Showing papers on "Phytotoxicity published in 1978"

Production and phytotoxicity of acetic acid in anaerobic soils containing plant residues

Abstract: Acetic acid accumulated in slurries of peat, loam and clay soils mixed with wheat (Triticum aestivum) straw and reduced the growth of roots of young barley (Hordeum vulgare) plants. Straw from wheat, barley, oat (Avena sativa) and rape (Brassica napus) and decaying rhizomes of couch grass (Agropyron repens) mixed with slurries of the loam soil, had the same effect. The breakdown of acetic acid was slow in flooded soil and the maximum accumulation took place under these conditions; by contrast aeration of the soil prevented its accumulation. Solutions in which straw had fermented produced inhibitory effects on seed germination and the growth of seedlings in atmospheres containing between 3 and 21% O2. The phytotoxicity could be mitigated by dusting the seeds with powdered chalk.

Cercosporin, a phytotoxin from Cercospora spp

Abstract: The production, in vitro and in vivo , of a red biologically active substance, cercosporin, by 12 isolates of Cercospora spp. from 10 hosts in Nigeria is reported. Optimum production in culture occurred on PDA at 22·5 °C under 12 h alternating periods of light and darkness. The substance was extracted in acetone and purified by thin-layer chromatography. It inhibited the growth of bacteria at 2·5 μg/ml but had no effect on fungi, even at 100 μg/ml. The phytotoxicity of the compound was established on Ricinus communis , Glycine max , Nicotiana tabacum , Phaseolus vulgaris and Vigna unguiculata . Although the phytotoxicity was not host-specific, the minimum dose that induced symptoms on the different hosts varied. The possible role of the compound in pathogenicity, and the taxonomic significance of its production in the genus Cercospora , is discussed.

Phytotoxicity Associated with Residue Management1

Abstract: In many parts of the United States and the world, phytotoxicity associated with crop residues is a potential problem facing conservation tillage systems. Residues left on or near the soil surface frequently reduce growth and yields of the next crop as compared with those when residues are removed or when conventional tillage is used. Cereals seem particularly susceptible. Wheat (Triticum aestivum L.) is mentioned most often, probably because of its world-wide economic importance (Cochran et aI., 1977; Davidson & Santelman, 1973; Kimber, 1967; McCalla & Duley, 1949; Phillips et aI., 1976). McCalla and Army (1961) indicated that the yield reduction problem with stubble-mulch tillage was likely residue related because wheat yields were decreased more frequently as annual rainfall increased. While the poor growth resembles nitrogen deficiency, it is not corrected by N applications (Davidson & Santelmann, 1973; Duly, 1960; Kimber, 1967). Reduced yields have been attributed to toxic compounds leached from crop residues and! or to microbial production of toxic compounds

Foliar fertilization method and composition

Abstract: Aqueous urea solutions particularly suited for foliar fertilization are disclosed. They are characterized by low phytotoxicity, low corrosivity, and improved toxicity stability and comprise urea nitrogen and between about 0.005 and about 0.1 molar equivalents per mole of urea of a pH buffer having a buffering point between about 6 and about 7.6. Also provided are aqueous urea solutions suitable for foliar application containing mineral or organic acids, or both, in the presence or absence of a pH buffer having pH values between about 6 and 7.6. Either solution is foliarly applied at substantially non-toxic rates of at least about 10 pounds of nitrogen per acre.

Effect of soil organic matter on the phytotoxicity of soil-applied herbicides — field studies

Abstract: Field trials were conducted over 3 years to study the phytotoxicity of 5 soil-applied herbicides on 13 Horotiu sandy loam soils with 8.0–19.3% organic matter. Oats and soya beans were grown as indicator plants to test the activity of herbicides. Phytotoxicity of all five herbicides was highly and negatively correlated with the soil organic matter content. Two to three times as much herbicide was required for similar weed control in the highest organic matter soil compared with the soil lowest in organic matter. In general, there was an inverse relationship between herbicide water solubility and its inactivation by organic matter. The activity of trifluralin was most affected by changes in the organic matter content and terbacil was least sensitive to such variations. Regression equations for the amount of herbicide required for 80% weed control in oats and soya beans were computed for each herbicide. The actual rate of herbicide required at various organic matter levels varied depending on the te...

Temperature Effect of Phytotoxicity of Soil-Applied Herbicides

Abstract: Experiments were conducted in controlled environmental chambers to determine the influence of temperature on the phytotoxicity of seven soil-applied herbicides. Diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid} soil incorporated or surface applied, was more toxic to wild oat (Avena fatua L.) shoots at 10 and 17 C than at 24 C. Efficacy of diclofop was enhanced with soil incorporation. Diclofop toxicity to wild oat roots was not influenced by a change in temperature. EPTC (S-ethyl dipropylthiocarbamate) stimulated sugarbeet (Beta vulgaris L. ‘American Crystal Hybrid B’) shoot dry weight production at 10 C and caused dry weight reduction at 24 C. Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] toxicity to barley (Hordeum vulgare L. ‘Larker’) and alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] toxicity to oats (Avena sativa L. ‘Chief’) increased with increased temperature from 10 to 17 C. Temperatures within the range of 10 to 24 C did not affect trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) toxicity to barley or BAY-5653 [N-(2-benzothiazolyl)-N-methylurea] or chloamben (3-amino-2,5-dichlorobenzoic acid) toxicity to oats.

Excess trace metal effects on cotton: 3. Chromium and lithium in solution culture

Abstract: Two cultivars of cotton (Gossypium spp) were grown in solution culture in a glasshouse to determine phytotoxicity effects of excesses of Cr and Li. The 10‐4 M Cr2(SO4)3 resulted in leaf yield reduction of 83% and in leaf, stem and root concentrations respectively of 22, 15, and 410 μg Cr/g with the Acala SJ‐2 cv. With the Giza 68 cv. the same level of Cr resulted in leaf yield reduction of 88% and in 19, 47, and 450 μg Cr/g for leaf, stem and roots respectively. The Cr resulted in many mineral interactions. The 10‐4M Li2SO4 resulted in very little if any yield reductions in either cv. Plant Li concentrations were 40, 8, and 10 and 45, 10 and 5 for leaf, stem and root for Acala SJ‐2 and Giza 68 respectively. Both cultivars tolerated Li equally well.

Residues of diuron and phytotoxic degradation products in aquatic situations. I. Analytical methods for soil and water

Abstract: Thin-layer and gas-liquid chromatography, ultraviolet analysis and bioassay with Chlorella spp. have been used to investigate the pathway of degradation of diuron to phytotoxic derivatives when diuron was used as a soil-residual herbicide in irrigation canals. Observations suggest that 1-(3,4-dichlorophenyl)-3-methylurea and 1-(3,4-dichlorophenyl)urea make a contribution to total residues equivalent to a maximum of about 40 and 55%, respectively, of diuron concentrations. Application of a phyto-toxicity rating suggests that in this environment, measurement of diuron specifically would underestimate the total phytotoxicity of residues by a maximum of about 7%.

PHYTOTOXICITY OF SOIL-APPLIED DICHLORFOP METHYL AND ITS EFFECT ON UPTAKE OF 45Ca IN WILD OATS, BARLEY AND WHEAT

Abstract: The effect of placement of dichlorfop methyl 2[4-(2,4-dichlorphenoxy)-phenoxy propionic acid methyl ester] in the soil at the shoot and root zones of wild oats (Avena fatua L.), barley (Hordeum vulgare L. Conquest) and wheat (Triticum vulgare L. Thatcher) on plant growth and uptake of 45Ca was investigated. Dichlorfop methyl was more toxic to the roots and aerial plant growth via root exposure than shoot exposure. Wild oats was most sensitive, followed by barley and wheat. Severe root inhibition caused by dichlorfop methyl was associated with decreased uptake of 45Ca from the root zone. Root-applied dichlorfop methyl enhanced adventitious root development in the shoots of wild oats and barley resulting in a 50% and a 127% increase in shoot uptake of 45Ca, respectively. Shoot-applied dichlorfop methyl strongly inhibited adventitious root formation with a resultant decrease in 45Ca uptake of 100 and 86%, respectively, from the shoot zone. In wheat, neither adventitious roots nor uptake of 45Ca from the shoo...

Excess trace metal effects on cotton: 6. Nickel and cadmium in yolo loam soil

Abstract: Two cultivars of cotton (Gossypium spp.) were grown in Yolo loam soil in a glasshouse to determine phytotoxicity effects of excesses of Ni and Cd. A 200 μg/g level of Ni in soil reduced yield by 60% in Acala SJ‐2 and by 83% in Giza 45. The leaf Ni concentrations, respectively, were 146 and 165 μg/g‐ The 300 μg/g level of Cd decreased leaf yields by 60% and 75% for the two cultivars, respectively. Leaf concentrations of Cd, respectively, were 43 and 63 μg/g. There was a stem to leaf gradient of Cd for all cases. High Cd did not depress Mn concentrations in plants . as in other species but there were many mineral element interactions.

Agricultural spray oils containing zinc dialkyldithiophosphates

Abstract: The phytotoxicity of conventional agricultural spray oils is reduced by the incorporation therein of between 0.10 and 0.25 weight/volume percent thereof of at least one zinc dialkyldithiophosphate wherein the alkyl group ranges from C 3 to C 8 . The additive also provides zinc and phosphorus to the plants treated with such oils.

Excess trace metal effects on cotton. 1. Copper, zinc, cobalt and manganese in solution culture

Abstract: Two cultivars of cotton (Gossypium spp) were grown in solution culture in a glasshouse to determine phytotoxicity effects of excesses of Cu, Zn, Co and Mn. Leaf yields of Acala SJ‐2 were depressed 76% by 10‐4 M CuSO4, 86% by 5×10‐4 M ZnSO4, 82% by 10‐4 M CoSO4, and 20% by 10‐3 M MnSO4. Leaf concentrations associated with these depressions were (μg/g) 110 Cu, 198 Zn, 180 Co, and 5470 Mn respectively. Plants were tolerant of in μg/g of about 15 Cu, 106 Zn, 69 Co, and 1830 Mn. Leaf yields of Giza 70 were depressed 91% by 10‐4 M CuSO4, 88% by 5×10‐4 M ZnSO4, 87% by 10‐4 M CoSO4, and 68% by 10‐3 M MnSO4. This cv. was less tolerant of Mn than was Acala SJ‐2. Leaf metal concentrations at these application rates were (μg/g) 65 Cu, 243 Zn, 255 Co, and 6550 Mn respectively. In general roots were higher in these four metals than stems and leaves. There was no strong gradient from stems to leaves. Many nutrient interactions were observed as result of excesses of the four trace metals.

Excess trace metal effects on cotton: 5. Nickel and cadmium in solution culture

Abstract: Two cultivars of cotton (Gossypium spp.) were grown in solution culture in a glasshouse to determine phytotoxicity effects of excesses of Ni and Cd. Leaf yield was depressed 94% by 10‐4 M NiSO4(with 198μg Ni/g leaf) in Acala SJ‐2 and 93% (with 167μg Ni/g) in Plma PS‐5. The Ni gradient was roots > stems > leaves in both cultivars. At 10‐5 M, CdSO4 gave more phytotoxicity than NiSO4. The 10‐4 M CdSO4 resulted in about the same amount of phytotoxicity as did the Ni for both cultivars. The Pima PS‐5 plant parts, however, contained less Cd than did the Acala SJ‐2 at the highest Cd concentration. At 10‐5 M CdSO4 the reverse held in leaves and stems. Interactions held for both metals but the inverse effect between Cd and Mn was less pronounced than for other species. Many other interactions were present.

Influence of phosphorus on the phytotoxicity of alachlor

Abstract: The effects of different levels of phosphorus on the initial and residual activity of alachlor (2-chloro-2, 6-diethyl-N-methoxymethylacetanilide) were studied in glasshouse experiments using German millet (Setaria italica (L.) Beauv.), a species susceptible to alachlor. Results showed that the initial phytotoxicity of alachlor decreased with the increasing rates of phosphorus. As the concentration of the herbicide was increased, higher levels of phosphorus were required to alter its phytotoxicity. The phosphorus concentration in plant tops increased with increments in the phosphorus level of the soil and was unaffected by alachlor at low rates. At high concentrations of the herbicide the phosphorus level of some plant shoots increased significantly, although such increases tended to vary with the size of the shoot. Bioassay data showed no significant influence of phosphorus additions to the soil on the residual activity of alachlor.

Agricultural and horticultural bactericide

Abstract: PURPOSE:To provide an agricultural and horticultural bactericide free from toxicity, phytotoxicity, and environmental pollution, effective against rice blast, bacterial leaf blight, powdery mildew of cucumber, graymold, etc., containing a cyclic dipeptide composed of alpha-amino acids as an effective component.

Controlling agents for plant pests

Abstract: PURPOSE:To prepare fungicides containing fatly acid nickel salt as an active constituent, having contorlling effects against plant pests such as bacilliary plant pests (e.g. bacterial leaf blight on rice plants and bacterial soft rot on Chinese cabbages) and fungous plant pests (e.g. blast on rice plants and gray mold on cucumbers) and no phytotoxicity.