摘要:

SummaryIn 49 olive tree groves in southern Spain under non‐tillage and treated in the autumn with simazine, a total of 315 weed species was identified. However, only eight annual specics reached a moderate mean infestation of infested ficlds. In each field the number of observed species ranged from 4 to 78. The most important annual species that survived simazine treatment wereLolium rigidum, Galium tricornutumandSherardia arvensisand, locally in a few fields, others such asAmaranthusspp.,Conyzaspp.,Pulicaria paludosa, Sinapis alba. Torilis arvensisandRumex bucephalophorus. Sedum album, R. bucephalophorus, P. paludosa, Briza maximaandHypericum perforatumwere mainly found in slope soils with high altitude and low carbon content.Cyperus rotundus, Conyza banariensi, Amaranthus blitoides, Galium spuriumandDiplotaxis virgatawere found at high densities in irrigated fields. Simazine residues recorded 6 months after herbicide application were very low, amounting on average to levels less than 3% of the applied rate. In soil treated with simazine for 7 years. simazine degradation was much faster than in previously untreated soil, particularly at temperatures of 15‐2

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1996.tb01795.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryIn an investigation of the possible reasons for tolerance lo fluroxypyr byGalium aparineL. (cleavers), a wide range of variation in total herbicide retention was exhibited by nine diverse populations from throughout Europe. Although these differences in fluroxypyr relention became negligible when considered on a unit area basis, a two‐fold difference was maintained per unit dry matter. There was no difference in fluroxypyr uptake between a fluroxypyr‐tolerant and a fluroxypyr‐susceptible population, and differences in translocation between the two populations did not seem to explain the differential tolerance. It is suggested that differential metabolic detoxification may be the main reason for the variation in response to fluroxypyr by populations ofG. ap

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1996.tb01796.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryResistance of weeds to triazine herbicides has been recorded in many countries. The extent of the problem in South Africa is uncertain. In a pilot study, the atrazine resistance ofAmaranthus hybridusL. (smooth pigweed) was investigated. Suspected resistant (R) and susceptible (S) biotypes were treated with commercially formulated atrazine. After post‐and pre‐emergence applications under tunnel conditions, it was found that the suspected R biotype plants were not affected at herbicide dosages of belween 1.25 and 25.0 kg a.i. ha‐1, i.e. up to 20 times gieater than the lowest recommended dosage. However, the S biotype plants were killed by the lowest dosage. In the fieid, mortalities in the R biolype were not observed after post‐emergence applications of 1.25‐10.00 kg a.i. ha‐1. In contrast, all S biotype plants were killed. In tunnel experiments, the R biotype was also found to be resistant to cyanazine and cyanazine+atrazine, while slight tolerance to linuron was observed. All these treatments resulted in 100% mortality of the S biotype. Although S biotype seeds oiA. hybriduswere found to germinate slightly sooner under controlled conditions than R biotype seeds, preliminary results suggest that there are no major differences. Indications are that, although the growth of the S biotype may be greater than that of the R biotype, the competitive effect of the two biotypes on crop seedlings may well

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1996.tb01797.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryThe movement and persistence of imazaquin, oxyfluorfen, flurochloridone and terbacil residues were studied using a bioassay based on the shoot growth ofRaphanus sativusL. var,radiculaDC (radish) in a sandy loam soil under field conditions in 1992 and 1993. Imazaquin (0.3 kg a.i. ha‐1) was more mobile in the soil than the other three compounds. In 1992, under heavy rainfall conditions, the herbicide was distributed down to 60 cm in amounts of about 0.01 mg kg‐1. Conversely, in the dry year of 1993, the maximum depth of penetration was 20 cm and persistence in the surface soil layer (0‐5 cm) was greater. After the first month in 1992, residues of terbacil were distributed in the 0‐20 cm layer, and after 2, 3 and 5 months the herbicide had penetrated to a depth of 40 cm. In 1993, terbacil residues were distributed in the 0‐10 cm layer only. In both years, residues of flurochloridone (1.0 kg a.i. ha‐1) were located mainly in the 0‐5 cm layer, but there was some penetration to 10 cm. Oxy‐fluorfen (1.2 kg a.i, ha‐1) showed least mobility in the soil profile. It was retained in the 0‐5 cm layer throughout the experimental pe

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1996.tb01798.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryThe persistence and movement of residues of alachlor, alrazine and metribuzin were measured in a mini‐lysimeter system in the field. This comprised a number of soil columns (11 cm diametert; 30 cm long), and permitted the vertical distribution of residues to be determined at. intervals alter application and the collection and analysis of leaehale water. Laboratory experiments were also performed to determine the degradation rates of the three herbicides and their strengths of adsorption by the test soil. The results showed an order of degradation rate of metribuzin>alachlor>atrazine and an order of adsorption of alacblor>atrazine>melribuzin. Movement of residues in the soil columns and concentrations in the leachate were inversely related to the strength of adsorption. Parameters derived from the laboratory data were used in conjunction with weather data for the period of the field experiment in three mathematical models of pesticide leaching: VARLEACH, LEACHP and PRZM2. In most instances, the models gave acceptable predictions of the distribution of residues in soil. This was particularly so for the less mobile compound alachlor. With the most mobile compound, metribuzin, residues were not well predicted at the later sampling dates. All three models gave accurate predictions of the volumes of drainage water, but none of them predicted the concentrations of herbicide in the leachate, presumably because they do not take account of preferential flow pathways of water and solute in the soi

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1996.tb01799.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryBensulfuron inhibited root growth of waterseeded rice (Oryza sativaL.) plants in a solution culture system. Rice root growth was more sensitive to bensulfuron than was shoot growth. A1 2.5 × 10‐9M bensulfuron, plant height, number of leaves and number of roots were not significantly affected, while root growth was reduced, Seedlings treated 3 or 4 days after emergence showed a significant reduction of total root length by the second day after treatmeni. Root growth inhibition was proportional to duration of treatment; however, treatment for 2 days was necessary to affect root growth, Bensulfuron decreased the mitotic index and the mitotic height in root tips. At 5 days after treatment, only 0.7% of the cells were dividing and mitotic height was 68% of cont

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1996.tb01800.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummarySize, germination and viability of seeds as well as growth of seedlings derived from three weed species were studied in a pot trial.Fallopin convolvulus(L.) A. Loeve,Galium. spuriumL. andThlaspi arvenseL. were treated with MCPA or tribenuron‐methyl at four doses and at five growth stages, from seedling stage to flowering, InG. spuriumsubnormal doses of tribenuron‐methyl, applied at intermediate growth stages, greatly reduced seed weight, gennination, viability, seedling shoot biomass and root biomass. Germination and viability, as well as the shoot biomass and root biomass of seedlings, were highly correlated with seed weight. In addition, but to a smaller extent, seed weight was reduced inF. convolvidusandT. arvenseby tribenuron‐methyl and inG. spuriumby MCPA. Germination was reduced inF. convolvulusby MCPA and inT. arvenseby tribenuron‐methyl. However, the effects varied greatly depending on the growth stage at appl

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1996.tb01801.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryThe influence of water stress on the absorption and translocation of14C‐labelled fenoxapropethyl and imazamthabenz‐methyl inAvena fatuaL. (wild oat) was studied. The phytoioxicity toA. fatuaof both herbicides with a droplet application was also examined under water stress conditions. The absorption of both fenoxaproethyl and imazamethabenz‐methyl was reduced by waler stress when the plants were harvested within 24 h after herbicide application. Up to 48 h after the application, the translocation out of the treated lamina of both herbicides, based on percentage of applied14C. was reduced under water stress conditions. When havested 96 h after herbicide application, however, water stress no longer significantly affeaed the absorption and translocation of either herbicide. When the herbicides were applied as individual droplets, water stress reduced the phytotoxicity of fenoxaprop‐ethyl but not that of imazamethabenz‐methyl. It is concluded that the changes in herbieide absorption and translocation may not be the major physiological processes associated with differential whole‐plant response oiA faiuato fenoxaprop‐ethyl and imazamefhabenz‐methyl und

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1996.tb01802.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryGreenhouse and field trials were carried out from 1990 to 1993 on a silty‐clay soil in central Italy to assess the risk of carry‐over of imazethapyr and rimsulfuron residues. Turnip and sunflower were the most sensitive species to rimsulfuron residues (damaging thresholds lower than l ng a.i. g‐1), whereas sugar beel. turnip, oilseed rape and grain sorghum proved to be the most sensitive species to imazethapyr (damaging thresholds ranging from 0.5 to 6 n g a.i. g‐1). The time required for 50% imazethapyr disappearance (DT50) from the upper soil layer (0‐0.1 m)ranged from 18 to 21 days, whereas the DT50for rimsulfuron ranged from 5 to 6 days. Safe recropping intervals on soil treated with imazethapyr (rate of 35 g a.i. ha‐1) ranged from 3–4 weeks for the least sensitive species (maize, sunflower and mustard) up to 5–6 months for the most sensitive ones (sugar beet and turnip). For rimsulfuron (rate of 15 g a.i. ha‐1), recropping intervals of 2–3 weeks proved to be long enough to avoid injuries to any crops, except for the most sensitive species (turnip), which required 6 weeks before it could be safely sown in treated fields. Simple greenhouse bioassays allowed reliable predictions to be obtained about injuries observed in the field, confirming their usefulness to forecast the risk of car

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1996.tb01803.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryStrigaseeds were extracted from soils collecled in Mali and the viahility of these seeds was estimated.Strigaseeds were found in 45 of 46 samples taken from 23 fields.Siriga hermonthica(Del.) Benth. growmg on the host crop millet, was present at all 46 sites sampled. The a size uf theStrigaseedbaiik measured lo a depth of 15 cm was estimated to be 38 800 m‐2of surface area (geometnc mean 11 500). The average number ofS. hermonthicaplants observed per millei hill was 8.83 (geometric mean 3.89) or 13.98 m‐2(gcometrie mean 5.69 m‐2). Higher crop hill densities tended to result in higher densities of emergedS. hermonthicaper hill. The relationship between seeds m‐2andS. her‐monhicaplants m‐2was fitied to a reetungular hyperbola and used to reassess an existing model ofS. herniou

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1996.tb01804.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY