppression of normal apical growth coupled with induction of abnormal axis growth. Failure to produce new root and leaf tissue plus inadequate nutritional maintenance of existing roots and leaves lead to lack of autotrophism and eventual death. The biochemical basis for these responses appears to be with aberrant nucleic acid metabolism.
Relation of Triazine Residues to Fungal and Bacterial Colonies
Authors: Fink Rodney J. , Fletchall O. Hale , Calvert Oscar H.
Published: June 2019

Rates of 0 and 5 lb/A of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) or 2-chloro-4,6-bis(ethylamino)–s-triazine (simazine) were combined with O and 200 lb/A of nitrogen fertilizer as preemergence applications on plots planted to corn (Zea mays L., var. Mo. 880) in May of 1964 and 1965. Soil samples collected in December, 1965, and again in February, 1966, were plated on Difco potato dextrose agar and nutrient agar to determine the growth of fungal and bacterial colonies. There was no difference in the total number of fungal colonies grown on media seeded with soils from the field studies, yet variation in individual species occurred. The number of bacterial colonies increased on plates seeded with soil from plots treated with 200 lb/A of nitrogen plus 5 lb/A of simazine but not from simazine-treated soil without nitrogen.
Competitive Effects of Annual Weeds on Spanish Peanuts
Authors: Hill L. V. , Santelmann P. W.
Published: June 2019

Peanut (Arachis hypogaea L.) yields were not influenced by weeds that were removed within 3 weeks after planting and each week thereafter, but a yield reduction did occur when weeds were not removed until 4 to 8 weeks after planting. Peanuts kept weed free at least 6 weeks after planting showed no yield loss due to competition from weeds emerging later. As weed competition increases, peanut seed yield, forage yield, and soil moisture content decreases.
Dissipation of Herbicides at Three Soil Depths
Authors: Harris C. I. , Woolson E. A. , Hummer B. E.
Published: June 2019

Twelve locations in the United States and Puerto Rico were the sites for determining the loss of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) and 2,3,6-trichlorophenylacetic acid (fenac) from soil. The herbicides were contained in tubes (1.88 by 6 inches) placed at depths of 3, 9, and 15 inches in the field. The samples were placed horizontally to minimize losses due to vertical movement of water from the tubes. After at least 3 months in the soil, the samples were returned to Beltsville and analyzed. Average recoveries showed 61% more atrazine and 41% more fenac from the 15-inch depth than from the 3-inch depth. Five northern samples contained more than twice as much atrazine and fenac residue as four southern samples. A positive correlation existed between fenac retention and soil organic matter content. Increasing soil organic matter and depth of placement, and decreasing temperature, tended to make the herbicides more persistent. However, the data were quite variable and the variations were often unexplainable.
Herbicidal Treatment Effect on Carbohydrate Levels of Alligatorweed
Authors: Weldon L. W. , Blackburn R. D.
Published: June 2019

We applied propylene glycol butyl ether esters of 2-(2,4,5-trichlorophenoxy)propionic acid (silvex) and 2,4-dichlorophenoxyacetic acid (2,4-D) to floating alligatorweed (Alternanthera philoxeroides(Mart.) Griseb.) and determined the level of carbohydrates in the underwater stems. The chemicals were applied at 4 and 8 lb/A on five application dates during a growing season at two sites. One month after initial application, the readily acid-hydrolyzable carbohydrates had been depleted by an average of 23.8% in a tidal area and 14.5% in a non-flowering area. Throughout the growing season, levels of carbohydrates were higher in a non-flowing area. The alligatorweed in the tidal area was more susceptible to herbicides. Regrowth from underwater nodes resulted in replenishment of the carbohydrates during the second month following treatment with 2,4-D. Carbohydrate levels remained low for 2 months following treatment with silvex, which resulted in more effective control of alligatorweed. Silvex at 8 lb/A, with retreatment after 2 months, provided the most effective control of floating alligatorweed.
Downy Brome Control by Soil-Active Herbicides for Revegetation of Rangelands
Authors: Evans Raymond A. , Eckert Richard E. , Kay Burgess L. , Young James A.
Published: June 2019

Eighteen soil-active herbicides were evaluated for control of downy brome (Bromus tectorumL.) and associated broadleaf weeds during revegetation of big sagebrush (Artemisia tridentataNutt.) rangelands in Nevada and in northeastern California. We rated all herbicides in reference to a chemical-fallow program for replacement of vegetation, where seeding follows and is separated from herbicide application by at least 1 year. Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) applied at 1 lb/A was the most promising treatment with respect to three essential characteristics: length of activity, spectrum of weed control, and relative preemergence and postemergence phytotoxicity.
Effect of Nitrogenous Materials on the Uptake of Triazine Herbicides
Authors: Minshall Wm. Harold
Published: June 2019

An application of potassium nitrate or urea to the soil of detopped potted tomato plants [Lycopersicon esculentum Mill.] increased the rate of exudation from the stumps of the plants from 100 to over 300% and increased the concentration of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine [atrazine] in this augmented exudate from 9 to 40%. Atrazine applied to the soil at 2:00 PM was detected in the stump exudate within 10 min and with an application of 3500 μg per pot it was approaching its maximum concentration by the end of 3 hr. The build-up in the concentration of atrazine in the exudate occurred at a faster rate in plants treated with potassium nitrate than in water control plants. Increasing the soil temperature from 10 to 30 C increased the rate of exudation and at each temperature an application of potassium nitrate or of urea increased the concentration of atrazine in the augmented exudate. In addition to atrazine, 2-chloro-4,6-bis(isopropylamino)-s-triazine [propazine], 2-methoxy-4,6-bis(isopropylamino)-s-triazine [prometone], and 2-methoxy-4-ethylamino-6-isopropylamino-s-triazine [atratone] were applied at 1750 and 3500 μg/pot. The concentration of these triazines in the exudate increased directly with their solubility in water. An application of urea increased the concentration of all four triazines in the exudate.
Yellow Foxtail Competition in Grain Sorghum
Authors: Feltner K. C. , Hurst H. R. , Anderson L. E.
Published: June 2019

Grain sorghum (Sorghum vulgare Pers.) was grown in combination with varying densities and durations of yellow foxtail (Setaria glauca (L.) Beauv.) during 1963-1965 at Manhattan, Kansas. Weed yield and competitive influence were greatest during the year of above-average rainfall and supplemental N fertility. Reduction in sorghum grain yield was due principally to a reduction in number of seeds per head. A 16-inch weed band on the crop row reduced soil moisture more than any other density treatment, but lesser weed densities reduced soil moisture below that of weed-free plots.
Basis for Selectivity of Linuron on Carrot and Common Ragweed
Authors: Kuratle Henry , Rahn E. M. , Woodmansee C. W.
Published: June 2019

Both carrot (Daucus carota L.) and common ragweed (Ambrosia artemisiifolia L.) plants metabolized 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (linuron). Traces of all of the following derivatives of linuron were detected in both plants: 3-(3,4-dichlorophenyl)-1-methoxyurea, 3-(3,4-dichlorophenyl)-1-methylurea, 3-(3,4-dichlorohenyl)urea, and 3,4-dichloroaniline. Differences in absorption and concentration of these derivatives were observed between carrot and ragweed plants. All of the above derivatives were phytotoxic to common ragweed plants except for 3-(3,4-dichlorophenyl)urea and 3,4-dichloroaniline, while none of the derivatives were phytotoxic to carrot. In carrot, 87% of the applied linuron was metabolized to nonphytotoxic derivatives compared to only 13% in common ragweed plants. It appears that a combination of differences in absorption, metabolism, and phytotoxicity of several of the metabolite derivatives of linuron to carrot and common ragweed plants may be the primary reason for differences in sensitivity of these two plants to linuron.
Repeated, Foliar Applications of Herbicides on Johnsongrass
Authors: Hamilton K. C.
Published: June 2019

The responses of established, spaced-planted strains of johnsongrass (Sorghum halepense (L.) Pers.) to repeated, foliar applications of herbicides were studied under irrigated desert conditions. Monosodium methanearsonate (MSMA) and disodium methanearsonate (DSMA) were the most effective herbicides. Six to 10 applications with 3 to 6 lb aihg of either herbicide (totaling 24 to 60 1b/A) killed johnsongrass in most experiments. Treatments initiated in the fall were more effective than similar treatments started in the spring. Higher rates of organic arsenicals were required to destroy topgrowth of johnsongrass in the spring and fall than during the summer. DSMA applications at 4 and 6-week intervals were more effective than applications at 8-week intervals. Six 1b/A of DSMA in 100 gpa of water applied broadcast was as effective as 400 gpa containing 6 lb aihg of DSMA applied as a spot treatment. Removing topgrowth of johnsongrass 4 or 24 hr after treatment did not reduce the effectiveness of DSMA. Combining or alternating organic arsenicals with 2,2-dichloropropionic acid (dalapon) reduced the effectiveness of the arsenicals. Susceptible strains were destroyed by five or six applications of DSMA and MSMA while 9 or 10 applications were needed to kill more resistant strains.
Seed Dormancy in Corn Chamomile
Authors: Ellis John F. , Ilnicki Richard D.
Published: June 2019

Differential germination of corn chamomile (Anthemis arvensis L.) achenes was associated with achene size. Germination increased with reduction in achene size. Lower germination of large achenes was caused by a physical restriction of embryo expansion rather than by chemical inhibition or the preventive entrance of water or oxygen through the pericarp. This physical restriction was caused by lignified portions of the pericarp surrounding the seed.
Effects of Two Environmental Factors on Removal of 2,4-DB from Forage
Authors: Linscott D. L. , Hagin R. D.
Published: June 2019

Simulated rainfall at 0.1, 0.5, and 2.0 in applied to six crops in the field previously treated with 1.5 lb/A of the dimethylamine salt of 4-(2,4-dichlorophenoxy)butyric acid (2,4-DB) resulted in an average herbicidal loss from the forage of 21, 60, and 93%, respectively. One inch of rain removed an average of 80% of 2,4-DB applied at 0.5, 1.5, and 2.0 lb/A to birdsfoot trefoil (Lotus corniculatus L.). Loss of the herbicide was attributed to the dissolving of herbicide in water and subsequent runoff from leaf surfaces, and an acceleration of herbicidal decomposition in the plant. Light interception decreased the rate of 2,4-DB breakdown in alfalfa (Medicago sativa L.) but was not considered to be of practical importance.
Leaching of Seven s-Triazines
Authors: Rodgers E. G.
Published: June 2019

Leaching of seven s-triazines in Lakeland fine sandy soil under greenhouse and field conditions was demonstrated by use of oats (Avena sativa L., var Seminole) and cucumber (Cucumis sativis L., var. Palomar) for bioassay. Depth of leaching was determined by abnormalities of these species grown in soil samples from the surface of treated soil to a depth of 22 in in the field and to 36 in in columns. Symptoms of injury by the different materials were similar and included primarily leaf chlorosis of both species and bending and breaking of cucumber stems within 7 to 10 days after planting; plants that failed to survive usually died 12 to 14 days after planting. Leaching of 2-methoxy-4-ethylamino-6-isopropylamino-s-triazine (atratone) was greatest, followed in decreasing order by 2-chloro-4,6-bis(isopropylamino)-s-triazine (propazine), 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine), 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine), 2-chloro-4-diethylamino-6-isopropylamino-s-triazine (ipazine), 2-ethylamino-4-isopropylamino-6-methylmercapto-s-triazine (ametryne), and 2,4-bis(isopropylamino)-6-methylmercapto-s-triazine (prometryne). Oats did not significantly reduce the soil concentration of ametryne and prometryne during a growing period of 56 days.
Compatibility of Chemical and Mechanical Weed Control Methods
Authors: Upchurch R. P. , Selman F. L.
Published: June 2019

Herbicides were applied postplant to field grown peanuts (Arachis hypogaea L.) and cotton (Gossypium hirsatum L.) in association with various cultivation devices. Rotary cultivations were compatible with single or multiple chemical treatments applied to soil. For eight preemergence herbicides commonly used on a nonincorporated basis, use of the multiple-application multiple-rotarycultivation technique, in comparison to the common method of use, increased the early-season weed control rating from 3.4 to 4.5 (scale 1.0 = no control, 5.0 = perfect), reduced weeds from 209 to 37 plants/50 sq ft, increased length of control from 36 to 50 days, and reduced the manual hoe time requirement from 24 to 10 hr/A. Incorporation of single or multiple chemical treatments decreased crop safety for some herbicides especially where cotton was the crop. The power driven rotary cultivator was superior to the standard sweep-equipped cultivator and the weeder for use in conjunction with multiple chemical applications. Herbicidal applications incorporated with the rotary cultivator at 0, 7, and 14; 7, 14, and 21; or 0, 14, and 28 days after planting provided equal weed control.
Winged Elm Control with Picloram and 2,4,5-T with and without Additives
Authors: Elwell Harry M.
Published: June 2019

Foliar sprays of 4-amino-3,4,5-trichloropicolinic acid (picloram) controlled winged elm (Ulmus alata Michx.) more effectively than 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). Picloram and 2,4,5-T in a mixture effectively controlled the elm. Sprays of 2,4,5-T with ammonium thiocyanate (NH4SCN) added, and a (1:1) combination of NH4SCN and 3-amino-1,2,4-triazole (amitrole) additive, controlled the elm. Foliar sprays of 2,4,5-T without additives have been relatively ineffective. Soil moisture shortage, followed by watering immediately after treatment of winged elm with 2,4,5-T-C14, increased the translocation of 2,4,5-T as compared to plants maintained in moist or dry soils.

Picloram controlled winged elm when applied with an injector or as a soil treatment. The 2,4,5-T diluted in diesel oil, applied as an injector treatment, effectively controlled winged elm.
Effect of pH on the Phytotoxicity of Prometryne Applied to Synthetic Soil Media
Authors: Weber J. B. , Perry P. W. , Ibaraki K.
Published: June 2019

Additions of montmorillonite clay and soil of high organic matter content to growth media consisting of sand and nutrient solution significantly decreased the phytotoxicity of 2-methylthio-4,6-bis(isopropylamino)-s-triazine (prometryne) to wheat [Triticum aestivum L. em. Thell. (aestivum group) “Wakeland”]. Phytotoxicity was decreased to a greater extent at pH 4.5 than at pH 6.5. The reduction in phytotoxicity was attributed to adsorption of the herbicide by the additives. A larger proportion of the prometryne was present in the protonated form at the lower pH and the increased adsorption probably resulted from the coulombic bonding of these cations to the soil additives. Adsorption mechanisms are postulated and discussed.
Metabolic Fate of Monuron and Diuron in Isolated Leaf Discs
Authors: Swanson C. R. , Swanson H. R.
Published: June 2019

Leaf discs of cotton (Gossypium hirsutum L.), broadleaf plantain (Plantago major L.), soybeans (Glycine max Merrill), and corn (Zea mays L.) were incubated 1 hr in aqueous solutions of methyl- or ring-labeled 3-(p-chlorophenyl)-l,l-dimethylurea-14C (monuron) or carbonyl-labeled 3-(3,4-dichlorophenyl)-l,l-dimethyl-urea-14C (diuron). The loss of herbicide and formation of metabolites were determined at approximately 1-hr intervals up to 7 hr. Cotton leaf discs actively metabolized monuron to l-(p-chlorophenyl)-3-methylurea (monomethylmonuron), l-(p-chlorophenyl)urea (p-chlorophenylurea), and p-chloroaniline. Plantain leaf discs strongly metabolized diuron to l-(3-,4-dichlorophenyl)-3-methylurea (monomethyldiuron) and l-(3,4-dichlorophenyl)urea (3,4-dichlorophenylurea). Plantain degraded monuron less actively than diuron and cotton degraded diuron less rapidly than monuron. In soybean leaf discs, metabolism did not progress beyond the first demethylation, and corn leaf discs were unable to metabolize the herbicides in short-term studies.
Persistence and Movement of 2,3,6-TBA in Soil
Authors: Phillips W. M.
Published: June 2019

Persistence and movement of 2,3,6-trichlorobenzoic acid (2,3,6-TBA) in a silty clay loam soil was studied. Single applications of 16 lb/A 2,3,6-TBA were made to field plots on 21 dates from 1955 to 1965. All treated plots were sampled to a depth of 8 ft in 1966, and a few were sampled to a depth of 11 ft. One-foot increments of soil were bioassayed to determine presence of the herbicide. Variation in amount and depth of penetration of 2,3,6-TBA was noted, but the herbicide had persisted in the soil 11 years. Persistence and movement could not be related to moisture before or after treatment, temperature after treatment, or, except for treatments applied in 1964 and 1965, time between treatments and sampling. Residues from fall applications appeared to be slightly greater than those from spring or summer applications.
Herbicidal Persistence in Soil and its Effect on Purple Nutsedge
Authors: Waters W. E. , Burgis D. S.
Published: June 2019

Two field experiments were conducted to determine the soil persistence, crop toxicity, and effectiveness of four herbicides in controlling purple nutsedge (Cyperus rotundus L.). Excellent control of purple nutsedge was obtained with 2,6-dichlorobenzonitrile (dichlobenil) and good control was obtained with N-hydroxy-methyl-2,6-dichlorothiobenzamide. Both 3-iert-butyl-5-chloro-6-methyluracil (terbacil) and 5-bromo-3-teri-butyl-6-methyluracil were effective in controlling purple nutsedge, but maximum control was not obtained until 9 to 12 months after these chemicals were incorporated in the soil. Toxicity of all chemicals to beans (Phaseolus vulgaris, var. humilis L., Blue Lake), corn (Zea mays var. rugosa L., Golden Security), summer squash (Cucurbita moschata Duchesne, var. Yellow Crookneck), tomato (Lycopersicum esculentum Mill., var. Flora-del), and gladiolus (Gladiolus hortulanus Bailey, var. Friendship) increased as the rates were increased and decreased with time after treatment. Infestation of purple nutsedge from escaping tubers increased as the herbicidal persistence decreased.
Response of Oak and Red Maple to Herbicides Applied with an Injector
Authors: Sterrett John P.
Published: June 2019

Injections with 4-amino-3,5,6-trichloropicolinic acid (picloram), 2-methoxy-3,6-dichlorobenzoic acid (dicamba), and butoxyethanol ester of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) satisfactorily killed the tops of scarlet oak (Quercus coccinea L.) and white oak (Quercus alba L.) when applied in March or June. Triethylamine salt of 2,4,5-T adequately killed the tops of the oaks in June but not in March. Picloram was the most lethal herbicide used on red maple (Acer rubrum L.), and sprouting was controlled more effectively on all species with picloram than with the other herbicides.
Effects of 2,4-D and Other Herbicides on Oxidative Phosphorylation in Mitochondria from Cabbage
Authors: Lotlikar Prabhakar D. , Remmert LeMar F. , Freed Virgil H.
Published: June 2019

The effects of 22 herbicides on oxidative phosphorylation in mitochondria from cabbage (Brassica oleraceavar.capitataL.) have been studied. Carbamates, phenoxyacids, 3,5-dimethyltetrahydro-l,3,5,2H-thiadiazine-2-thione (DMTT),N-1-napthylphthalamic acid (NPA), 2,3,6-trichlorobenzoic acid (2,3,6-TBA), 3-(p-chlorophenyl)-1,1-dimethylurea (monuron), and 2-chloro-2-N,N-diallylacetamide (CDAA) inhibited phosphorylation to a greater extent than oxygen uptake in cabbage mitochondria. The compounds 1,2-dihydropyridazine-3,6-dione (MH), 2,2-dichloropropionic acid (dalapon), 2,2,3-trichloropropionic acid (hereinafter referred to as 2,2,3-TPA), sodium chlorate, and 3-amino-l,2,4-triazole (amitrole) at concentrations as high as 1 × 10–2M did not have a large effect on oxidative phosphorylation in cabbage mitochondria. Respiration which was stimulated by 2,4-dinitrophenol (DNP) or adenosine diphosphate (ADP) was inhibited by 2,4-dichlorophenoxyacetic acid (2,4-D). Although 2,4-D did not affect Mg++-stimulated adenosine triphosphatase (ATPase), it inhibited an oleate-stimulated ATPase activity and the ATP-32Pi exchange reaction in cabbage mitochondria. The results suggest that 2,4-D may inhibit respiration in cabbage mitochondria by an effect on a reaction involved in coupling phosphorylation with electron transport.
Phototoxicity and Persistence of Four Thiocarbamates in Five Soil Types
Authors: Koren Ephraim , Foy Chester L. , Ashton Floyd M.
Published: June 2019

The phytotoxicity and the persistence of ethyl N,N-dipropylthiocarbamate (EPTC), S-propyl butylethylthiocarbamate (pebulate), ethyl N-ethyl-N-cyclohexylthiocarbamate (hereinafter referred to as R-2063), and S-2,3-dichloroallyl N,N-diisopropylthiolcarbamate (diallate) were studied in nutrient solution and in five soil types. Both in nutrient solution and in soil, EPTC was the most toxic to barnyardgrass [Echinochloa crusgalli (L) Beauv.], followed in order by pebulate, R-2063, and diallate. Herbicidal injury, as reflected by the morphological aberrations that occurred in treated plants, was much more severe than the reduction in fresh weight. Thus, toxicity studies based on plant height had greater validity than those based on weight. The initial toxicity of each herbicide was high in those soils low in organic matter and low in soils high in organic matter. The persistence of the four thiocarbamates in the soil was associated primarily with adsorptive forces and microbial degradation. In a soil with extremely large or small adsorptive capacity, there was rapid inactivation of the herbicides because of strong adsorption to the colloids or lack of adsorption with consequent loss by volatilization. Under the latter conditions, the microbial breakdown played only a secondary role. The herbicides persisted longer in soils with more moderate adsorptive capacities but were subjected to more striking degradation by microorganisms. The patterns and rates of inactivation of the four herbicides in a given soil were quite similar. A particular concentration of each herbicide stimulated growth in barnyardgrass, as reflected both in the fresh weights and in the heights of the plants. The nature of this stimulation was not determined.
Interaction of EPTC and DNBP on Seedlings of Alfalfa and Birdsfoot Trefoil
Authors: Linscott D. L. , Hagin R. D.
Published: June 2019

In 1965 and 1966, alfalfa (Medicago sativa L., var. Cayuga) and birdsfoot trefoil (Lotus corniculatus L., var. Viking) were seeded in soil treated just before planting with ethyl N,N-dipropylthiocarbamate (EPTC). To determine herbicidal interaction on a field scale, 4,6-dinitro-o-Sec-butylphenol (DNBP) was applied as a postemergence treatment. No significant interaction of EPTC and DNBP was evident on legume or weedy grass stands on yield. Interaction of EPTC and DNBP on control of annual broadleaf weeds was noted 1 year but not the second. DNBP but not EPTC significantly reduced birdsfoot trefoil stands during both years and reduced alfalfa stands 1 year but not the other. EPTC controlled annual and perennial weed grasses and DNBP controlled annual broadleaf weeds successfully. The incorporation of EPTC in soil before planting alfalfa and birdsfoot trefoil followed by a postemergence DNBP treatment was considered to be a practical weed control method.
The Effect of Linuron on32P and45Ca Uptake in Tomato and Parsnip
Authors: Hogue E. J.
Published: June 2019

The effects of sublethal and lethal levels of 3-(3,4-dichlorophenyl)-l-methoxy-l-methylurea (linuron) on the uptake of32P and45Ca were tested on tomato (Lycopersicum esculentumMill., var. Kokomo) and parsnip (Pastinaca sativaL., var. Harris Model). Both levels of foliage-applied linuron stimulated the uptake of32P from nutrient culture solution and its translocation to the leaves. The increased32P in the leaves of the treated tomato plants was found in the inorganic phosphate fraction. Incorporation of the label in the phospholipid and nucleic acid fractions was decreased slightly. Linuron inhibited uptake and translocation of45Ca in both plants.
The Effect of Linuron on Ion Uptake in Corn, Soybean, and Crabgrass
Authors: Nashed R. B. , Ilnicki R. D.
Published: June 2019

An increase in Ca and SO4 uptake from nutrient solution in juvenile corn (Zea mays L. var. N. J. 9), soybean (Glycine max (L.) Merr., var. Kent) and large crabgrass (Digitaria sanguinalis (L.) Scop.) was obtained with 3-(3,4-dichloroyhenyl)-l-methoxy-l-methyl-urea (linuron) treatment. The uptake of K, Mg, NO3, and PO4 also was followed and varied with the ion and species.
Inhibition of Lipid Synthesis by Certain Herbicides
Authors: Mann Jay D. , Pu Minn
Published: June 2019

Thirty herbicides were tested for possible effects upon the incorporation of radioactivity from malonic acid-2-14C into lipid by excised hypocotyls of hemp sesbania (Sesbania exaltata (Raf.) Cory). Concentrations of 1 to 20 mg/L were used. Inhibition was caused by 3-nitro-2,5-dichlorobenzoic acid (dinoben), 2-chloro-N,N-diallylacetamide (CDAA), 2-chloroallyl diethyldithiocarbamate (CDEC), 7-oxabicyclo(2.2.1)heptane-2,3-dicarboxylic acid (endothall), 2,6-dichlorobenzonitrile (dichlobenil), 3,5-diiodo-4-hydroxybenzonitrile (ioxynil), and pentachlorophenol (PCP). At 1 mg/L, stimulation was caused by 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 4-amino-3,5,6-trichloropicolinic acid (picloram), and 3-amino-2,5-dichlorobenzoic acid (amiben).
Inhibition of Cotton and Soybean Roots from Incorporated Trifluralin and Persistence in Soil
Authors: Oliver Lawrence R. , Frans R. E.
Published: June 2019

Inhibition of cotton (Gossypium hirsutum L.) and soybean (Glycine max (L.) Merr.) lateral roots by alpha, alpha, alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) was directly related to depth and method of incorporation. Root inhibition of the crop plants was reduced when trifluralin was incorporated shallowly after planting with either a power tiller or a ground-driven tiller, to a depth no greater than 0.5 in above seed placement. A bioassay of the soil showed that disking trifluralin-treated plots before bedding caused the greatest retention of the material 3 weeks later, and that retention was less when the herbicide was applied and shallowly incorporated after planting. Further studies on the relationship of soil persistence of trifluralin to depth of incorporation 6 months after application, showed no herbicide present in plots not incorporated while only minimal residues were found where incorporation was no deeper than 1 in. Residues in plots incorporated below the 2-in depth were moderate at 0.5 to 1 lb/A rates and high at the 2 lb/A rate and above.
Competition Between Wheat and Wild Buckwheat
Authors: Fabricius L. J. , Nalewaja John D.
Published: June 2019

An experiment was conducted comparing wheat (Triticum aestivum L., var. Pembina) and wild buckwheat (Polygonum convolvulus L.) grown alone in pots, in full competition, and in root competition at three levels each of soil fertility and soil moisture, and harvested at three dates.

Wheat was a better competitor than wild buckwheat when considering dry matter production. With each succeeding harvest, the dry matter production and the total nitrogen and phosphorus uptake increased more for plants grown alone than in competition. Competition caused a reduction in the nitrogen and phosphorus content of wheat and wild buckwheat at the first harvest, while reductions in dry matter did not occur until the second harvest. Wheat increased in dry matter and nitrogen more than wild buckwheat with each higher level of soil moisture when grown alone but not when in competition. When grown alone or in competition, wheat increased linearly in dry matter production with increases in fertility while wild buckwheat produced maximum dry matter with medium fertility. The total nitrogen increased in wheat and wild buckwheat with each higher level of fertility, while total phosphorus increased only in wheat.

Wild buckwheat used less water than wheat to produce a gram of dry matter and per milligram of phosphorus uptake when grown alone, while the plants in competition were intermediate in water usage to plants grown alone. Wild buckwheat and wheat used similar amounts of water per unit of nitrogen uptake when grown alone and increased their water usage when grown in competition. Water efficiency for nitrogen and phosphorus uptake and dry matter production usually decreased with plant maturity and higher soil moisture, and increased with higher soil fertility.
Root Development of Rush Skeletonweed
Authors: Rosenthal Russell N. , Schirman Roland , Robocker W. C.
Published: June 2019

In 1965–66, we observed root development of two plant types of rush skeletonweed (Chondrilla juncea L.). Rosette bud formation on both plant types occurred on the upper 5-cm zone of the taproot after seed dispersal in the fall until flower-stem initiation the following spring. Incubation at various temperatures of lateral root sections from field grown plants showed a cyclic sprouting pattern with the highest percentage during late fall and early spring, and no sprouting during June. Bud production was most frequent at the proximal end of the sections. The earlier-flowering plant type contained an average of 6.7 and 6.0 major roots after 6 and 18 months of growth whereas the late-flowering type contained 10.7 and 16.0 major roots for the same periods of growth. The early-flowering plant roots were larger in diameter than those of the late-flowering plants. Both root types increased in diameter as distance from the point of attachment increased excluding root apex. Unattached secondary plants resulting from vegetative propagation were found of both plant types.
Persistence of Benzoic and Phenylacetic Acids in Soils
Authors: Sheets T. J. , Smith J. W. , Kaufman D. D.
Published: June 2019

In a greenhouse experiment, dosages of 2-methoxy-3,6-dichlorobenzoic acid [dicamba] and 2-methoxy-3,5,6-trichlorobenzoic acid [tricamba] required initially to reduce fresh weights of snap beans (Phaseolus vulgaris L.) 50% (hereinafter referred to as ED50 values) increased as clay and organic matter increased in five soils. In all soils, 2,3,6-trichlorobenzoic acid [2,3,6-TBA] was about equally toxic, but ED50 values for 2,3,6-trichlorophenylacetic acid [fenac] and 2-methoxy-3,6-dichlorophenylacetic acid [hereinafter referred to as methoxy fenac] decreased as clay and organic matter increased. Under experimental conditions of alternately moist and dry soil, phytotoxicity of dicamba, tricamba, and methoxy fenac decreased with time, but that of 2,3,6-TBA and fenac remained approximately the same for about 22 months. When soils were maintained moist throughout the incubation period, 3-amino-2,5-dichlorobenzoic acid [amiben] was least persistent, dicamba intermediate, and 2,3,6-TBA and fenac most; under these conditions, phytotoxic effects of 2,3,6-TBA and fenac decreased with time. In soil-enrichment studies, fenac, methoxy fenac, dicamba, and 2,3,6-TBA, in comparison with 2,4-dichlorophenoxyacetic acid [2,4-D], appeared very resistant to microbial degradation.
Residual Phytotoxicity of Fluometuron in Soils
Authors: Darding Roger L. , Freeman J. F.
Published: June 2019

Initial and residual phytotoxicity of 3-(m-trifluoromethylphenyl)-1, 1-dimethylurea (fluometuron) in seven soils was studied under greenhouse condition, using oats (Avena sativa L., var. Brave) as the bioassay species. The phytotoxicity of fluometuron in four of the soils, with an organic matter range of 1.0 to 5.0%, was not different at any one of the five cropping periods. Inactivation of fluometuron was more rapid in Eden silty clay loam with 3.3% organic matter than in Maury silty clay loam/silt loam with 7.2% organic matter. Phytotoxicity was significantly correlated with organic matter and soluble phosphorus during the first two cropping periods, and with cation exchange capacity, exchangeable calcium, total exchangeable bases, and soluble phosphorus during the last three croppings.
Incorporation of Dichlobenil in Mulches
Authors: Lanphear F. O.
Published: June 2019

Safer methods of herbicide application are needed for irregular planting areas. The herbicide 2,6-dichlorobenzonitrile (dichlobenil) was incorporated into various organic mulches so that a specified depth of mulch delivered the desired concentration of herbicide. The incorporation technique provided equal or better weed control than either the dichlobenil or mulch used alone. In addition, prolonged effect of the dichlobenil was realized into the second year when it was incorporated into the mulch. Increasing the mulch depth to 4 inches increased the weed control. A nutrient supplemented mulch in conjunction with the dichlobenil increased the growth of many woody ornamental plants as much as 300 to 400%.
Cultivation and Herbicides for Weed Control in Corn
Authors: Buchholtz K. P. , Doersch R. E.
Published: June 2019

Corn (Zea mays L.) plots receiving broadcast spray applications of triazine herbicides without cultivation yielded as much as plots receiving the standard two cultivations for weed control. One cultivation resulted in an average 6% increase in corn grain yield on herbicide treated plots. This yield increase probably was due to improved weed control. Weed growth reduced grain yields an average of 1.23 bu/A for each 100 lb/A of dry weeds. In some experiments, increases in corn yield due to improved weed control by cultivation on plots treated with herbicides were less than increases expected based on weed growth reductions. This disparity may have been due to injury to the corn by cultivation.
Temperature and Annual Growth Cycle Effects on Root Suckering in Black Locust
Authors: Sterrett J. P. , Chappell W. E. , Shear G. M.
Published: June 2019

The effects of temperature and the annual growth cycle on the formation of root suckers were determined by propagating root cuttings of black locust (Robinia pseudoacacia L.). The percentage of cuttings which formed suckers in an air temperature of 60 F was significantly lower than that of cuttings at 70 to 80 F. In the annual growth cycle experiment, cuttings removed in June formed significantly fewer suckers than those removed during January, March, August, or November.
Weed Competition in Rice
Authors: Smith Roy J.
Published: June 2019

Barnyardgrass [Echinochloa crusgalli (L.) Beauv.], duck-salad [Heteranthera limosa (Sw.) Willd.], hemp sesbania [Sesbania exaltata (Raf.) Cory], and northern jointvetch [Aeschynomene virginica (L.) B.S.P.] significantly reduced rice [Oryza sativa L.] yields. Damage to rice increased as populations of barnyardgrass, hemp sesbania, and northern jointvetch increased. Barnyardgrass and duck-salad lowered yields during early season, but hemp sesbania and northern jointvetch decreased yields in late season.
Weed Control in a Winter Wheat-Fallow Rotation
Authors: Burnside O. C. , Fenster C. R. , Domingo C. E.
Published: June 2019

Weed control during the fallow year and yields of subsequent winter wheat (Triticum aestivumL.) were lower on unsprayed plots than on plots treated with 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) at 2 lb/A or 3-amino-l,2,4-triazole (amitrole) at 1/2lb/A plus 3-(p-chlorophenyl)-l,l-dimethylurea (monuron) at 1 lb/A. The moldboard plow gave the most effective weed control in the winter wheat-fallow rotation followed by the oneway and the sweep plow. Sweep plow tillage left the greatest amount of plant residues on the soil surface to prevent wind and water erosion, but it did not consistently destroy shallow-rooted downy brome (Bromus tectorumL.) plants. Average downy brome stands in winter wheat on fallow plots tilled with the sweep plow, oneway, and moldboard plow were 331, 114, and 16 plants per 54 sq ft, respectively. Winter wheat yields averaged for the sweep plow, oneway, and moldboard plow treatments were 17, 18, and 20 bu/A, respectively. The most feasible method of controlling weeds in a winter wheat-fallow rotation, found in this study, was oneway tillage in combination with the lower herbicide rates.
Gross Morphological and Cytological Effects of Nitralin on Corn Roots
Authors: Gentner W. A. , Burk L. G.
Published: June 2019

The gross morphological effects of the herbicide 4-methyl-sulphonyl-2,6-dinitro-N,N-dipropylaniline [nitralin] on roots of corn (Zea maysL., var. U. S. 13) suggested abnormal cytological behavior. Roots of corn plants treated preemergence with nitralin developed digitate to globose swelling in the region of active cell division of the root tip. Cytological examination of the affected area showed that the effects of the herbicide were prevention of cell wall formation, enlargement of cells, and extensive replication of nuclei, and suggests that a primary effect of nitralin is on cell division and that this may be a primary mechanism of action as a herbicide.