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1.
Off-target glyphosate deposits were measured downwind of aerial silvicultural applications which used D8-46 hollow-cone hydraulic nozzles, ‘Micronair’ AU 5000 rotary atomisers, and the ‘Thru Valve Boom’ (030), with volume application rates of 35, 20 and 20 litre ha?1 respectively, and a glyphosate application rate of 2·1 kg ha?1. Crosswind spray lines were released 10 m above ground level over a short forest canopy, from a fixed-wing aircraft flying at 45 m s 1 in atmospheric boundary layers with average wind speeds and air temperatures of 2·2-3·7 m s?1 and 8-23°C at release height. Ground sheets and artificial foliage clusters were exposed at downwind distances of between 50 and 300 m. Glyphosate deposit measurements at various downwind distances (x) were fitted with non-linear regression lines; deposits were attenuated at rates inversely proportional to x at powers of 1·3-2·3. For a particular trial, deposits on ground sheets and artificial foliage were generally similar, and ranged between 19 and 0·04 mg m?2 over the sampling distances used. For 100-ha applications the estimated buffer-zone widths around water bodies were less than 50 m, whereas those around non-target vegetation ranged between 75 and 1200 m, depending on the application method and the meteorological conditions.  相似文献   

2.
The distribution and biological activity of spray deposits resulting from aerial applications of diluted and undiluted Bacillus thuringiensis, ‘Dipel 64AF’ against the gypsy moth, Lymantria dispar L., were examined in oak stands in south-eastern Ontario, Canada. The sprays were applied by fixed-wing aircraft equipped with four ‘Micronair AU4000’ atomizers. Application of diluted formulation at 30 BIU ha?1 in 6.0–6.4 litre generally resulted in a higher droplet density (10–28 cm ?2 leaf) than application of undiluted product at the same dosage rate in 1.8 litre ha?1 (4–10 cm ?2). However, spray deposits of undiluted product with a volume median diameter (Dv.5) of 90–130 μm caused as much mortality of gypsy moth larvae in bioassays of sprayed foliage as deposits of diluted product with a Dv.5 of 150–350 μm despite a two- to three-fold reduction in droplet density. Our data suggest that by using fine spray atomization, undiluted application of these formulations can offer the same efficacy against gypsy moth as coarsely atomized sprays of diluted product.  相似文献   

3.
A rapid, sensitive and specific high-pressure liquid chromatographic method was developed to analyse residues of binapacryl, bupirimate and diflubenzuron on mature foliage and fruit at intervals after application of the compounds to Worcester and Cox apple trees. The three compounds were applied as commercial formulations in trials to compare integrated pest management with routine farm spray-programmes. The identities of the residues were confirmed by a combination of thin-layer chromatography, ultraviolet spectrometry and gas chromatography/mass spectrometry. Only diflubenzuron persisted on foliage until leaf-fall. None of the applied compounds was detectable on harvested fruit, the minimum quantifiable residue levels being 1, 5 and 2.5 μg kg?1 fresh weight for binapacryl, bupirimate and diflubenzuron, respectively.  相似文献   

4.
Total deposits and their distribution on bush and dwarf hedgerow apple trees, sprayed at the late dormant and full foliage stages with a copper fungicide by five different methods, were estimated by colorimetric determination of the acid-extracted copper from all the tree parts, and for comparison purposes were converted to equivalent volumes retained. The bush trees were sprayed by hand lance (4500 litresha-1), by automatic nozzle mast sprayer (2250 litres ha?1), by conventional air-blast sprayer at medium volume (1125 litres ha?1) and low volume (560 litres ha?1), and by hand-directed ultra-low-volume (ULVH) fan-assisted spinning-disc sprayer (6 litres ha?1). The hedgerow trees were sprayed by conventional air-blast sprayer at low volume (560 litres ha?1) and by an experimental tractor-mounted ultra-low-volume air-blast sprayer (45 litres ha?1). At the late dormant stage, the bush trees retained only 9–22 % of the total spray applied by all methods, except that those sprayed by the hand-directed ULVH sprayer retained 57%. At the full foliage stage, when most of the spray was deposited on the leaves, retention for all methods of application was 22–37%. The hedgerow trees at late dormancy retained 6% of the spray applied in low volume and 10% of that by tractor-mounted ultra-low-volume methods, but at full foliage, retention was 25 and 63 %, respectively. On both types of tree the proportions of the spray deposited on the tree components were related to the surface areas of those components.  相似文献   

5.
Diflubenzuron, 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea was used to control the pine looper population in about 1160 ha of Scots pine stand in eastern Finland in summer 1984. The control measure was effective, resulting in the collapse of the population in the treated area. Residues of diflubenzuron and two of its metabolites, 4-chloroaniline and 4-chlorophenylurea, were determined in water, pine needles, litter, humus, boleti and other wild mushrooms, bilberry (Vaccinium myrtillus L.) and cowberry (Vaccinium vitis-idaea L.) samples taken from this area. In water samples taken from the treated area diflubenzuron was still detected at concentrations of 0.1 μg litre?1 2 months after application. No diflubenzuron was detected in this area the following year, nor outside the treated area. Neither metabolite was detected at any time. The sum of diflubenzuron and its metabolites in the litter layer was, on average, 0.7mg kg?1 both 1 week and 1 month after the application. The next year, however, it had increased to 1.4 mg kg?1. Diflubenzuron and its metabolites were not detected in the humus layer. The amount of diflubenzuron residues in the pine needles was, on average, 3.0 mg kg ?1 1 day after the application, but in 2 months the level had decreased to 0.2-0.3 mg kg ?1 or was not detectable. The following year the sum of diflubenzuron and its metabolites in two pine-needle samples was 0.3 and 1.6 mg kg ?1. The sum of diflubenzuron and its metabolites in wild mushrooms was, on average, 0.07 mg kg ?1 1 week after the application, but the following year no residues were detected. No residues were found in the boletus samples. The residues of diflubenzuron and its two metabolites in bilberries totalled, on average, 0.2 mg kg ?1 1 day after the application, and 6 μg kg ?1 the following year. The sum of diflubenzuron and metabolites in cowberries was, on average, 0.2 mg kg ?1 1 month after application.  相似文献   

6.
Aerial spray applications of the herbicide glyphosate were made over a forest canopy under various meteorological conditions. A ‘Thru Valve Boom’ dispersal system carried by a Cessna 188 fixed-wing aircraft flying at 49 m s?1 was used to generate an aqueous spray cloud with a volume median diameter of 150 μm. Glyphosate deposits from multiple overlaid crosswind line sources released at 10 m above ground level were measured on ground sheets and artificial foliage at downwind distances between 50 and 400 m. Trials were conducted in stable, neutral and unstable atmospheric boundary layers with average wind speeds between 2·2 and 5·7 m s?1 and vertical intensities of turbulence between 0·07 and 0·16. Linear regression lines fitted to logarithmically transformed measurements and downwind distances (x) gave statistically significant correlation coefficients (P = 0·01), and were compared by ANOVA. Glyphosate deposits on ground sheets and artificial foliage were attenuated at rates inversely proportional to x to the power 1·7-4·3. Regression line comparison showed that, in general, deposits on ground sheets decreased with increasing wind speed and intensity of turbulence, and some statistically significant differences were found in slopes and elevations of regression lines from different trials. However, deposits at the 50-m station increased with wind speed due to the large-drop cloud component. Regression line comparison for deposits on artificial foliage showed that, in general, they were highest in the intermediate wind speed-neutral stability case and similar in the high wind speed-unstable and low wind speed-stable boundary layers, although deposits at the 50-m station also increased with wind speed.  相似文献   

7.
In an extension of previous work, deposits and residues of binapacryl, bupirimate and diflubenzuron on mature foliage and the peel of developing fruit of Worcester and Cox apple trees were monitored throughout the 1980 season following applications by mistblower sprayer. The three compounds were applied as commercial formulations in trials to compare integrated pest management with routine farm spray programmes. In contrast to previous results, all three compounds persisted on foliage until leaf-fall and were detected on the peel of harvested fruit. The mean residue of diflubenzuron on harvested Worcester fruit was 0.05 mg kg?1 fresh weight and on harvested Cox fruit was 0.02 mg kg?1 fresh weight. Binapacryl and bupirimate were present on harvested fruit of both cultivars. The unexpectedly long persistence of these chemicals in 1980 remains unexplained, but may be due to climatic factors.  相似文献   

8.
Five commercial formulations of azadirachtin-A (AZ-A) Margosan-O®, Azatin-EC®, Neem-EC®, RH-9999 and Neemix® 4.5, were investigated for their volatilization and washoff potential in laboratory studies. Prior to the investigation, RH-9999 (a wettable powder) was mixed with water to provide an end-use formulation containing 35·6 g AZ-A kg-1, while the remaining four formulations were investigated without dilution. Volatilization and washoff of AZ-A occurred more from white spruce foliage than from wax-coated glass plates. Neem-EC provided the lowest amount of loss, whereas Margosan-O provided the highest. Physical properties and atomization behaviour of the five formulations indicated that Azatin-EC was highly viscous and caused phase separation in droplets collected on glass plates after atomization in a rotary atomizer. RH-9999, despite its low viscosity, caused phase separation in droplets because of the heterogeneity of the wettable powder formulation. Based on the minimum loss of AZ-A due to volatilization and washoff from spruce foliage, and on the minimum potential for phase separation in droplets after atomization in a rotary atomizer, Neem-EC was considered to be the most appropriate choice for use in field studies to investigate environmental persistence and fate of AZ-A in terrestrial and aquatic matrices of a forest ecosystem. The Neem-EC formulation was sprayed at 40 and 80 g AI ha-1 over single spruce trees and on litter and soil plots selected in a mixed-wood boreal forest in Ontario, Canada. In addition, outdoor aquaria containing stream water and sediment were also fortified with the formulation at 400 and 800 g AI ha-1. Persistence of AZ-A was evaluated using one-year-old spruce needles, current-year shoots, spruce bark, litter, soil, stream water and sediment. The duration of persistence varied from 3 to 6 days in terrestrial matrices, whereas it ranged from 8 to 13 days in water, and 2 to 3 days in sediment. The half-life (DT50) values ranged from 10·7 h (for soil) to 71·6 h (for spruce bark) at the lower dosage rate, and from 18·8 h (for litter) to 76·2 h (for bark) at the higher dosage rate. The DT50 value for stream water was about 35 h regardless of the dosage rate applied. The data indicated that AZ-A was appreciably labile and short-lived in different forestry matrices, with low DT50 values. © 1997 SCI  相似文献   

9.
In glasshouse experiments, additions of 10–100 g 1?1 ammonium sulphate enhanced the phytotoxicity to broadleaved weeds and cereals of several water-soluble herbicides applied post-emergence in 75–300 1 ha?1 with hydraulic nozzles. Studies with dichlorprop potassium salt and chickweed Stellaria media (L.) Vill. examined interactions between ammonium sulphate and environmental, application and formulation factors. Simulated rainfall immediately after spraying greatly reduced dichlorprop activity, whether or not ammonium sulphate was present. However, when there was an interval of 2–24 h between spraying and rainfall, the additive increased phytotoxicity. Surfactants tended to reduce dichlorprop phytotoxicity to Stellaria media, both in the presence and absence of ammonium sulphate. Certain other inorganic salts including sodium sulphate also enhanced phytotoxicity. Applications by rotary atomizer in very low spray volume (15 1 ha?1, 250–280 μm drops) were less effective than conventional 150 1 ha?1 applications. When very low volume application was used, addition of ammonium sulphate or nitrate tended to reduce activity further. In the field, ammonium sulphate significantly increased the effects against weeds of a commercial dichlorprop potassium salt formulation applied conventionally in 200 1 ha?1 spray volume. Neutralized phosphoric acid had a similar effect but a mixture of this additive and ammonium sulphate reduced phytotoxicity. Both additives slightly increased dichlorprop injury to barley.  相似文献   

10.
The effects of two herbicides, glyphosate (as a 359 g litre?1 SL) and hexazinone (as a 50gkg?1 granule) on soil microbial population, carbon dioxide evolution, and in-vitro growth of five species of ectomycorrhizal fungi were investigated. Glyphosate at 0–54 and 3.23 kg a.i. ha?1 and hexazinone at 1. 2 and 8 kg a.i. ha?1 did not reduce soil microbial population or carbon dioxide evolution in the long term (6 months). However, there was a significant short-term (2 months) effect of glyphosate on both fungal and bacterial counts at the 0.54 kg ha?1 treatment. In in-vitro tests, Cenococcum graniforme. Hebeloma crustuliniforme and Laccaria laccata were more susceptible to both herbicides than was Suillus tomentosus. which was, in turn, more susceptible than Paxillus involutus. The growth of all five ectomycorrhizal fungi was significantly reduced when subjected to concentrations above 50 μl formulation litre?1 (glyphosate) or 50 μg formulation litre?1 (hexazinone).  相似文献   

11.
A non-volatile oil-based spray mix of a low-vapour-pressure insecticide, aminocarb, containing an oil-soluble red dye was applied at a dosage rate of 70 g AI in 1-5 litre ha?1, using a fixed wing aircraft equipped with four ?Micronair’?® AU3000 atomizers, over a 1000 × 500 m spray block selected in Bathurst, New Brunswick, Canada. Spray was applied twice, at an interval of five days, to provide a total dosage rate of 140 g AI in 3.0 litre ha?1. Spray mass recovery was assessed on glass plates and droplets were collected on ?Kromekote’?® cards, both at ground level. The stain sizes were grouped into different categories. The area containing the stains was excised, and the aminocarb present was quantified by gas-liquid chromatography (GLC). The mass of aminocarb per droplet in each stain size category was evaluated. From the mass, the spherical droplet diameter (d), number and volume median diameters (DN.5 and Dv.5 respectively), a new parameter [mass (of aminocarb) median diameter] (DM.5), and the droplet size spectra were calculated. The DM.5 for the first application was 56 μm, which was identical to the Dv.5. whereas the DN.5 was smaller at 45 μm. The corresponding values for the second application were: DM.5 = Dv.5 = 63 μm, but the DN.5 was 53 μm. Because the spray mix was non-volatile, all the droplet size spectra parameters were identical both at spray release height and at ground level. The present study has provided, for the first time in the literature, a novel method to determine directly the spherical diameters of the droplets deposited on artificial samplers, without having to go through the tedious procedures of spread factor measurements under laboratory conditions. In fact, the present study has made it possible to calculate spread factors under field conditions, by using the stain diameters measured and the spherical diameters calculated from the aminocarb concentration levels.  相似文献   

12.
The mobility and decomposition of the herbicide fluroxypyr (4-amino-3,5-dichloro-6-fluoro-2-pyridyloxyacetic acid) was studied under field conditions in a sandy soil and a clay soil. Leachate was collected in lysimeters with undisturbed soil (sand) and in tile-drained plots (clay). Soil samples to a depth of one metre were also collected in both soils to characterize the temporal depth distribution of fluroxypyr in the profiles. The herbicide was applied as the I-methylheptyl ester of fluroxypyr at two rates, 187.5 and 375.0 g a.e. ha?1, representing the normal and double the dose of the compound used for spring cereals. Some lysimeters received supplementary watering. Only two leachate samples (one from each soil) had concentrations of fluroxypyr above the detection limit (1 μg litre?1), i.e. 2 and 5 μg litre?1. Both samples were collected within two months after application, when less than 2 mm of drainage had been collected. The methylheptyl ester of fluroxypyr was not found in any of the samples. Fluroxypyr levels above the detection limit in soil (5 μg kg?1 dry soil), were never found below the topsoil (0.2 m) in the clay profile, while, in the sandy profile, levels just above the detection limit were found occasionally in deeper soil layers. Concentrations were reduced to undetectable or very low levels within three months after spraying.  相似文献   

13.
Petroleum spray oil (2, 4 and 6% in water) was applied to Valencia orange, Citrus sinensis (L.) Osbeck, for the control of Chinese wax scale, Ceroplastes sinensis del Guercio, using a low-volume ( <2000 litre ha?1)air-blast (LV AB) sprayer, a low- to high-volume (L-HV) (up to 7000 litre ha?1) sprayer with four fan-assisted rotary atomiser (FARA) spray heads mounted on a vertical tower, and a high-volume (>7000 litre ha?1) oscillating boom (HV OB) sprayer. The most effective sprayer was the L-HV FARA sprayer. The most cost-effective treatment was a 20 ml litre?1 (60 litre oil ha?1) spray applied at 3000 litre ha?1 by the L-HV FARA sprayer. It gave mortality equivalent to a standard 20 ml litre?1, 10 700 litre ha?1 spray (214 litre oil ha?1) applied by the HV OB sprayer but with 72% less spray and significantly less oil deposited per cm2 of leaf area. Equivalent or significantly (P = 0·05) higher mortality than that given by the 10 700 litre ha?1 HV OB spray was given by the 40 ml litre?1, 3000 (120 litre oil ha?1) and 60 ml litre?1, 2180 and 3000 litre ha?1 (130·8 and 180 litre oil ha?1) L-HV FARA sprays, but the 60 ml litre?1 sprays deposited more oil per cm2 than the 20 ml litre?1 HV OB spray and were considered to be potentially phytotoxic. The least effective sprayer was the LV AB sprayer, which applied a 60 ml litre?1 spray (57·6 litre oil ha?1) at 960 litre ha?1. Linear relationships were established for Chinese wax scale mortality, transformed using an angular transformation (arcsin proportion), versus log10 spray volume for the 20, 40 and 60 ml litre?1 sprays applied by L-HV FARA at 1260,2180 and 3000 litre ha?1, mortality versus log10 μg oil cm?2 and log10 μg oil versus log10 volume of oil sprayed.  相似文献   

14.
A field trial was conducted in 1994 to determine the foliar deposit of tebufenozide (RH5992), applied aerially, and its efficacy against spruce budworm, Choristoneura fumiferana (Clem.). A commercial 240 g litre-1 formulation of the insecticide (Mimic 240LV) was mixed with water, dyed with a tracer dye (Rhodamine WT) and sprayed with a light fixed-wing aircraft. Six application strategies were tested. Five used 70 g AI ha-1 in a spray volume of 1 or 2 litre-1 ha-1 with single or double applications; the sixth was an unsprayed control. Results show that the spectra of the spray applications were, with one exception, fairly uniform. Volume and number median diameters ranged from 100 to 130 μm and 27 to 72 μm, respectively. Mean number of drops cm-2 on Kromekote cards were <2·0 for strategies where either 1 or 2 litre ha-1 were sprayed. Nevertheless no one strategy produced droplet densities that were significantly different (P<0·05) from the other strategies. Tebufenozide recovered from foliage averaged 2·5 to 5·9 μg g foliage-1 when 1 litre ha-1 was sprayed and 5·8 to 6·8 μg g foliage-1 after 2 litre ha-1 were sprayed. When a single application was the strategy used, the mean number of droplets cm-2 and μg tebufenozide g foliage-1 ranged from 1·2 to 1·4 and 2·5 to 5·9, respectively. With double applications, the same response parameters ranged from 0·3 to 1·9 and 2·5 to 6·8, respectively. Budworm population reductions (%) and the number of larvae that survived tebufenozide treatments were significantly different (P<0·05) from the controls. After strategies that used 1 litre spray ha-1, mean percentage population reductions ranged from 61·4 to 93·6 whereas populations were reduced by 85·6 to 98·3% when 2 litre ha-1 were sprayed. After double applications the mean percentage population reductions ranged from 93·6 to 98·3, but single application strategies resulted in mean reductions of 61 to 86%. Mean population reductions in the controls were 61%. The mean number of larvae per branch that survived spray strategies of 1 litre ha-1 ranged from 1·3 to 7·4, and from 0·4 to 1·3 when 2 litre ha-1 was the spray volume. In the controls an average of 10·2 larvae survived. With one exception, mean percentage defoliation in the treated areas was also significantly less (P<0·05) than that in the control. Mean defoliation in trees sprayed at 1 litre spray ha-1 ranged from 40 to 62·8% whereas those treated at 2 litre ha-1 had mean defoliation levels from 31·5 to 62·8%. In contrast, average defoliation in the controls was 92·1%. When a single application was the spray strategy, mean defoliation ranged from 31·5 to 62·8%. These data imply that a double application of tebufenozide at 70 g in 2 litre ha-1 was the most efficacious strategy. However, analyses of the data also show that the primary influence on deposits and defoliation was interactions between number of applications and spray. Nevertheless the two independent variables acted without significant interactions when influencing percentage reductions of spruce budworm populations. © 1998 SCI  相似文献   

15.
Spray deposit patterns on simulated and live foliage of balsam fir and white birch were determined at different heights and at periphery and interior locations of the tree crown, following aerial and ground applications of fenitrothion formulations over a boreal forest near Searchmont, Ontario. Droplet size spectra and AI deposits were assessed at ground level with ‘Kromekote’ card/glass plate units. Aerial application was made with a Cessna 188 aircraft fitted with ‘Micronair’ AU3000 atomizers. For ground application, a ‘Soloport’ 423 backpack mistblower fitted with an extension tube and a diffuser nozzle at the tip was used. Deposit data on the ground samplers indicated significantly larger droplets and greater deposits from the aerial spray trial than from the mistblower treatment. However, foliar deposits at tree canopy level were only slightly higher in the former trial than in the latter. Analysis of spray deposits on simulated and live fir foliage showed definite gradients in deposit levels, decreasing from top to bottom crown, and from periphery to inner tree crown. In the birch tree crown, such gradients were not observed. The simulated leaves generally acted as better collectors of spray droplets than the natural leaves. The overall mean deposit values, expressed in ng cm?2, showed a wide variation, although there was generally a close relationship between the deposits on the simulated and natural surfaces.  相似文献   

16.
Diflubenzuron, topically applied (0·5 μg insect?-1) to Cydia pomonella (L.) at pupal ecdysis disturbed growth and development of oocytes. It delayed the adult ecdysis and caused a decrease in both thickness of the follicular epithelium and the size of the basal oocyte during the pupal development. On the other hand, the size of basal oocytes, the protein content per ovary and the number of oocytes per ovary recorded in newly emerged adults were significantly reduced after diflubenzuron treatment. These results, together with observations in several other species, indicate that the reduction in fecundity and egg viability is probably due to interference of diflubenzuron with the vitellogenesis process.  相似文献   

17.
Residues of the herbicide dinoseb were determined gas chromatographically in lentils which had been treated at two locations in Saskatchewan with post-emergence applications of dinoseb at 1.4 and 1.7 kg ha?1. Herbicide residues, determined at selected times after application, were not detected at the limit of detection of the analytical method (0.05 mg kg?1) in either the seed and straw at maturity, or in the green foliage six to eight weeks after application. Recoveries of dinoseb were 76% from fortified green foliage at the 0.1 mg kg?1 level, and 64% from fortified seed at the 0.05 mg kg?1 level.  相似文献   

18.
BACKGROUND: A mixture of trifloxystrobin and tebuconazole is excellent in controlling both powdery and downy mildew of grapes. The objective of the present work was to study the behaviour of trifloxystrobin and tebuconazole on grape berries and soil following treatment with Nativo 75 WG, a formulation containing both fungicides (trifloxystrobin 250 + tebuconazole 500 g kg?1). This study was carried out for planned registration of this mixture for use on grapes in India. RESULTS: Initial residue deposits of trifloxystrobin and tebuconazole on grapes were below their maximum residue limit (MRL) of 0.5 and 2 mg kg?1, respectively, when Nativo 75 WG was applied at the recommended dose of 175 g product ha?1. The residues dissipated gradually to 0.02 and 0.05 mg kg?1 by 30 days, and were below the quantifiable limit of 0.01 mg kg?1 at the time of harvest (60 days after the last treatment). Trifloxystrobin and tebuconazole dissipated at a pre‐harvest interval (PHI) of 36 and 34 days, respectively, from the recommended treatment dose. The acid metabolite of trifloxystrobin, CGA 321 113, was not detected in grape berries at any point in time. Soil at harvest was free of any pesticide residues. CONCLUSION: Residue levels of both trifloxystrobin and tebuconazole were below MRLs when grapes were harvested 30 days after the last of four applications of 175 g product ha?1 (trifloxystrobin 44 g AI ha?1, tebuconazole 88 g AI ha?1) under the semi‐arid tropical climatic conditions of India. Copyright © 2010 Society of Chemical Industry  相似文献   

19.
The effect of fungicide spray droplet density (droplet cm-2), droplet size, and proximity of the spray droplet deposit to fungal spores was investigated with Mycosphaerella fijiensis ascospores on the banana (Musa AAA) leaf surface for two contact fungicides: chlorothalonil and mancozeb. When droplet size was maintained at a volume median diameter (VMD) of 250 μm while total spray volume per hectare changed, M. fijiensis ascospore germination on the leaf surface fell below 1% for both fungicides at a droplet deposit density of 30 droplet cm-2. At a droplet deposit density of 50 droplet cm-2, no ascospores germinated in either fungicide treatment. When both droplet size and droplet cm-2 varied while spray volume was fixed at 20 litre ha-1, ascospore germination reached 0% at 10 droplet cm-2 (VMD=602 μm) for both fungicides. At lower droplet densities (2–5 droplet cm-2 VMD=989 μm and 804 μm respectively), ascospore germination on the mancozeb-treated leaves was significantly lower than on the chlorothalonil-treated leaves. The zone of inhibition surrounding a fungicide droplet deposit (VMD=250 μm) on the leaf surface was estimated to extend 1·02 mm beyond the visible edge of the spray droplet deposit for chlorothalonil and 1·29 mm for mancozeb. The efficacy of fungicide spray droplet deposit densities which are lower than currently recommended for low-volume, aerial applications of protectant fungicides was confirmed in an analysis of leaf samples recovered after commercial applications in a banana plantation. Calibrating agricultural spray aircraft to deliver fungicide spray droplets with a mean droplet deposit density of 30 droplet cm-2 and a VMD between 300 and 400 μm will probably reduce spray drift, increase deposition efficiency on crop foliage, and enhance disease control compared to aircraft calibrated to spray finer droplets. © 1997 SCI.  相似文献   

20.
C. KJÆR 《Weed Research》1994,34(6):453-459
Effects of the herbicide chlorsulfuron on growth and reproduction of black bindweed (Polygonum convolvulus L.) plants were investigated in a controlled environment chamber and a greenhouse over a full life cycle. Biomass of P. convolvulus was stimulated at 0.4 g a.i. ha?1, but at higher doses it was reduced compared with controls. Leaf production of plants treated with 1.6 g a.i. ha?1 was initially totally inhibited, but these plants resumed leaf production 10 days after treatment. Chlorsulfuron treatment resulted in higher proportions of small and large leaves compared with controls. Because the life-span of the plants increased with increasing doses of chlorsulfuron, seed production was not affected at doses up to 1.6 g ha?1, even though significant effects were found on both biomass and leaf production. At rates of 1.6–4 g a.i. ha?1 seed production decreased. Plant mortality was low in this study, reaching 33% at the highest rate of chlorsulfuron. Effets sublétaux du chlorsulfuron sur la renouée faux-liseron (Polygonum convolvulus L.) Les effets du chlorsulfuron sur la croissance et la reproduction de la renouée faux-liseron (Polygonum convolvulus L.) ont étéétudiés en serre et en conditions controlées sur un cycle complet. La biomasse de P. convolvulusétait stimulée à 0,4 g m.a. ha?1 mais à doses plus élevées elle était réduite par rapport à celle des témoins. La production de feuilles de plantes traitées à 1,6 g m.a. ha?1était initialement totalement inhibée mais ces plantes reprenaient leur production de feuilles 10 jours après le traitement. Les plantes traitées au chlorsulfuron avaient une plus grande proportion de feuilles petites et grandes que les témoins. Comme la durée de vie des plantes s'accroissait avec la dose de chlorsulfuron, la production de graines n'était pas affectée jusqu'à la dose 1,6 g m.a. ha?1, meme si des effets significatifs étaient détectés sur la biomasse et la production de feuilles. À des doses comprises entre 1,6 et 4 g m.a. ha?1, la production de graines diminuait. La mortalité des plantes était faible dans cette étude, atteignant 33%à la plus haute dose de chlorsulfuron. Subletale Wirkungen von Chlorsulfuron auf den Gemeinen Windenknoterich (Polygonum convolvulus L.) In Ecophyt- und Gewachshausversuchen zur Wirkung von Chlorsulfuron auf Wachstum und Reproduktion des Gemeinen Windenknoterichs (Polygonum convolvulus L.) war die Biomassebildung bei 0,4 g AS ha?1 verstarkt, bei hoheren Dosen jedoch verringert. Bei 1,6 g AS ha?1 war die Blattentwicklung zunachast fur 10 Tage nach der Behandlung ganzlich unterdruckt. Der Anteil kleinerer und großerer Blatter war hoher. Mit zunehmendem Aufwand des Herbizids verlangerte sich der Entwicklungszyklus, so daß bis zu 1,6 g AS ha?1 die Samenproduktion nicht zuruckging, trotz signifikanter Wirkung sowohl auf die Biomasse als auch auf die Blattbildung. Bei Dosen Uber 1,6 bis 4,0 g AS ha?1 wurden weniger Samen gebildet. Die Absterberate war bei diesen Versuchen niedrig und betrug bei der hochsten Chlorsulfuron-Dosis 33%.  相似文献   

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