ISSN:0143-6147    

DOI:10.1080/09670879109371606

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Walking speed as a variable in manual spray application was investigated. Trials were conducted to evaluate people's perception of the walking speeds 0.5, 1.0 and 1.5 ms−1. The largest difference between the target speed and the speed actually walked occurred at 1.5 m s−1. although there was a large variation in actual speeds walked for each target speed. Training did not significantly improve the ability of individuals to walk at a given speed, but decreased the variation around the mean. The results are discussed in relation to the use and effect of walking speed as a parameter in manual spray application.

ISSN:0143-6147    

DOI:10.1080/09670879109371607

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Field experiment was conducted at Queimadas, Paraiba, Brazil, during the cotton season of 1987 to evaluate methodologies of the application of Cyfluthrin EC and Cypermethrin ED against cotton boll weevil(Anthonomus grandis)and pink bollworm(Pectinophora gossypiella).The results obtained showed that: (1) Cytfluthrin EC, at 15 g, 20 g and 40 g a.i./ha, applied with handoperated knapsack sprayer along every row and alternate cotton rows, and Cypermethrin ED, at 3–91 g and 7–81 g a.i./ha, applied with ElectroDyn sprayer nozzle taken along alternate and interrow space, respectively, are effective for the control of the cotton boll weevil and pink bollworm. (2) Optimum methodologies of application of Cyfluthrin EC and Cypermethrin ED to control cotton boll weevil and pink bollworm are spraying the insecticides in alternate rows and inter‐row spaces, respectively. (3) The percentage of damage loculi of boll by cotton boll weevil is not suitablé for evaluating insecticides against cotton boll weevil. (4) The decreased dosages and specific placement of the Cyfluthrin EC and Cypermethrin ED in relation to pest behaviour are important tools in programmes of cotton boll weevil and pink bollworm management.

ISSN:0143-6147    

DOI:10.1080/09670879109371608

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The use of pesticides for the control of pests and diseases of major food and cash crops, both in field and store, has increased enormously in Nigeria during the past 5–10 years. This dramatic increase in pesticide usage is predominant among some and most of the medium‐ and large‐scale farmers respectively. Due to the prohibitive costs and erratic supply of pesticides, the majority of farmers with small‐scale holdings have been adopting alternative methods of pest and disease control. Some methods involve application of neem extracts, vegetable oils, ashes, heat and smoke treatment, pepper, soap solutions, mulch and organic soil amendments. This paper reviews some of these alternatives, with reference to their efficacy and cost to small‐scale farmers in Nigeria. Inherent problems associated with their use are highlighted.

ISSN:0143-6147    

DOI:10.1080/09670879109371609

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Six seed dressing insecticides were tested for efficacy againstOphiomyia phaseoli(BF) in 1987 and 1988 at two locations in south‐central Ethiopia. Endosulfan and aldrin, at 5 g a.i./kg of seeds, were the least phytotoxic and the most effective. The rest gave variable results; BF control with some insecticides (e.g. furathiocarb) was comparable, but they showed varying degrees of phytotoxicity. The maximum seed yield loss was 36.5%. The results suggest that aldrin be replaced with endosulfan, which is less persistent.

ISSN:0143-6147    

DOI:10.1080/09670879109371610

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The neotropical weedLantana camarawas first introduced to Micronesia as an ornamental plant around the turn of the century. It quickly established and, within the space of few decades, became a problem on many of the islands there. The first attempts at biological control of lantana in this region started shortly after World War II and continued, largely on a somewhat sporadic and haphazard basis, up to recent times. However, information on the natural enemies introduced, their establishment and effectiveness, is limited and in some cases contradictory. For this reason, surveys were conducted on the major islands within the Caroline and Mariana island groups to determine the status and natural insect enemies ofL. camara.The surveys revealed that seven of the 13 species of exotic insects introduced into the area had established and achieved an acceptable level of control in the majority of cases examined. However, not all species were represented on all islands visited and, typically, some species were more effective than others. Also, the effectiveness of certain species varied between islands and between different coloured varieties of lantana.

ISSN:0143-6147    

DOI:10.1080/09670879109371611

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The mean yield data of 30 experiments conducted over large parts of India during 1982–68 revealed that efficient weed management was one of the most important production inputs in pigeonpea cultivation. The relative improvements from weed management were 31% as against 5% due to fertilizer use (18–46–0). Weed control combined with fertilizer use exhibited synergistic effects in some conditions. Further studies at Kanpur during 1986–88 revealed that monocot (narrow‐leaved) weeds caused greatest potential damage, closely followed by sedges. Dicot weeds were least harmful. A study on the relative efficacy of different herbicides in a pigeonpea/sorghum intercropping system showed that pendimethalin 1.5 kg/ha as pre‐emergence spray was the most effective herbicide followed by alachlor at 2 kg/ha or 0.75 kg/ha pendimethalin + one hand‐weeding at 30 days after sowing.

ISSN:0143-6147    

DOI:10.1080/09670879109371612

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The ecological behaviour ofCochliobolus miyabeanus(Ito et Kurib.) Drechsl. ex Dast.(Bipolaris oryzae(Breda de Haan) Shoem.), causal agent of brown spot of rice(Oryza sativaL.), was investigated in a tidal mangrove swamp at Rokupr Experimental Farm, northwestern Sierra Leone. Disease increased where transplanting was delayed. This was probably due to the coincidence of flowering with favourable environmental conditions for disease development from November to February. Nitrogen fertilization at 40kg N ha−1significantly (P= 0.05) reducedC. miyabeanusincidence in 1983, but not in 1984 and 1985 cropping seasons at the same site. Grain yields of ROK 5, a medium‐duration improved rice cultivar(ca.150 days) were significantly reduced in late‐transplanted rice crops (September to November) in spite of adequate N fertilization. Mangrove mud was not an important source ofC. miyabeanuspropagules. Incidence of leaf scald caused byMonographella albescens(Thum) Parkinson, Sivanesan and Booth(Microdochium oryzae(Hashioka and Yokogi) Samuels and Hallet) and leaf smut caused byEntyloma oryzaeMiyake were generally stimulated by N application.

ISSN:0143-6147    

DOI:10.1080/09670879109371613

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The incidence and severity of rice yellow mottle virus (RYMV) Sobemovirus group was monitored in various rice‐growing areas of West Africa. Its presence or absence was determined by symptomatology and serological tests. RYMV was found in all the rice environments but at different levels of incidence and severity of the disease which appeared to depend on the type of variety planted, the rice environment and vegetation zones. Graminaceous weeds, including some wild rice species, were confirmed as alternative hosts for RYMV. Twenty‐five rice cultivars comprising local and locally developed cultivars were resistant to RYMV. Most of these cultivars showed stable resistance to rice blast(Pyricularia oryzae(Cavara). The occurrence of RYMV symptoms on some uninoculated plants indicated the possibility of the virus being transmitted either by the beetle vector or through being carried on the seed.

ISSN:0143-6147    

DOI:10.1080/09670879109371614

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Increasing yield of cowpea by 30–90% is possible in Senegal when the crop is sprayed once or twice in order to control flower thrips. Therefore it appears necessary to determine the action threshold for the dominant species of flower thrips,Megalurothrips sjostedtiTryb. Eight and 22 thrips per 25 flower buds (at Nioro and Bambey respectively) and 150 thrips per 25 flowers were determined as the action threshold where a minimum of two sprays is needed. When only one spray is necessary during the flowering period, 90 thrips per 25 flowers is the suggested action threshold to protect flower buds as well as flowers from thrips attacks.

ISSN:0143-6147    

DOI:10.1080/09670879109371615

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor