ISSN:0143-6147    

DOI:10.1080/09670878909371308

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Field investigations carried out in two winter seasons of 1984–85 and 1985–86 on clay‐loam soil at the Central Institute of Medicinal and Aromatic Plants, Regional Centre, Pantnagar, Naintial, India revealed that unrestricted weed growth reduced the seed and oil yields of Bulgarian coriander(Coriandrum sativumL. cv. S 33) by 40.3 and 37.0%, respectively. Applications of pendimethalin and fluchloralin at 0.75 and 1.00 kg a.i./ha, respectively causing 76.5 and 71.9% weed control, were most promising treatments, and gave seed and oil yields comparable to weed‐free check. Applications of oxadiazon at 0.25–0.75 kg a.i./ha and propanil at 1–2 kg a.i./ ha, although proved selective but failed to produce desired results. None of the treatments impaired the quality of coriander seed oil, measured in terms of d‐linalool content.

ISSN:0143-6147    

DOI:10.1080/09670878909371309

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Two morphological variants ofEchinochloa crus‐galliwere collected from rice fields of an area in Greece where rice has been grown for over a decade and growers have recently been complaining about reduced effectiveness of propanil. Seedling response of the two variants to propanil was compared with that ofE. crus‐gallicollected from vegetable fields in another area where rice has never been grown. Initial contact toxicity of propanil was similar in all collections. Growth inhibition thereafter was clearly different, resulting in death of theE. crus‐gallifrom vegetables but not of theE. crus‐gallifrom rice. The latter could overcome initial toxicity and resume growth at 8 kg/ha of propanil, whereas the former was killed at 2–4 kg/ha. Prevalence ofE. crus‐galliforms of higher tolerance resulting from selection through rice husbandry and/or repeated use of propanil may account for the reduced effectiveness of propanil in the area of intensive rice growing.

ISSN:0143-6147    

DOI:10.1080/09670878909371310

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

There was little difference in the weed flora between transplanted and wet‐seeded rice(Oryza sativaL.). The weed control methods used greatly influenced the weed flora.Echinochloa glabrescensMunro ex Hook.f. was dominant in the unweeded and herbicide‐treated plots whileMonochoria vaginalis(Burm. f.) Presi was dominant in the hand weeded plots. Weed weights were similar in both planting methods. Weed weight was reduced and rice yield was increased by hand weeding and herbicide treatments but the efficiency of weed control with herbicides decreased due to the buildup of weeds in the later plantings.

ISSN:0143-6147    

DOI:10.1080/09670878909371311

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Imperata cylindricais one of the most noxious weeds in South East Asia. Over the past two decades significant advances have been made in the understanding of its biology and control. This paper reviews work over this period and concludes that despite such advances, there remains much scope for improvement of control, particularly in development of methods appropriate for small scale farmers with limited resources.

ISSN:0143-6147    

DOI:10.1080/09670878909371312

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Weed species and densities of weeds present on the wheat farms at the Hanang plains in northern Tanzania were surveyed just before wheat harvest in May, 1986. The dominant weed wasSetariaspp. mainly,Setaria verticillata(L.) Beauv., which occurred at an average density of 58 shoots/m2. Additional weed species which occurred at average densities of greater than 1 plant/m2wereAmaranthusspp., mainlyAmaranthus retroflexusL., andGalinsoga parvifloraCav. The density ofSetariaspp. was greatest on the farms where wheat had been grown for the longest periods of time (18 and 10 yr). The densities of the other weed species on the Hanang wheat farms were not influenced by the number of years (1–18 yr) that wheat has been grown in monoculture. Several weeds were identified that are resistant to 2,4‐D, which is currently used for broadleaf weed control, but there was no indication that these weeds were becoming a serious problem.

ISSN:0143-6147    

DOI:10.1080/09670878909371313

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Field surveys during the 1986–87 growing season throughout the West Bank and part of the Gaza Strip concentrated on the distribution, ecology, hosts and control of the parasitic generaOrobanche(broomrape),Cuscuta(dodder), andViscum(mistletoe). The most widespread parasitic weed isOrobanche ramosawhich can attack a great diversity of hosts but is most damaging on tomato, potato, and lettuce.Orobanche crenataheavily damages broad‐bean. Control ofOrobancheon large farms is almost exclusively by application of methyl bromide while small farmers attempt control with hand weeding.Cuscuta pedicellatais frequently found in lentils andVicia sativaa widely grown fodder crop.Viscum cruciatummay be locally damaging to olive and almond but attacks a diversity of hosts. To our knowledge, this is the first survey of parasitic weeds in the West Bank and Gaza Strip.

ISSN:0143-6147    

DOI:10.1080/09670878909371314

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A field experiment was performed to determine the effects of different times and frequencies of handweeding on grain yields in upland rice. Five weeding treatments were done. These treatments consisted of single weedings at 20 and 35 days after emergence (d.a.e.) and double weedings at 10 and 15 d.a.e., 20 and 35 d.a.e. and 30 and 45 d.a.e. Two controls were made: a weed‐free control where weeds were continuously removed and a weedy control where no handweeding was done. Aboveground destructive harvests on the controls were used to determine dry matter partitioning. These were performed at 10, 30, 50, 70 and 90 d.a.e. and at harvest. Rice and weed heights were measured for the controls and all treatments. Grain yields were compared and analyzed statistically. Absence of weed control produced only 50 kg/ha of grain. Single weeding increased yield to about 2000 kg/ ha and double weeding to about 2500 kg/ha. However, no significant differences were found between treatments of the same weeding frequency. Complete weed control produced 3000 kg/ha of grain. During grain formation, stem weight of weed‐free rice declined by 24% as compared to 74% in weedy rice.

ISSN:0143-6147    

DOI:10.1080/09670878909371315

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Different cultural practicesviz.burning, sun‐drying of the stubbles, formaldehyde treatment of the soil and flooding were tried to control stem‐rot disease of rice incited byMagnaporthe salvinii(Catt.) Krause and Webster(Sclerotium oryzaeCatt.) for six consecutive seasons both summer and winter from 1980–82. The burning of straw and stubbles was the best of all cultural treatments and reduced the severity of the stem‐rot of rice by about 85% over the control (untreated soil). Formaldehyde solution (2%) treatment also reduced the incidence of the disease to an extent of 54% over the control.

ISSN:0143-6147    

DOI:10.1080/09670878909371316

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Six wettable powder insecticides, acephate, bendiocarb, carbaryl, isoprocarb, DDT and BHC and one flowable insecticide, carbofuran (F) were tested under greenhouse as well as under field conditions in order to know their efficacy in reducing rice tungro disease incidence. Acephate, bendiocarb, carbaryl, isoprocarb and carbofuran (F) not only prevented tungro infection in artificial inoculation tests in the rice cultivar Taichung Native 1, but also efficiently managed the disease incidence under field conditions in two rice cultivars Taichung Native 1 (susceptible) and Ratna (tolerant). They reduced the rate of tungro infection in both cultivars as compared to control. The vector population was remarkably reduced by these insecticides compared to DDT, BHC and control. The plant height, panicle number, grain yields and dry straw weight were significantly superior in the plots treated with acephate, bendiocarb, carbaryl, isoprocarb and carbofuran (F) in comparison to control. There was a strong negative correlation between the tungro infection and height, panicle numbers, grain yield and dry straw weight and a positive correlation between vector population and the rate of tungro infection.

ISSN:0143-6147    

DOI:10.1080/09670878909371317

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor