We constructed a foam applicator capable of creating 300 to 400 gal of foam from 1 gal of water. The equipment was successful for applying herbicides in cotton (Gossypium hirsutum L., var. Stoneville 213) and soybeans (Glycine max Merr., var. Lee) after emergence. Weed control was equal with applications in foam as compared to conventional applications in water sprays. Foam production was highly dependent on the type and concentration of surfactant used. Various additives increased foam persistence in laboratory studies. However, for maximum effectiveness under field conditions, additives are needed that are more effective in increasing foam persistence than the ones evaluated.

Seven substituted dinitrobenzamine herbicides were evaluated at two rates as preplant soil-incorporated treatments for 2 yr. Herbicides were applied broadcast and incorporated 7 cm deep into a sandy loam with a power-driven rototiller before the preplanting irrigation and 3 weeks before crop planting. Cotton (Gossypium hirsutum L. ‘Acala SJ-1’) stands were reduced by the higher rate of nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline], dinitramine (N4,N4-diethyl-a,a,a-trifluoro-3,5-dinitrotoluene-2,4-diamine), fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], and AN 56477 [N,N-di-(2-chloroethyl)-2,6-dinitro-4-methylaniline]. Cotton yields were reduced by the higher rate of nitralin, dinitramine, and AN 56477. The poorest weed control was obtained with the lower rate of nitralin, AN 56477, and butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine]. A bioassay with Japanese millet [Echinochloa crus-galli (L.) Beauv. var. frumentacea (Roxb.) Wight] and grain sorghum [Sorghum bicolor (L.) Moench] was used to evaluate herbicides remaining in soil sampled 1, 120, and 240 days after application. Residual herbicide phytotoxicity at 240 days indicated dinitramine < trifluralin (a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) = butralin < profluralin [N-(cyclopropylmethyl)-a,a,a-trifluoro-2,6-dinitro-N-propyl-p-toluidine] = AN 56477 < nitralin < fluchloralin. In greenhouse experiments, cotton taproot elongation was retarded by both rates of nitralin, dinitramine, and AN 56477 and by the higher rate of fluchloralin. All herbicides inhibited lateral roots of cotton in the herbicide-treated zone of soil, but butralin and profluralin caused the least inhibition.

Yellow nutsedge (Cyperus esculentus L.) control with herbicides was evaluated with and without competition from turfgrasses. Postemergence applications of cyperquat (1-methyl-4-phenylpryidinium) provided safe selective control of yellow nutsedge in Kentucky bluegrass (Poa pratensis L. ‘Merion’), perennial ryegrass (Lolium perenne L. ‘Manhatten’), and red fescue (Festuca rubra L. ‘Pennlawn’). Pre- and post-emergence applications of perfluidone {1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl] methanesulfonamide} controlled yellow nutsedge when rainfall or irrigation was adequate for good turfgrass growth. Under dry conditions, perfluidone slightly injured Kentucky bluegrass and gave poor control of yellow nutsedge. Bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4)3H-one2,2-dioxide] was less effective than cyperquat or perfluidone for yellow nutsedge control and required split applications. Bentazon did not injure Kentucky bluegrass. Napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] and Vel 3973 [N-(2,4-dimethyl-5-{[(trifluoromethyl)sulfonyl]amino}phenyl)acetamide] did not provide adequate yellow nutsedge control. Vel 5052 {2-chloro-N-(2,6-dimethyl-phenyl-N-[(1,3-dioxolan-2-yl)methyl] acetamide}showed promise for yellow nutsedge control.

A new urea compound, 1-(α,α-dimethylbenzyl)-3-p-tolylurea (hereinafter referred to as K-223) is characterized by its selective control of cyperaceous weeds. This compound does not show any Hill reaction inhibition or foliar contact toxicity. Its main effect is toxicity to roots. K-223 selectively controls slender spikerush [Eleocharis acicularis (L.) R. & S.], purple nutsedge (Cyperus rotundus L.) and annual cyperaceous weeds. It is practically nontoxic to most broadleaf weeds. As the selectivity between crops and grass weeds is high, K-223 is applicable with little phytotoxicity. Thus sowing or transplanting is possible even just after application of K-223.

Greenhouse experiments were conducted to assess the storage of nonstructural carbohydrates in the stems and roots of honey mesquite and their mobilization and utilization following defoliation by hand or clopyralid. All leaves were removed by hand from one group of plants while leaving stems intact. Another group received a foliar spray of clopyralid at a sublethal acid equivalent rate of 0.07 kg ha−1. Samplings at treatment on day 0 and at 14, 28, 42, and 58 d after treatment measured leaf area; dry weight of leaves, stems, and roots; and grams and percent total nonstructural carbohydrates in stems and roots. Controls accumulated dry weight and grams total nonstructural carbohydrates in stems and roots, while maintaining a constant percent total nonstructural carbohydrates throughout the experiment. Percent and grams total nonstructural carbohydrates in stems and roots of hand defoliated plants decreased by about one-half from day 0 to 14 as new leaf growth occurred, but increased and returned to pretreatment levels on day 28. A similiar, though slower, pattern of decline and recovery of total nonstructural carbohydrates in stems and roots occurred in response to defoliation by clopyralid. These results showed that the nonstructural carbohydrates in stems and roots of honey mesquite were important sources of carbohydrates to support new leaf regrowth following defoliation by hand or herbicide.

Three adjuvants, ARD 54, ARD 93, and ARD 1836, were evaluated for their ability to reduce metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] phytotoxicity to soybeans [Glycine max (L.) Merr.] in sandy soils. A reduction in metribuzin phytotoxicity was observed, usually without reductions in sicklepod (Cassia obtusifolia L. # CASOB) control. The addition of linseed oil to a spray suspension containing 1% ARD 1836 reduced sicklepod control slightly at one of two locations. The addition of these adjuvants and linseed oil to the spray solution had no effect on soybean yield. These adjuvants slightly reduced movement of metribuzin in thin-layer soil chromatography but had no influence on sorption in batch-equilibrium experiments.

Simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] was applied annually at 4.5 kg/ha to uncultivated sandy loam of peach (Prunus persica Batsch) for 7 yr (orchard A) and 9 yr (orchard B). Simazine and the metabolite, hydroxysimazine [2-hydroxy-4,6-bis (ethylamino)-s-triazine] as determined by gas chromatography (GC) persisted for 40 and 28 months in soil of orchard A and B, respectively. However, no progressive accumulation of either compound in large quantities occurred from repeated annual applications of simazine to the orchard soils. No metabolites other than hydroxysimazine were detected. Hydroxysimazine was degraded more slowly than simazine and the residue levels of hydroxysimazine were at least 40 times those of simazine 40 months and 28 months after the final application in orchard A and B, respectively. Both simazine and hydroxysimazine residues were detected in the upper 30 cm of the soil profile.

Purple nutsedge (Cyperus rotundus L.) and yellow nutsedge (C. esculentus L.) appeared to be equally acceptable for oviposition by caged Bactra verutana Zeller, but purple nutsedge was significantly more suitable as a host: 90% of the larvae survived to maturity on purple nutsedge compared with 65% on yellow nutsedge. Responses of the plant species to both larval feeding injury and plant density were similar but purple nutsedge tended to be injured more than yellow nutsedge. At a high shoot density (nine shoots per pot), production of tubers by purple nutsedge was more adversely affected by feeding of five larvae per shoot than was production by yellow nutsedge: tuber dry weights were reduced 93 and 80% and numbers of tubers per pot were reduced 77 and 62%, respectively. Production of inflorescences was greatly reduced in both species. The effect of B. verutana on inflorescences may be more important for yellow nutsedge, which is generally considered to reproduce freely by seeds. Both species of nutsedge probably would be about equally affected by augmentation of B. verutana populations as a method of biological control.

WeedML is a proposed standard to formulate models of weed demography (or perhaps even complex models in general) that are both transparent and straightforward to reuse as building blocks for new models. The paper describes the design and thoughts behind WeedML which relies on XML and object-oriented systems development. Proof-of-concept software is provided as open-source C++ code and executables that can be downloaded freely.

Rates of photosynthesis, respiration, and transpiration of wheat (Triticum aestivum L., var. Gaines) were determined as functions of time, under controlled conditions of moderate soil water stress and soil temperature, after treatment of the roots with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron). Air temperature, relative humidity, light intensity, and air movement were maintained constant. The rate of photosynthesis declined with time for all plants treated with diuron but not for the controls. No change in the rate of respiration was detected. The rate of transpiration decreased slightly immediately upon application of the diuron and then remained constant. The data indicate that soil temperature and soil water stress play important roles in the herbicidal action of diuron applied to the soil.

Amitrol (3-amino-1,2,4-triazole) has received considerable attention in recent years as a herbicide and defoliant. This material was noted to have growth-inhibiting and defoliating properties by Hall et al. in 1952. Hall et al. reported that amitrol caused chlorophyll destruction under certain conditions and that chlorophyll synthesis was impaired in tissues formed at the time of, or subsequent to, absorption of the chemical. These workers also reported that cotton treated with amitrol showed a loss approximately 50 percent of the original reducing sugars and sucrose. Herbert and Linck have reported an initial increase in the rate of respiration of Canada thistle following treatment with amitrol. This initial respiratory increase was followed by a decrease which was dependent upon time as well as the concentration of amitrol applied to the plants. Similar results were obtained by Miller and Hall using Avena sections and cotton leaf discs. Heim et al. found that amitrol caused decreases in catalase activity of certain plants. Reduction of chlorophyll content and catalase activity were obtained following application of amitrol to leaves of potato, barley, and sunflower. In experiments reported in a more recent paper by these workers, amitrol caused in vitro inhibition of catalase activity.

The use of Isopropyl N-Phenyl Carbamate (IPC) as a residual pre-emergent herbicide depends on the effective concentration remaining in the soil for a period of time. The effectiveness of such a treatment has been shown to be dependent upon several factors.

High concentrations of arsenic (As) may be expected on Coastal bermudagrass forage harvested soon after application of organic arsenicals for weed control. Stage of plant development at treatment, rainfall between treatment and harvest, rate of application of arsenical herbicides, and the amount of growth between treatment and harvest are factors influencing As residue levels in harvested material. Regrowth following removal of treated growth had a lower As concentration. Treatment application on short grass and removing and discarding the treated foliage appeared to be the most effective means of reducing As residues.

Yellow nutsedge is one of the most problematic weedy sedges in rice–soybean systems of the Mississippi Delta region. An acetolactate synthase (ALS)-inhibiting, herbicide-resistant (Res) yellow nutsedge biotype was recently documented in eastern Arkansas, which showed intermediary growth habit between yellow nutsedge and purple nutsedge and also exhibited differential photoperiodic sensitivity to flowering. The objectives of this study were to: (a) determine variation in reproductive characteristics of the Res biotype and three susceptible (Sus) yellow nutsedge biotypes, (b) understand the influence of photoperiod on growth and reproduction, (c) understand the potential role of seeds in population establishment, and (d) elucidate the phylogenetic relationships between the Res yellow nutsedge biotype and purple nutsedge. Tuber production per plant and tuber weight of the Res biotype were less than that of the Sus biotypes. Differences in quantitative traits, such as shoot and tuber production existed between the Res and Sus biotypes for photoperiods ranging from 12 to 16 h. Generally, photoperiods greater than 12 h increased shoot development in all yellow nutsedge biotypes, with differential responses among the biotypes. Number of tubers reached the maximum for the Res biotype at a 14-h photoperiod. Over a 90-d period, inflorescence formation was only observed in the Res biotype with maximum flowering and seed production in the 14-h photoperiod. Subsequent tests revealed up to 18% seed germination, suggesting that seed could also play a role (in addition to tubers) in the persistence and spread of the Res yellow nutsedge. Phylogenetic analysis based on ribosomal DNA internal transcribed spacer (ITS) regions and mitochondrial nad4 gene intergenic spacer sequences indicated that the Res biotype was more closely associated with Sus yellow nutsedge biotypes. Nevertheless, 100% similarity for the nad4 gene sequences between the Res yellow nutsedge biotype and a reference purple nutsedge suggests that the Res biotype is likely a result of hybridization between yellow and purple nutsedges, which perhaps explains the intermediary growth characteristics observed in the Res biotype.

In a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) rotation system, a study was conducted to determine the effects of different fertilization regimens (no fertilization, replacement of a portion of chemical fertilizer with composted pig manure, chemical fertilizer only, and straw return combined with chemical fertilizer) on the weed communities and wheat yields after 4 and 5 yr. The impact of the long-term recurrent fertilization regimen initiated in 2010 on the composition and diversity of weed communities and the impact of the components and total amount of fertilizer on wheat yields were assessed in 2014 and 2015. Totals of 19 and 16 weed species were identified in experimental wheat fields in 2014 and 2015, respectively, but the occurrence of weed species varied according to the fertilization regimen. American sloughgrass [Beckmannia syzigachne (Steud.) Fernald], water starwort [Myosoton aquaticum (L.) Moench], and lyrate hemistepta (Hemistepta lyrata Bunge.) were adapted to all fertilization treatments and were the dominant weed species in the experimental wheat fields. The greatest number of weed species were observed under the no-fertilization treatment, in which 40% of the weed community was composed of broadleaf weeds and the lowest wheat yields were obtained. With fertilizer application, the number of weed species was reduced, the height of weeds increased significantly, the density of broadleaf weeds was significantly reduced, the biodiversity indices of weed communities decreased significantly, and higher wheat yields were obtained. Only the chemical fertilizer plus composted pig manure treatment and the chemical fertilizer–only treatment increased the density of grassy weeds and the total weed community density. The treatment with chemical fertilizer only also resulted in the highest density of B. syzigachne. Rice straw return combined with chemical fertilizer yielded the lowest total weed density, which suggests that it inhibited occurrence of weeds. The different fertilizer regimens not only affected the weed species composition, distribution, and diversity, but also the weed density. Our study provides new information from a rice–wheat rotation system on the relationship between soil amendments and agricultural weed infestation.

Amitrole (3-amino-s-triazole), asulam (methyl sulfanilylcarbamate), glyphosate [N-(phosphonomethyl)glycine], and fosamine [ethyl hydrogen (aminocarbonyl)phosphonate] were effective in reducing the amount of shoot regrowth from field horsetail (Equisetum arvense L.) 3 months after treatment. The order of effectiveness was amitrole > glyphosate > asulam > fosamine. The advantage of adding surfactant to the spray formulation or applying herbicides to wet foliage was rate dependent for all herbicides except fosamine. Spray retention was increased by application to wet foliage and by the inclusion of surfactant in the formulation. Spray retention increased as spray volume and plant size increased and as plant growth became prostrate. A scanning electron microscope study of the shoot surfaces showed an abundance of silica-containing structures and the presence of epicuticular wax. Certain surfaces of the scale leaves did not have these characteristics, indicating that redistribution of spray to these areas may result in greater penetration with subsequent increases in herbicide performance.

Growers have been experimenting with cover crop termination timings to maximize weed suppression and potentially reduce herbicide inputs in soybean [Glycine max (L.) Merr.]. A field study was replicated three times from 2018 through 2021 in South Charleston, OH, to evaluate different management strategies involving a cereal rye (Secale cereale L.) cover crop. The objectives were to determine the effects of cereal rye seeding rate (0, 50, and 100 kg ha−1), management program (preplant, postplant, and delayed), and soybean residual herbicide (flumioxazin + chlorimuron ethyl and no herbicide) on cover crop, weed, and soybean parameters. The preplant program consisted of cereal rye terminated 7 d before planting (DBP) + a postemergence application. The postplant program consisted of cereal rye terminated 7 d after planting (DAP) + a postemergence application. In the delayed program, saflufenacil was applied in April and cereal rye was terminated 21 DAP, and there was no postemergence application. Giant foxtail (Setaria faberi Herrm.) density was reduced by the presence of cereal rye, averaged over other factors, regardless of seeding rate. Cereal rye seeding rate did not affect giant ragweed (Ambrosia trifida L.) density. The delayed management program was generally associated with the lowest weed density, but weed density was often similar in the postplant program. Setaria faberi density was lower in treatments that included a residual herbicide. Residual soybean herbicide use did not affect density of A. trifida. Terminating cereal rye after soybean planting resulted in increased soybean yield in 2019 and reduced yield in 2020, compared with preplant rye termination. These data suggest that adjusting the cereal rye management program may have a greater effect on weed suppression than adjustments to seeding rate. Delaying termination of cereal rye can aid in the suppression of weeds, but a comprehensive herbicide program was necessary to provide adequate (>85%) weed control.

Aspergillus niger v. T. ATC6275, proliferation was reduced by 2,4-dichlorophenoxyacetic acid (2,4-D) at 10 and 50 ppm. Picloram (4-amino-3,5,6-trichloropicolinic acid) at rates up to 50 ppm did not reduce fungus growth. A. niger degraded both 2,4-D and picloram, 2,4-D more effectively. Both herbicides were contained in the fungus mycellium.

Wild oats (Avena fatua L.), winter rye (Secale cereale L.), and volunteer winter wheat (Triticum vulgare Vill) are troublesome problems to many areas in the West. Wild oats are one of the most troublesome weeds on irrigated lands. Winter rye is a problem on dry lands planted to winter wheat. Volunteer wheat on dry lands makes it almost impossible to keep varieties pure, and consequently it is difficult to produce certified seed under these conditions. Volunteer susceptible varieties become infected with bunt and this not only causes the wheat to grade smutty, but also perpetuates the bunt organism so it can hybridize and produce new races.