Influence of Propazine and Chlorthal Dimethyl on Mycorrhizal Development in Pinus radiata Seedlings

1990 ◽  
Vol 38 (4) ◽  
pp. 341 ◽  
Author(s):  
GC Marks ◽  
SL Becker
Keyword(s):  
Side Effects ◽  
Pinus Radiata ◽  
Shoot Growth ◽  
Surface Soil ◽  
Field Application ◽  
Stages Of Growth ◽  
Unusual Association ◽  
Application Rates ◽  
Mycorrhizal Development ◽  
Thick Mantle

In an investigation into the side effects of herbicides on mycorrhizal formation in Pinus radiata nurseries, propazine and chlorthal dimethyl were added at concentrations that approximated to normal (2.20 and 1.88 g a.I-1L) and half-normal (1.10 and 0.94 g a.i.-1L) field application rates respectively to P. Radiata seedlings growing in terra cotta pots. A humus-rich, surface soil from a 40-year-old P. radiata plantation was used as mycorrhizal inoculum. Root length, mycorrhizal numbers and type, and seedling growth were assessed and a histological examination of bulk mycorrhizal samples was carried out. Propazine applied at both dosage rates and chlorthal dimethyl at the higher rate significantly sup- pressed root growth during the first 3 months and mycorrhizal formation during both the early and later stages of growth. However, neither herbicide affected shoot growth after 3 months and both increased shoot growth at the end of 6 months. Two mycorrhizal types were identified, a white-coloured, heavily dichotomised ectomycorrhiza with a thick mantle and a reddish-coloured, weakly dichotomous ectendomycorrhiza. The roots of chlorthal dimethyl treated seedlings strongly suppressed intracellular penetration in the ectendomycorrhiza, producing an unusual association with only a Hartig net, which was similar to that seen in senescing associations and some long roots of conifers. The ratio of white to red mycorrhizal numbers was highest in the untreated controls and was reduced by both herbicides. Both herbicides appeared to effect mycorrhizal formation through their influence on root morpho- genesis and host physiology.

Effects of asulam spraying on non-target ferns

2005 ◽  
Vol 83 (12) ◽  
pp. 1622-1629 ◽  
Author(s):  
J.K. Rowntree ◽  
E. Sheffield
Keyword(s):  
Experimental Evidence ◽  
Application Rate ◽  
Field Application ◽  
Pteridium Aquilinum ◽  
Buffer Zones ◽  
Application Rates ◽  
Highly Sensitive ◽  
Fern Species ◽  
Aerial Spraying ◽  
Work Supports

The systemic herbicide asulam is used extensively to control the weedy fern bracken ( Pteridium aquilinum (L.) Kuhn). Other ferns were thought to be highly sensitive to asulam exposure, but there has been a dearth of experimental evidence. Eight fern species were exposed to asulam spray at three different application rates or a control of water. Asulam was applied at the recommended field application rate for bracken clearance, and at two further rates corresponding to 10 and 50 m downwind of an aerial spray event. Damage was assessed over two seasons. All ferns tested were severely damaged by exposure to the highest application rate, but sensitivity varied between species. Maximum damage occurred 1 year after spraying, and limited signs of recovery could be seen by the second season. The effects of adding the adjuvant Agral® to applications of asulam were tested on the threatened pteridophyte Pilularia globulifera L. No damage additional to that caused by exposure to asulam was observed. This work supports the view that 50 m buffer zones are sufficient to protect sensitive ferns from the effects of aerial spraying with asulam, provided that drift-reducing nozzles are used and the manufacturer’s application guidelines are observed.

Plant and animal constraints to voluntary feed intake associated with fibre characteristics and particle breakdown and passage in ruminants

1996 ◽  
Vol 47 (2) ◽  
pp. 199 ◽  
Author(s):  
JR Wilson ◽  
PM Kennedy
Keyword(s):  
Organic Matter ◽  
Dry Matter ◽  
Shoot Growth ◽  
Surface Soil ◽  
Clay Soil ◽  
Grass Species ◽  
Soil Nitrate ◽  
The Sun ◽  
N Yield ◽  
Organic Matter Breakdown

Effects of artificial shading to 50% sunlight of nitrogen (N) limited tropical pastures of different grass species on a high (clay loam) and low (granitic loam) fertility soil type were evaluated in a semi-arid. subtropical environment over 3 years. The hypothesis was tested that shade can stimulate shoot growth by providing a modified environment more conducive to organic matter breakdown leading to increased mineralisation and availability of soil N, and the ability of tropical grasses to take advantage of this effect was examined. Unfertilised pastures of green panic (Panicum maximum var. trichoglume), buffel (Cenchrus ciliaris). rhodes (Chloris gayana), and speargrass (Heteropogon contortus) in full sun or shaded by sarlon cloth were sampled on 9 occasions. Additional green panic plots on both soils were irrigated for the first 2 years, and all other plots were dependent on natural rainfall. Shoot and root dry matter and N yield, and soil nitrate and ammonia N, were measured. In one set of green panic plots on each soil, canopy. litter, and surface soil temperatures were monitored continuously, and soil moisture at different depths was measured fortnightly. Shade stimulated shoot dry matter yield over the 3 years by up to 37% in green panic. 22% in rhodes, and 9% in speargrass. Shade decreased buffel yield on the clay soil but had no effect on the granitic soil. Relative increases in yield of shoot N were similar to those for shoot dry matter, except for buffel on the granitic soil where N yield was increased by 39% with no increase in shoot growth. Positive shade responses occurred in all 3 years but were reduced by extreme drought in year 3, particularly on the clay soil. Irrigation gave a greater shade response on the clay but not on the granitic soil. Root mass was lower under shade than in full sun. but there was no long-term trend of progressive decrease. and the change in N yield of roots did not appear to explain the gain in shoot N of the shaded pastures. Nitrogen percentage in the youngest expanded leaf was higher in the shade than the sun leaves only after about 2 to 2 5 months of shading. Surface soil nitrate and ammonia concentrations tended to be higher under shade for most harvests. Shade lowered temperature extremes of surface soil and litter by up to 10-12�C, and improved soil water status. compared with the sun plots. Soil water data were analysed to separate effects on plant water stress and soil microbial activity. The consistent positive response of shoot N yield to shade across grass species. weeds, and soil type. the delay in it becoming evident, and its longevity all support the hypothesis that shade enhances organic matter breakdown and N cycling. Harsh surface temperatures and low soil moisture in open sun pastures appear inimical to high microbial activity. Implications for pasture management are discussed. with the caveat that the outlined benefits of artificial shade may not necessarily arise with tree canopies.

Effects of nitrogen and lime on growth of Leucaena leucocephala cv. Cunningham on a red-yellow podzolic soil in south-eastern Queensland

1986 ◽  
Vol 26 (1) ◽  
pp. 23 ◽  
Author(s):  
S Sivasupiramaniam ◽  
R Akkasaeng ◽  
HM Shelton
Keyword(s):  
Podzolic Soil ◽  
Nitrogen Concentration ◽  
Dry Weight ◽  
Maximum Growth ◽  
Field Application ◽  
South Eastern ◽  
Shoot Dry Weight ◽  
Application Rates ◽  
Lime Application ◽  
Low Nitrogen

Field and glasshouse experiments were conducted on an acidic red-yellow podzolic soil of low nitrogen status from south-eastern Queensland to examine the use of nitrogen and lime in promoting leucaena growth. In the field, application of 25 kg nitrogen ha-l at planting increased shoot dry weight by 77, 88, 52 and 51% at weeks 5, 15, 32 and 52 respectively. Equivalent responses to lime (2.5 t ha-1) were 8, 3 1, 64 and 74% respectively. In the glasshouse, shoot, root and nodule dry weights were increased by nitrogen application rates of 50, 100 and 200 kg ha-1. Number, size and dry weight of nodules were suppressed at the highest rate (400 kg ha-1). Nitrogen concentration in youngest fully expanded leaves was increased to over 5% by nitrogen, and a critical nitrogen content of 4.5% (90% of maximum growth) is suggested. Inexplicably, lime application reduced shoot, root and nodule weights at high nitrogen applications. The apparent partial effectiveness of commercial leucaena Rhizobium and the implications of starter nitrogen and lime for leucaena establishment are discussed.

scholarly journals Differential side-effects of Bacillus thuringiensis bioinsecticide on non-target Drosophila flies

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Aurélie Babin ◽  
Marie-Paule Nawrot-Esposito ◽  
Armel Gallet ◽  
Jean-Luc Gatti ◽  
Marylène Poirié
Keyword(s):  
Side Effects ◽  
Bacillus Thuringiensis ◽  
Insect Pests ◽  
Larval Mortality ◽  
Specific Effect ◽  
Adult Emergence ◽  
Developmental Time ◽  
Field Application ◽  
Dependent Manner ◽  
Offspring Number

Abstract Bioinsecticides based on Bacillus thuringiensis (Bt) spores and toxins are increasingly popular alternative solutions to control insect pests, with potential impact of their accumulation in the environment on non-target organisms. Here, we tested the effects of chronic exposure to commercial Bt formulations (Bt var. kurstaki and israelensis) on eight non-target Drosophila species present in Bt-treated areas, including D. melanogaster (four strains). Doses up to those recommended for field application (~ 106 Colony Forming Unit (CFU)/g fly medium) did not impact fly development, while no fly emerged at ≥ 1000-fold this dose. Doses between 10- to 100-fold the recommended one increased developmental time and decreased adult emergence rates in a dose-dependent manner, with species-and strain-specific effect amplitudes. Focusing on D. melanogaster, development alterations were due to instar-dependent larval mortality, and the longevity and offspring number of adult flies exposed to bioinsecticide throughout their development were moderately influenced. Our data also suggest a synergy between the formulation compounds (spores, cleaved toxins, additives) might induce the bioinsecticide effects on larval development. Although recommended doses had no impact on non-target Drosophila species, misuse or local environmental accumulation of Bt bioinsecticides could have side-effects on fly populations with potential implications for their associated communities.

XRD-473 (AN EXPERIMENTAL BENZOYLPHENYLUREA): RATES AND OPTIMAL TIME OF APPLICATION TO WESTERN SPRUCE BUDWORM1,2

1986 ◽  
Vol 21 (1) ◽  
pp. 16-20
Author(s):  
Jacqueline L. Robertson ◽  
Haiganoush K. Preisler
Keyword(s):  
Spruce Budworm ◽  
Field Testing ◽  
Field Application ◽  
Optimal Time ◽  
Western Spruce Budworm ◽  
Time Of Application ◽  
Application Rates ◽  
Series Of Experiments

XRD-473 (N-(((3,5-Dichloro-4-(1,1,2,2-tetrafluoroethoxy) phenyl-amino) carbonyl)-2, 6-difluorobenzamide), a benzoylphenylurea (BPU), was tested in a series of experiments to estimate the optimal time and rate of application relative to instar distribution of a population of western spruce budworm Choristoneura occidentals Freeman. The optimal time of application was estimated to be the first 17 days after the first group of second instars emerges from diapause. Based on the rainfastness of the chemical, field application rates were estimated to be 3.5, 7.0, and 10.4 g/ha. XRD-473 appears to be more than twice as effective per unit rate than any BPU previously tested; if it becomes commercially available, XRD-473 would be a prime candidate for field testing.

Impact of deltamethrin insecticide on Chironomidae (Diptera) of prairie ponds

1990 ◽  
Vol 68 (2) ◽  
pp. 289-296 ◽  
Author(s):  
P. K. Morrill ◽  
B. R. Neal
Keyword(s):  
Natural Variation ◽  
Field Application ◽  
Basic Knowledge ◽  
Temporary Pond ◽  
Chironomid Larvae ◽  
Application Rates ◽  
Chironomid Community ◽  
Long Term Impact ◽  
Late Part

Deltamethrin insecticide was applied by air, at recommended field application rates (7.5 g/ha), to two prairie ponds in June, 1986. Larval and emerging Chironomidae densities were monitored in the treated ponds and in two untreated ponds for 1 month prior to spraying, the remainder of the summer after spraying, and in the late part of the following spring. Following deltamethrin application, the density of chironomid larvae declined by two orders of magnitude in the treated ponds relative to the untreated ponds, with all genera being affected. Chironomid emergence declined in both the treated and untreated ponds. The pattern of recovery of the chironomid community was followed by multivariate analysis of larval genera abundances and qualitative comparisons of emerging species. The two treated ponds recovered at different rates: the community in one pond appeared to have recovered by 2 months after treatment, whereas that of the other treated pond showed little recovery until 1 year following treatment. In view of the high natural variation of chironomid communities and their habitats on the prairies, basic knowledge about these temporary pond ecosystems must be gathered in order to understand the long-term impact on such habitats of using deltamethrin and other insecticides.

RESIDUAL TOXICITIES OF THREE INSECTICIDES TO FOUR SPECIES (COLEOPTERA: CARABIDAE) OF ARTHROPOD PREDATOR

1996 ◽  
Vol 128 (6) ◽  
pp. 1115-1124 ◽  
Author(s):  
Tamer Çilgi ◽  
Steve D. Wratten ◽  
Jacqueline L. Robertson ◽  
David E. Turner ◽  
John M. Holland ◽  
...  
Keyword(s):  
Laboratory Data ◽  
Field Application ◽  
Toxicity Data ◽  
Target Species ◽  
The United Kingdom ◽  
Application Rates ◽  
Bembidion Lampros ◽  
Nontarget Species ◽  
Arthropod Predator ◽  
Laboratory Bioassays

AbstractIn laboratory bioassays, four carabid species [Agonum dorsale (Pontoppidan), Bembidion lampros (Herbst), B. obtusum Serville, and Demetrias atricapillus (L.)] that are important predators of aphids in cereals in the United Kingdom were exposed to deposits of deltamethrin, dimethoate, or pirimicarb on glass for up to 72 h. We detected differences between compounds and species that are discussed in the context of exposure of these predators to insecticides in the field. We also describe problems involved in obtaining comparative toxicity data when dilutions of field application rates for target species are used in bioassays with nontarget species. Such problems add another dimension to risk assessment based on laboratory data.

Tillage-induced differences in the growth and distribution of wheat-roots

1992 ◽  
Vol 43 (1) ◽  
pp. 19 ◽  
Author(s):  
KY Chan ◽  
JA Mead
Keyword(s):  
Root Growth ◽  
Root Length ◽  
Root Distribution ◽  
Shoot Growth ◽  
Surface Soil ◽  
Root Length Density ◽  
Soil Layer ◽  
Soil Conditions ◽  
The Poor ◽  
Direct Drilling

Root growth and distribution of wheat under different tillage practices was studied in a 4-year-old tillage experimental site at Cowra, N.S.W. Tillage affected root density as well as distribution. Up to 98 days after sowing, root length density was lower (P < 0.05) in the 0.05-0.10 m layer of the direct-drilled soil than the conventionally cultivated soil. Poor root growth found in direct-drilled soils, which was significantly related to the poor shoot growth, was not caused by soil physical conditions, viz. higher bulk density and soil strength. Rather, biological factors were involved because fumigation completely eliminated the poor shoot growth and significantly increased root length density of the direct drilled soils. Compared to a compaction treatment, roots grown under direct drilling, in addition to having lower density, also had impaired function. Under conventional cultivation, significantly lower root length density was found in the surface soil layer (0-0.05 m) and maximum root length density was found in the 0-05-0.10 m layer. Fumigation did not change the root distribution pattern. This tillage-induced difference in root distribution reflected less favourable surface soil conditions as a result of cultivation, e.g. seedbed slumping, compared to the soil under direct drilling.

Genetic differences in the copper nutrition of cereals. I. Differential responses of genotypes to copper

1976 ◽  
Vol 27 (4) ◽  
pp. 453 ◽  
Author(s):  
EKS Nambiar
Keyword(s):  
Grain Yield ◽  
Shoot Growth ◽  
Copper Deficiency ◽  
Yield Potential ◽  
Wheat Cultivars ◽  
Lower Yield ◽  
Straw Yield ◽  
Stages Of Growth ◽  
Days To Heading ◽  
Apparent Association

Seven wheat genotypes, one or barley and one of oats were compared for their sensitivity to sub optimal supplies of copper, and their ability to recover from copper deficiency when copper was applied at defined stages of growth Copper deficiency delayed maturity, reduced the straw yield and severely depressed the gram yield In all genotypes. Genotypes differed considerably in their expression of deficiency symptoms, and In then- responses to the rate and time of copper application. For all genotypes, the supply of copper needed for maximum grain yield was significantly higher than that for maximum shoot growth. Halberd wheat and Clipper barley were less sensitive to copper deficiency than wheat cultivars Gabo, Glaive, Pinnacle, Chotilerma, UP-301, Duramba, and oats cultivar Avon. Genotypes with relatively higher yield potential were less sensitive to copper deficiency than those with lower yield potential, and the ability of hexaploid wheal to recover from deficiency increased with the increase in the number of days to heading of the normal plants There was no apparent association between dwarfness and sensitivity to copper deficiency in wheat.

scholarly journals Field Application of Dilophospora alopecuri to Manage Annual Ryegrass Toxicity Caused by Rathayibacter toxicus

Plant Disease ◽  
2006 ◽  
Vol 90 (2) ◽  
pp. 229-232 ◽  
Author(s):  
Martin J. Barbetti ◽  
Ian T. Riley
Keyword(s):  
Field Experiments ◽  
Negative Relationship ◽  
Field Application ◽  
Spore Suspension ◽  
First Year ◽  
Annual Ryegrass ◽  
Wheat Grain ◽  
Significant Treatment ◽  
Application Rates ◽  
Annual Ryegrass Toxicity

Field experiments were conducted in three consecutive years to determine the effect of Dilophospora alopecuri inoculation on the incidence of galls with Rathayibacter toxicus in annual ryegrass (Lolium rigidum). R. toxicus is carried into the grass by the seed gall nematode, Anguina funesta, and colonizes the ovules, displacing the nematodes, and producing the toxin responsible for annual ryegrass toxicity. Treatments included three types of D. alopecuri inoculum (naturally colonized ryegrass, cultures grown on sterilized wheat grain, and spore suspension) applied at different application rates and times. In the first year, naturally colonized ryegrass (30 kg ha-1), applied 1 week after the break of season, colonized wheat grain (150 kg ha-1) applied once at 1, 4, or 8 weeks or applied three times at 1, 4, and 8 weeks after the break of season, and spore suspension at heading, all significantly reduced the numbers of bacterially colonized galls (by 85 to 96%). In the second and third years, inoculum was applied at various rates and times. There were no significant treatment effects in the second year. In the third year, colonized wheat (450 kg ha-1) reduced the number of bacterially colonized galls by 73% and there was a significant negative relationship between inoculation rate of colonized wheat (5.5 to 450 kg ha-1) and the number of bacterially colonized galls (r = 0.86, P < 0.01). D. alopecuri has potential as a biopesticide for the management of annual ryegrass toxicity, but efficacy could be highly variable depending upon season or site, and uneconomic application rates might be needed.

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