Showing papers on "Phytotoxicity published in 1995"

Mechanism of action of allelochemicals in allelopathy.

Abstract: The primary mode of action has not been established for any allelopathic compound, albeit some physiological actions are known. The array of compounds cuts across many chemical classes, and it is unlikely they have a common mechanism of action. Allelochemicals active against higher plants are typically characterized as suppressing seed germination, causing injury to root growth and other meristems, or inhibiting seedling growth. A primary action on ATP production is indicated for the two quinones, juglone and sorgoleone, since they inhibit chloroplast oxygen evolution (I50 = 0.2 and 2.0 micromolar respectively) and strongly affect mitochondrial functions. The chloroplast block by sorgoleone is in the photosystem II complex. Cinnamic and benzoic acid derivatives alter membrane potential and have several physiological effects that suggest membrane perturbations are their initial site of action. Their thresholds (100 to 1000 micromolar) for inhibition of seedling growth, singly or in combinations, correlate with impairment of plant-water relationships. These phenolic compounds also alter mineral uptake, chlorophyll content, photosynthesis, carbon flow, and phytohormone activity. Phytotoxicity of many allelopathic chemicals may be from a generalized cellular disruption rather than a specific mechanism. A case study of Sorghum allelopathy suggests that inhibition of a receiving species results from the joint action of a number of allelochemicals with different cellular sites of action.

Recent research on problems in the use of urea as a nitrogen fertilizer

Abstract: Recent research on the NH3 volatilization, NO 2 - accumulation, and phytotoxicity problems encountered in the use of urea fertilizer is reviewed. This research has shown that the adverse effects of urea fertilizers on seed germination and seedling growth in soil are due to NH3 produced through hydrolysis of urea by soil urease and can be eliminated by addition of a urease inhibitor to these fertilizers. It also has shown that the leaf burn commonly observed after foliar fertilization of soybean with urea results from accumulation of toxic amounts of urea in soybean leaves rather than formation of toxic amounts of NH3 through hydrolysis of urea by leaf urease. It further showed that this leaf burn is accordingly increased rather than decreased by addition of a urease inhibitor to the urea fertilizer applied. N-(n-butyl)thiophosphoric triamide (NBPT) is the most effective compound currently available for retarding hydrolysis of urea fertilizer in soil, decreasing NH3 volatilization and NO 2 - accumulation in soils treated with urea, and eliminating the adverse effects of urea fertilizer on seed germination and seedling growth in soil. NBPT is a poor inhibitor of plant or microbial urease, but it decomposes quite rapidly in soil with formation of its oxon analog N-(n-butyl) phosphoric triamide, which is a potent inhibitor of urease activity. It is not as effective as phenylphosphorodiamidate (PPD) for retarding urea hydrolysis and ammonia volatilization in soils under waterlogged conditions, presumably because these conditions retard formation of its oxon analog. PPD is a potent inhibitor of urease activity but it decomposes quite rapidly in soils with formation of phenol, which is a relatively weak inhibitor of urease activity. Recent studies of the effects of pesticides on transformations of urea N in soil indicate that fungicides have greater potential than herbicides or insecticides for retarding hydrolysis of urea and nitrification of urea N in soil.

Sewage Sludge and Heavy Metal Effects on Nodulation and Nitrogen Fixation of Legumes

Abstract: Effects of sludge-borne heavy metals on plant growth, nodulation, and nitrogen (N 2 ) fixation of alfalfa (Medicago saliva L.), white clover (Trifolium repens L.), and red clover (Trifolium pratense L.) were examined. Plants were grown in the greenhouse in pots containing soil (Typic Paleudults) obtained from plots where heat-treated and Nu-Earth sludges were applied in 1976 and 1978, respectively. Two soil pH regimes (low and high) were examined for each of the treatments. Nitrogen fertilizer (NH 4 NO 3 ) was applied to one-half the pots and each legume was inoculated with the appropriate Rhizobium culture. Soil pH and sludge type significantly affected uptake of metals with phytotoxicity observed in the Nu-Earth, low pH soil. Nodulation was reduced, but not always completely eliminated in all low pH treatments, including the controls. Symbioses were generally ineffective in low pH treatments. In soils where pH was above 6.0, there was a significant increase in shoot weight and total shoot N with sludge addition. Plants derived significant quantities of N from soil, where sludge was applied many years ago. When pH was maintained at 6.0 or higher the results show that heavy metals in soil, and the resulting concentration in plants, had no effect on any of the parameters examined.

Metal and arsenic impacts to soils, vegetation communities and wildlife habitat in southwest montana uplands contaminated by smelter emissions: II. Laboratory phytotoxicity studies

Abstract: Vegetation communities on metal- and arsenic-contaminated uplands surrounding a smelter in southwest Montana have been eliminated or highly modified. Laboratory toxicity tests were performed using site soils from the impacted areas to determine whether the soils limit the ability of plants to establish and grow. The germination and growth of alfalfa, lettuce, and wheat in impacted area soils was compared to germination and growth of the three species in reference soils. The degree of phytotoxicity was quantified using a species-endpoint toxicity score calculated on the magnitude of difference between germination and growth of plants in impacted and reference soils. The impacted soils exhibited substantial toxicity to plants: 5% of the sites were severely phytotoxic, 55% were highly phytotoxic, 10% were moderately phytotoxic, 20% were mildly phytotoxic, and 10% were nontoxic. Root growth was consistently the most affected endpoint (18 of 20 impacted soils) and reduction in root length and mass was observed. Correlation and partial correlation analysis was used to evaluate the causes of phytotoxicity. Concentrations of As, Cu, and Zn and, to a lesser extent, Pb and Cd were found to be positively correlated with phytotoxicity.

Biomonitoring ozone phytotoxicity in eastern Spain

Abstract: High ozone (O3) levels have been recorded in eastern Spain. A project was developed to identify the areas of elevated O3 and determine if these levels were above critical concentrations for plant damage. Thus, a network of bioindicators was established in two Autonomous Communities of Spain: Catalunya (31.930 km2) and Valencia (23.305 km2) to assess O3 phytotoxicity. Three tobacco cultivars, (Bel-W3, Bel-C and Bel-B) were used during the 1994 growing season in both Regions. In Catalunya the highest O3 phytotoxicity was recorded in coastal areas, while the phytotoxicity decreased as plants were grown further in-land. A lower O3 phytotoxicity was observed in coastal sites of the Valencia Autonomous Community, compared to Catalunya, although the O3 injury was observed downwind from Valencia city in the most resistant cultivar Bel-B. The results in the Valencian Community were difficult to interpret, since plant viruses were widely distributed, not only in indicator plants, but also in commercial crops grown in the area. The analysis of O3 concentrations, meteorological parameters and visible injury at the Catalan sites showed that high relative humidity levels could favour O3 phytotoxicity. Therefore, the interactions between O3 exposure and environmental conditions on plant response should be further studied for the establishment of sound critical levels.

Surfactant effects on glyphosate efficacy

Abstract: Field and greenhouse studies were performed to examine the influence of various surfactants with glyphosate on whole plant efficacy. Relationships were examined between glyphosate phytotoxicity and surfactant properties, including ionic form, degree of ethoxylation, and hydrophobe composition. Cationic tertiary amine surfactants enhanced glyphosate performance in both field and greenhouse studies. Nonionic allinol and octoxynol surfactants were not effective in combination with glyphosate. In field studies, glyphosate efficacy increased with increasing surfactant ethylene oxide (EO) content. Soybean and velvetleaf responded similarly to glyphosate-surfactant spray applications, as both demonstrated significant linear and quadratic relationships between increasing surfactant ethoxylation and phytotoxicity, while common lambsquarters showed a significant linear relationship only. Cationic surfactants were evaluated in the greenhouse and a significant quadratic regression of glyphosate phytotoxicity to common lambsquarters on increasing surfactant ethoxylation indicated an optimum surfactant EO content of about 10 moles. Both tertiary and quaternary ethoxylated fatty amines were effective with glyphosate in decreasing common lambsquarters' fresh weight. Fatty amine hydrophobe composition did not correlate with glyphosate phytotoxicity to common lambsquarters. Nomenclature: Glyphosate, N-(phosphonomethyl)glycine; common lambsquarters, Chenopodium album L. # 3 CHEAL; velvetleaf, Abutilon theophrasti Medicus # ABUTH; soybean, Glycine max (L.) Merr. 'Elgin.'

The effect of salinity on early seedling growth of seeds of three wheat (Triticum aestivum L.) cultivars

Abstract: We studied the effects of three salinity levels (50, 100 and 150 mM NaCl) on the early seedling growth of three wheat (Triticum aestivum L.) cultivars of Albanian origin characterized by different sensitivities to salt. Sodium accumulation was similar in seedlings of different cultivars and, in general, Na+ was confined to the root. Chloride accumulated at high levels in both the root and the shoot but least so in Daity. No appreciable differences were observed in K+ content. The most salt-tolerant cultivar showed a higher capacity for osmoregulation than the other two cultivars. Key words: Ion regulation, ion toxicity, osmoregulation, salinity, Triticum aestivum

Isomerization and peroxidizing phytotoxicity of thiadiazolidine-thione compounds

Abstract: Eight 5-arylimino-3,4-tetramethylene-1,3,4-thiadiazolidine-2-thiones and eight 4-aryl-1,2- tetramethylene-1,2,4-triazolidine-3,5-dithiones were synthesized and their phytotoxic activities were investigated using sawa millet (Echinochloa utilis), green microalgae (Scenedesmus acutus) and protoporphyrinogen-IX oxidase isolated from etiolated corn (Zea mays) seedlings. 5-Arylimino-3,4-tetramethylene-1,3,4-thiadiazolidine-2-thiones showed strong phytotoxic activities and the same herbicidal mode of action as known for peroxidizing herbicides. 5-Arylimino-3,4-tetramethylene-1,3,4-thiadiazolidine-2-thiones were not or very little converted into 4-aryl-1,2-tetram ethylene-1,2,4-triazolidine-3,5-dithiones either with E. utilis seedlings present for 7 days, with S. acutus cells, or using glutathione 5-transferase (GST) and glutathione (GSH). The phytotoxic activities of 4-aryl-1,2-tetram ethylene-1,2,4-triazolidine- 3,5-dithiones were stronger than those of 5-arylimino-3,4-tetram ethylene-1,3,4-thiadiazolidine- 2-thiones [cf. Sato, Y., et al., Z. Naturforsch. 49c, 49-56 (1994)].

Spray deposition of fenoxaprop and imazamethabenz on wild oat (Avena fatua) as influenced by environmental factors

Abstract: The effect of soil moisture, temperature, and light intensity on the spray deposition of fenoxaprop and imazamethabenz applied to wild oat plants was examined by using fluorescent tracer dye. Based on either biomass or total leaf area, the apparent deposition of the two herbicides di- minished in the following order: shading > low temperature ? drought ? "optimum" > high temperature. The enhanced phytotoxicity of both herbicides under shading could be associated with increased spray deposition; and reduced fenoxaprop phytotoxicity under high temperature stress could be related to reduced deposition. Changes in spray deposition were attributed mainly to differences in herbicide interception due to altered plant morphology. Reduced re- tention for both herbicides was exhibited only in the plants grown at high temperature. Under "optimum" conditions, fenoxaprop phytotoxicity was directly associated with leaf orientation and thus with the proportion of projected leaf area at the time of herbicide spraying. Given similar appli- cation conditions, spray deposition of fenoxaprop and imazamethabenz on wild oat could be estimated by determin- ing the ratio of the projected leaf area, as measured by an image analyzer, to the total leaf area. Nomenclature: Fenoxaprop, (?)-2-(4-((6-chloro-2-benzoxazolyl)oxy)phe- noxy)propanoic acid; imazamethabenz, (?)-2-(4,5-dihydro- 4-methyl-4-(1-methylethyl)-5-oxo-lH-imidazol-2-yl)-4 (and 5)-methylbenzoic acid (3:2); wild oat, Avena fatua L. #3 AVEFA. Additional index words. Retention, leaf orientation, drought, shading, imidazolinones, aryloxyphenoxypropionic acids, AVEFA.

Phytotoxicity studies of benzo [a] pyrene with Lactuca sativa*

Abstract: In this project the effect of increasing concentration of benzo[a] pyrene (0.1, 1, 5, 10, 50 and 100 mg/L), the interaction of sodium humate (10, 100 and 500 mg/L) and BaP (0.1–10 mg/L) and the effect of environmental acidity (pH 4.5, 6.5 and 8.5) on the growth of the root and the hypocotyl of lettuce in the dark and in the light was studied. The results obtained document the fact that increasing BaP concentration (0.1–10 mg/L) stimulated the length of both root and hypocotyl of plants growing in the dark as well as in light. Significant inhibition of growth was demonstrated in plants cultivated in BaP of 100 mg/L concentration. Significantly lower lettuce root and hypocotyl growth in comparison with stimulating effects of BaP was recorded in the application of all combinations of BaP with sodium humate. In neutral and alkaline environments (pH 6.5 and 8.5) no significant effect of pH was found on the action of BaP. In an acid environment (pH 4.5) a synergic effect of environmental acidity and BaP toxicit...

Household Detergent on Tomato: Phytotoxicity and Toxicity to Silverleaf Whitefly

Abstract: Household detergents were evaluated in field studies on fresh-market tomato (Lycopersicon esculentum Mill.) for insecticidal and phytotoxic effects. Laboratory bioassays were used to examine the toxicity of a household liquid dish detergent on small nymphs of silverleaf whitefly, Bemisia argentifolii Bellows and Perring. The detergents tested proved to be more toxic to whitefly nymphs than the commercial insecticidal soap. Detergent treatments were applied to tomato with a commercial high pressure hydraulic sprayer at 0%, 1%, 2%, 4%, and 8% (by volume) initially and at 0%, 0.25%, 0.5%, 1.0%, and 2.0% (by volume) in subsequent tests. As detergent rate, frequency of application, or both increased, plant dry weight accumulation and fruit yield decreased. Applying detergent also increased time to fruit maturity. A once-a-week application of 0.25% to 0.5% detergent initially applied 2 weeks after transplanting alleviated phytotoxicity and yield reduction problems.

Bush bean (Phaseolus vulgaris L) leaf injury, photosynthesis and stomatal functions under elevated ozone levels

Abstract: Three bush bean cultivars (Lit, Groffy and Stella) were grown under four levels of ozone exposure (ambient air+50 ppb O3 ambient air+25 ppb O3, ambient air and charcoal filtered air) in open- top chambers. Number and leaf injury statistics showed significant reduction in the number of healthy leaves as the level of O3 increased. The area based leaf injury percentages of the cvs. Lit, Groffy and Stella were 69.8, 57.9 and 71.1% at the highest O3 level, 24.1, 19.6 and 30.3% at the 2nd highest O3 level, and 4.5, 0.7 and 5.6% at the ambient air, respectively. The plants grown in the filtered air revealed no injury symptoms. The stomatal conductances were found to decrease gradually in each cultivar as the O3 level increased. At the highest O3 level, Chlorophyll fluorescence measurements on the 2nd leaf from the top on 24th day of exposure resulted in significantly the highest Fv/Fm values, the lowest f0 and the highest Fm values whereas the 4th leaf showed the smallest Fm and correspondingly the smallest Fv/Fm values. This is an indication of photosystem II damage after accumulation of a high ozone dose in the 4th leaf. The photosynthetic rate of the 2nd leaf measured on 30th day of exposure was comparatively higher at the highest exposure but the data taken from the same leaf on 40th day of exposure showed significantly lower photosynthetic rate than the plants in ambient air. Both chlorophyll fluorescence and photosynthetic measurements indicated that ozone stressed leaves experience a stimulation of photosynthesis (possibly due to increased assimilate demand) prior to irreversible damage. Bush bean leaves need to accumulate a critical ozone dose(an AOT40 of presumably > 18 ppm-h) for reduction of the photosynthetic capacitys.

Residual effect of composted olive oil mill sludge on plant growth

Abstract: Summary: Residual effect of a composted olive oil milI sludge on growth and mineral composition of taH fescue (Festuca arundinacea) was studied. Results were compared with those obtained for a mineral ferulizer treatment and a control. Compost and inorganic fertilizer had been previously applied to two different soils at two rates for five years. The compost did not display the phytotoxicity of olive oil milI wastewater, and produced, at high doses, the highest yield and concentrations of P and K in tissue, while decreasing Na, Mn, and Zn a'isimilability.

Plant conditioner comprising vitamin E, and its use

Abstract: There is described a plant conditioner comprising vitamin E, surfactants and, if appropriate, other formulation auxiliaries in a non-phytotoxic carrier suitable for use in plants, the plant conditioner being characterised in that it comprises non-ionic surfactants as surfactants and in that the carrier is an organic or organic/aqueous solvent system. Its use for reducing or inhibiting phytotoxicity symptoms on plants caused by agrochemicals and/or environmental toxins and for increasing the selectivity of herbicides producing oxygen free-radicals is also described. The plant conditioner according to the invention allows phytotoxicity caused by agrochemicals and/or environmental toxins to be reduced considerably and, in some cases, even to be prevented.

Herbicidal compositions of 4-benzoylisoxazole and antidotes therefor

Abstract: Herbicidal compositions containing 4-benzoylisoxazole compounds and antidotal compounds therefor to reduce injury to various crops, particularly corn, from the phytotoxic effects of 4-benzoylisoxazole herbicides when used alone or in combination with additional pesticidally active ingredients. Methods for reducing phytotoxicity or injury to crop plants, particularly corn crops, due to 4-benzoylisoxazole herbicides are also described.

The efficacy and phytotoxicity of Xenorhabdus bovienii A2 metabolites as agricultural fungicides

Abstract: Xenorhabdus bovienii A2 is a bacterial symbiont of Steinemema carpocapsae, which is an entomopathogenic nematode currently used to manage some insect pests. This bacterium produces a broad spectrum of antimicrobial metabolites. Experiments were done to test the antimycotic activity and phytotoxicity of the antimicrobial metabolites of X. bovienii on selected plant pathogenic fungi on Petri plates and plants, and thereby demonstrating the potential of these substances as agricultural fungicides. Three fractions, organic (ABT001), 'whole' (ABT002), and aqueous (ABT003). obtained from the supernatant of 96-h-old X. bovienii culture in tryptic soy broth, were tested. ABTOOl at 0.1 mg/ml was fungicidal against Phytophthora infestans on rye agar but only partially inhibited Pythium ultimum and Rhizoctonia solani on 0.39 % PDA in Petri plate tests. Both ABT002 and ABTOO3 were fungicidal against P. infestans at 1.0 mg/ml but not against P. ultimum and R. solani. In potted plant tests, ABTOOl was applied to the. foliage of 4to 5-week-old potato plants (cv. Norchip) and potted grass (mixture of 40 % ryegrass, 40 % fescue and 20 % bluegrass) as a protectant spray at concentrations of 5.0 and 10.0 mg /d (wlv), and 2.0, 10.0 and 20.0 mdml (wlv), respectively. ABT002 was tested on only potato plants at 10.0 and 50.0 mdml (wlv). Against P. ultimum, ABTOOl was coated on bush bean seeds (cv. Venture-Blue Lake) at rates of 0.3, 1.5 and 7.5 mg/g of seed (w/w) with diatomaceous earth and methyl cellulose. When potted potato plants were assessed 7 d after inoculation, the 10.0 mg/ml ABTOOl and 50.0 mg/ml ABTOO2 treatments significantly (P 0.05) from that of the 10.0 mg/ml (w/v) chlorothalonil treatment. At lower concentrations, 5.0 mg /d ABT001 and 10.0 mgftnl ABT002 significantly (P < 0.05) decreased late blight infection to 24.0 and 58.0 %, respectively and reduced the size of the blighted lesions on inoculated leaflets when compared with those of the controls. ABTOOl treatments provided incomplete protection against R. solani and P. ultimum on potted grass and bush bean seeds, respectively. Phytotoxicity was observed on all test plants treated with ABT001, and the phytotoxic damage increased proportionally with increasing concentrations. The visible phytotoxic responses on potato plants treated with up to 10.0 m g h l ABTOOl or 50.0 m g h l ABTOO2 were not permanent as treated plants grew away fiom the phytotoxic damage. The selectivity of ABTOOl against the three test fungi, its phytotoxic properties and the potential of the active metabolites fiom X bovienii culture supernatant in future fungal disease control

Forecasting agrobiological properties of wheat straw with different additives—multiple regression models including chemical parameters

Abstract: The agrobiological properties of 37 composts prepared from wheat straw with a series of organic or mineral additives have been determined through standard chemical analyses and greenhouse experiments with soils of different carbonate content and in the presence, or absence of mineral fertilization. Plant yield on soils treated with the composts was studied in successive stages of development of rye grass (Lolium rigidum), showing significant differences that paralleled the values of a limited number of compost parameters. Under greenhouse conditions and in the presence of mineral supply, the least matured composts led to improved plant yield only in the early harvests, decreasing thereafter which points to a behavior typical for the microbial immobilization of the additional nutrients. The germination (phytotoxicity) index was found poorly correlated with the yield in the different soils, whereas the N and lignin contents provided the most significant information, the results suggesting no cause‐...

Weed Control in Puddled Seeded Rice in Dry Season in Coastal Orissa

Abstract: An experiment was carried out during dry seasons of 1993 and 1994 at Cuttack (coastal alluvial soil) to evaluate herbicides for controlling weeds in puddle seeded rice. Among herbicides/herbicide combination sanilofos alone and in combination with 2,4-DEE showed higher degree of phytotoxicity on rice seedlings, while granular formulations of anilofos did not cause any phytotoxicity during 1993. During second year pre-emergence application of anilofos (0.4 and 0.6 kg/ha), anilofos +2,4 DEE (0.3 +0.42 kg/ha), butachlor (1.0 and 1.5 kg/ha) and pendimethalin (1.0 and 1.5 kg/ha) gave comparable yield to weed free treatment The weed control efficiency of these herbicides was upto 90.0 per cent. Application of anilofos + 2,4-DEE at both rates showed slight phytotoxicity during 1994.

Mixtures of Olive Pomace with Different Nitrogen Sources for the Control of Meloidogyne spp. on Tomato 1

Abstract: R. RODR~GUEZ-K.&BANA, 2 V. ESTAON, 3 J. PINOCHET, 3 AND 0. MARFJ~ 4 Abstract: The efficacy of mixtures of dry olive (Olea europea) pomace with biuret, guanidine, and melamine for control of root-knot nematodes (Meloidogyne spp.) on tomato (Lycopersicon esculentum) was studied in greenhouse experiments. Olive pomace (OP) applied pre-plant at 10 g/kg soil was phytotoxic. Mixtures of OP (10 g/kg soil) with biuret or guanidine at 200-300 mg/kg soil reduced or eliminated the phytotoxic effect, controlled root-knot nematodes, and increased soil esterase activity indicative of microbial activity. The addition of biuret or guanidine without OP to soil at rates <300 mg/kg soil did not control root-knot nematodes. Melamine applied at 100-400 mg/kg soil was phytotoxic as were mixtures of melamine with OP. Treatment of OP with anhydrous ammonia increased N content of the material. In another greenhouse experiment, NHs-treated OP added to soil was not phytotoxic to tomato, suppressed root-knot nematodes, and increased soil esterase activity. Greenhouse and microplot experiments with OP plus chicken litter demonstrated the effi- cacy of these combination amendments to control root-knot nematodes and increase tomato yields in Meloidogyne-infested soil. Olive (Olea europaea) pomace (OP), a waste product from oil extraction pro- cesses, is produced in large quantities in Spain, Italy, and other Mediterranean countries. Ecologically appropriate dis- posal of this material may be a problem because its uses as fodder and as a cattle feed additive are limited (10). Olive pom- ace is suppressive to root-knot nematodes (Meloidogyne spp.) when incorporated in soil (15). It contains propionic and other low-molecular-we ight monocarboxylic ac- ids, which are toxic to many plant species (5,11,12). Phytotoxicity of OP amend- ments to soil is reduced or eliminated when the material is mixed with urea. The OP-urea mixture has a lower C:N ratio, which stimulates microbial degradation of the phytotoxic components of OP and en-

Phytotoxicity Evaluation of an Insecticidal Soap and Horticultural Oil on Six Turfgrass Species

Abstract: Phytotoxic effects of a insecticidal soap (Safer Insecticide Concentrate®) and petroleum-based horticultural oil (Sunspray Ultra-Fine Spray Oil®) were evaluated on four cool-season and two warm-season turfgrass species under cool and moist, and hot and dry environmental conditions. Ambient temperature, relative humidity, and water deficit level of the turfgrass had little observed effect on levels of phytotoxicity. Little or no foliar injury was observed under any environmental conditions following application of insecticidal soap or 1% and 3% horticultural oil on any turfgrass species. In most instances 5% horticultural oil initially caused slight to moderate foliar discoloration, whereas 10% horticultural oil resulted in moderate to substantial foliar discoloration depending on the turfgrass species. Zoysiagrass and creeping bentgrass were the most susceptible species to higher concentrations of horticultural oil. Phytotoxicity was relatively brief even in these more susceptible grasses, however, and th...

Effect of Sodium Bisulfate on the Phytotoxicity, Retention, Foliar Uptake, and Translocation of Imazamethabenz on Wild Oats (Avena fatua L.)

Abstract: Studies determined the effect of sodium bisulfate (NaHSO4) on the phytotoxicity, retention, uptake, and translocation of the suspension concentrate formulation of imazamethabenz in wild oats. NaHSO4 completely solu- bilized this herbicide formulation when added in an equimo- lar concentration and did not affect herbicidal activity at NaHSO4 concentrations below 28 mM when used in a carrier volume of 100 L ha-'. NaHSO4 improved phytotoxicity at a carrier volume of 33 L ha-'. NaHSO4 at 28 mM increased the efficacy of imazamethabenz applied as individual drops on growth chamber-grown wild oats. The herbicide retention was not changed but foliar absorption and acropetal translo- cation were increased, while basipetal translocation was decreased. The increase in phytotoxicity of imazamethabenz with NaHSO4 was related to absorption of imazametha- benz by the target plants. Nomenclature: Imazametha- benz, (?)-2-(4,5-dihydro4-methyl-4-(1-methylethyl)-5-oxo- 1H-inmidazol-2-yl)-4(and 5)-methylbenzoic acid (3:2); wild oats, Avena fatua L. #3 AVEFA. Additional index words. Sodium bisulfate, phytotoxicity, re- tention, uptake, translocation, AVEFA.

Carpeted Roller Application of Herbicides for Larkspur (Delphinium spp.) Control

Abstract: A carpeted roller applicator and broadcast sprayer were compared for application of glyphosate, metsulfuron, and picloram to control duncecap and tall larkspur on mountain range sites in southern Idaho and central Utah, respectively. Glyphosate was the most effective herbicide, controlling 96% of both larkspur species when applied by the sprayer and 78% when applied by the roller. There was no difference in larkspur control between application methods using metsulfuron or picloram. Application of herbicides by the carpeted roller was less detrimental to forbs compared to the sprayer, and the roller application of glyphosate did not reduce grass cover. Grass cover doubled following treatments with picloram and metsulfuron. Nomenclature: Glyphosate, N-(phosphonomethyl)glycine; metsulfuron, 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]benzoic acid; picloram, 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid; duncecap larkspur, Delphinium occidentale S. Wats # 3 DELOC; tall larkspur, Delphinium barbeyi (L.) Huth # DELBA.