摘要:

Pragmatic thresholds for control actions against pests of farm‐stored maize in Africa have been exceeded following the recent introduction ofProstephanus truncatus.Current control programmes, based largely upon insecticide admixture with shelled grain, are achieving some success but the development of cost‐effective, fully integrated pest‐management programmes, that can be maintained in the long‐term, requires further research in the following areas: infestation sources and dispersal; agro‐climatic factors affecting pest status; socio‐economic factors affecting the long‐term cost‐effectiveness of control programmes; and alternative measures, including physical and biological control strategies as well as alternative grain protectants and application techniques. Specific objectives, within these areas, are indicated and discussed against the background of existing knowledge and current concepts of stored‐product insect control. In conclusion, interacting factors for research and analysis are drawn together in a synoptic chart and key issues are identified.

ISSN:0143-6147    

DOI:10.1080/09670878809371226

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

More than 10 000 ha of roosts and nesting colonies of quelea are sprayed with avicides every year in Africa. The avicide the most frequently utilized is Queletox. Since 1959 the dose of avicides has decreased from 5.5–39 kg a.i. to 0.6–2.4 kg a.i. per ha. The droplet diameter decreased from 250 to 50–150 microns. However, to avoid contamination of the environment and ensure a rapid mortality of quelea it is recommended to use the doses between 2.5 and 4 kg of a.i. per ha. Spraying of avicides should be done in the evening when all quelea are in the site. The dose should be so high that the sprayed birds die during the night and within the limits of the sprayed area. The droplet diameter should be chosen according to the weather conditions during spraying so as to reduce the drift of avicides. Spraying of sites containing non‐target species should be prohibited. More studies are necessary about the impact of spraying on the non‐target species. It appears also that the avicides presently used are too persistent after spraying, and act too slowly on quelea. Further optimization of the dose of avicides and droplet diameter will be possible if more data are available on droplets, the impaction efficiency, the body capturing surface and mode of intoxication. More data are also necessary on quelea behaviour during and after spraying.

ISSN:0143-6147    

DOI:10.1080/09670878809371227

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The reproductive biology and the population structure ofBandicota bengalensiswas studied from a regular monthly collection, made in the Paddy fields around Bangalore, Karnataka from 1982 to 1984. The bandicoot exhibits a seasonal reproductive activity lasting from early August till the end of April with an anoestrous period between March and July. Correlatively, the reproductive glands and the sex accessories show seasonal changes in their weights. The peak reproductive activity was seen during September, October and November, when the prevalence of pregnancy was 0.81 with a mean litter size of 7.1. Analysis of data compared with temperature and rainfall showed that variation in breeding activity could be due to rainfall and the availability of food in the environment. The annual reproductive rate is calculated to be 67 young per female per breeding season. The bandicoots exhibit lesser body weights during summer months, and greater body weight coincides with the peak breeding season when the paddy crop is maturing. It is suggested that May, June and July are the best months for the initiation of control measures against this major rodent pest species, when their populations are at a minimum (reproductively inactive) to achieve economic and effective results.

ISSN:0143-6147    

DOI:10.1080/09670878809371228

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Root knot nematodes(Meloidogynespp) are a serious problem of vegetable production in Tanzania and feasible control methods are lacking. In this study, marigold plants(Tagetes minutaandT. erectawere compared to nematicides ethylene dibromide and aldicarb for control of root knot nematodes. Of the three, ethylene dibromide gave the most effective reduction of root galling and the poorest shoot growth and fruit yields, aldicarb gave the highest shoot growth and fruit yields and reduced the number of root galls by a factor of 21 in glasshouse conditions.Tagetes erectaand T.minutareduced the number of galls by a factor of 4 and 6 respectively over the non‐treated controls. Similar results were observed in field conditions. There was a negative correlation between the reduction in number of root galls and the Increase in plant growth or fruit yields in treatments with aldicarb and marigold plants, but not in treatments with ethylene dibromide. This indicated phytotoxic effects of ethylene dibromide.

ISSN:0143-6147    

DOI:10.1080/09670878809371229

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The flow rate of a formulation through hand‐held u.l.v. equipment is determined by the viscosity of the product and the diameter of the restrictor orifice fitted. A convenient flow rate onto the atomiser head is 1 ml s−1. Most hand‐held u.l.v. equipment is supplied with several interchangeable restrictors allowing the spray operator to choose one suitable for the formulation to be applied. The flow rates of four blank (containing no pesticide) u.l.v. formulations, each of different viscosity, through five different pieces of application equipment were investigated. The results are tabulated so that the spray operator can choose an appropriate restrictor to fit to the hand‐held u.l.v. equipment he wishes to use. To use this information the operator must know the viscosity of the product at the temperature he intends to spray at It should be emphasised that the results presented in no way eliminate the need for a calibration run before commencing spraying.

ISSN:0143-6147    

DOI:10.1080/09670878809371230

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Field study was conducted to study the magnitude of foltap residues in betelvine leaves. Betel leaves were treated with foltap (80% W. P.) at 1.6 kg and 3.2 kg a.i./ha and four sprayings were done at the interval of 15 days. The samples of betel leaves were drawn at different time intervals and analysed by gas chromatography, after necessary extraction and cleanup. It was found that the initial residues of foltap varied from 35.0–40.0 ppm which dissipated to 7.0–9.2 ppm in betel leaves even after 14 days of each application at the recommended dose (1.6 kg. a.i./hac). It was also revealed that after thorough washing with water, the foltap residue remains at 0.23 ppm 14 days even after the fourth spraying at the recommended dose, which is above the recommended ADI value.

ISSN:0143-6147    

DOI:10.1080/09670878809371231

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Three fungal diseases; damping‐off, powdery mildew and Choanephora fruit rot, were found to occur on vegetable marrow throughout the year, in the southern region of Oman (Dhofar), causing considerable damage. The percentage of infection of damping‐off was reduced by seed dressing, using Fernasan D (25% thiram + 20% gamma‐HCH) at a rate of 3 g/kg seeds. Seven fungicides were used to control both powdery mildew and Choanephora fruit rot. Benomyl, thiabendazole, ethirimol and dinocap were highly effective against powdery mildew. Mancozeb, dinocap and thiabendazole reduced the infection of Choanephora fruit rot.

ISSN:0143-6147    

DOI:10.1080/09670878809371232

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The disease control efficacy of four commonly recommended fungicides: carbendazim (Bavistin, 50 w.p.), carboxin (Vitavax, 75 w.p.) quintozene (Brassicol, 75 w.p.) and thiram (Thiride, 75 w.p.) used as seed treatment, pre‐ and post‐sowing soil drench and seed treatment plus soil drench were tested against wilt and root rot diseases of cotton in multiple sick plots having four soil pathogen:Fusarium oxysporumsp.vasinfectum(Atk.) Snyder and Hansen,Macrophomina phaseolina(Tassi) Goid=Rhizoctonia bataticola(Taub.) Butler,Rhizoctonia solani(Kühn) andFusarium solani(Mart.) Sacc. It was observed that seed treatment or soil application of carbendazim followed by carboxin gave good disease control against pre‐ and post‐ emergence seedling mortality. Pre‐sowing soil drench of test fungicides provided better disease control compared to post‐sowing soil drench. No significant differences in disease control was noted when the test chemicals were used either as seed treatment + pre‐sowing soil drench or seed treatment + post‐sowing soil drench except in carboxin which gave relatively better disease control when used as seed treatment + pre‐sowing soil drench. It is suggested that seed treatment or pre‐sowing soil drench with carbendazim or carboxin could be used to reduce seedling mortality of cotton due to individual or combined infections ofFusarium, MacrophominaandRhizoctoniaspp.

ISSN:0143-6147    

DOI:10.1080/09670878809371233

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A survey carried out in 1984 showedStriga hermonthica(Del.) Benth. to be widespread and severely infesting sorghum, millets and maize. About 75% of 700 fields covered were infected at an average rate of 1–2 shoots per m2. Maize was the least attacked cereal followed by early millet, late millet and sorghum, in order of increasing attack. The best traditional cropping system with regard to reducingStrigapopulations was to rotate early millet and groundnuts over a single season, allowing cattle to graze the cereal stubble and then tethering them in the field at night during the off‐season. There was no direct relationship between rainfall and temperatures and density ofStriga.

ISSN:0143-6147    

DOI:10.1080/09670878809371234

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Sixty‐four cattle of the Kenana Dreed were exposed to natural tick challenge near Abu Naama (450 km south of Khartoum) for 121 days. Thirty‐three of these were treated with acaricide which reduced theirAmblyomma lepidummean adult tick burdens to 3.9 animal. The untreated 31 animals averaged 47 Alepidumadults/animal. During the course of the experiment the treated group achieved a liveweight gain of 13.1 kg (108g/day) whereas the untreated group gained 11.5 kg (95 g/day); the difference between groups was nonsignificant Other tick damage effects are discussed to assess the economic benefits of tick control.

ISSN:0143-6147    

DOI:10.1080/09670878809371235

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor