摘要:

Host‐plant resistance in conjunction with natural enemies and cultural practices should form the backbone of future pest control programmes. Sources of resistance toAtherigona soccataRond.,Chilo partellusSwin. andContarinia sorghicolaCoq. have been identified. Efforts should be made to incorporate resistance into plants with good agronomic background and to strengthen the level of resistance. Resistance to pests and grain yield should be given equal consideration in the development and release of new cultivars. Cultivars with loose panicles may be developed for areas endemic to head bugs and head caterpillars. Pest avoidance through timely planting as decided by pest‐population dynamics and rainfall patterns, balanced fertilizer application, clean cultivation, and proper crop combinations should be popularized among the farmers to reduce crop losses. Readily available and inexpensive insecticides may be used as and when necessary based on economic thresholds.

ISSN:0143-6147    

DOI:10.1080/09670878509370977

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Flower shedding in summer mungbean,Vigna radiata(L.) Wilczek, is a common feature caused by thrips,Megalurothrips distalis(Karny). Eleven insecticides were tested in field trials for the control of thrips during the period 1982 to 1984. All the treatments were significantly better in controlling the thrips, reducing flower shedding, increasing the pod numbers and grain yield, in comparison with the control. Increases in yield compared with the control during trials ranged from 85 to 89% (1982), 26 to 96% (1983) and 5 to 194% (1984). Dimethoate gave the highest increases in yield and profit followed by monocrotophos and endosulfan.

ISSN:0143-6147    

DOI:10.1080/09670878509370978

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Field trials were carried out in Malawi with (Z)‐8‐dodecenyl acetate and a 1: 1 mixture of (Z)‐8‐dodecenyl acetate and (E)‐8‐dodecenyl acetate, which were previously identified as the female sex pheromones ofCryptophlebia batrachopaMeyrick andC. leucotretaMeyrick (Lepidoptera: Tortricidae) respectively. Catches of male moths in cardboard sticky delta traps baited with the respective pheromones were highly significantly correlated with knock‐down counts for each species. Polyethylene vials were shown to be more effective dispensers for the pheromones than rubber septa. An initial pheromone loading of 1·0 mg was as effective as 5·0 mg and significantly more effective than 0·1 mg when assessed over 4‐week periods. The experiment suggested that vials impregnated with 1·0 mg of pheromone started to lose their attractiveness after about 6 weeks and were virtually unattractive after 12 weeks in the field.

ISSN:0143-6147    

DOI:10.1080/09670878509370979

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Pathogenic micro‐organisms isolated from West African grasshoppers (Acrididae) included entomopoxviruses, protozoa, fungi, and a rickettsia. Entomopoxviruses were isolated fromCataloipus fuscocoerulipes(Krauss),C. cymbiferus(Krauss),Oedaleus senegalensis(Krauss),O. nigeriensisUvarov,Krassaria angulifera(Krauss) andHeteracris annulosus(Walker). Two species of microsporidia (Protozoa) were isolated fromAcorypha glaucopsis(Walker),K. angulifera, O. senegalensis, O. nigeriensis, Hieroglyphus daganensisKrauss andAcrida bicolor(Thunberg). The amoebic protozoanMalameba locustae(King & Taylor) was observed inO. senegalensisandDiabolocatantops axillaris(Thunberg). A yeast‐type fungus, observed inO. senegalensisand an undeterminedAnacridiumsp., was isolated fromAiolopus thalassinus(Fab.), A rickettsia was isolated fromZonocerus variegatus(L.).

ISSN:0143-6147    

DOI:10.1080/09670878509370980

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Psara bipunctalisF. (Lepidoptera. Pyralidae) has been identified as a serious defoliating insect pest ofAmaranthus cruentusin the southern part of Nigeria. A brief life cycle study carried out at ambient temperature of 28 C showed four different larval instars with pre‐pupal and pupal stages all lasting between 21 and 22 days. Three concentrations of primiphos‐methyl were evaluated for the control ofP. bipunctalisin the field. Pirimiphos‐methyl at 0.57 kg/ha a.i. gave the optimal control of this defoliator.

ISSN:0143-6147    

DOI:10.1080/09670878509370981

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Factors affecting the performance of acaricides in the control of ticks are reviewed. A survey of studies on the deposition of acaricides on the hair of dipped or sprayed cattle shows that acaricides in suspension form metastable systems. Their physical instability is initiated or accelerated by additives, ageing, fouling and replenishment and is manifested as marked changes in the size of the deposit. Greater changes occur in suspensions produced by emulsion and melt‐type formulations, than in those produced from wettable powder type formulations. The method of application—whether by dipping or spraying—and the breed of cattle used, also cause changes in deposition. It is concluded that the requirements for an optimal formulation for tick control could best be met by a flowable paste. Insolation resulting in decreased persistence of deposits is seen as the reason for the shorter protection against infesting ticks observed in summer. Fouling was responsible for most of the chemical decomposition which occurred in five of the acaricides studied.

ISSN:0143-6147    

DOI:10.1080/09670878509370982

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Ticks from cattle were collected for the purposes of quantifying the number of tick species and their relative abundance at Msekera Regional Research Station. Fifteen species were recorded. It was found that although different species of ticks parasitized cattle throughout the year, their peaks of abundance were dependent on the season. The majority of the species had their peaks during the wet season (November to April).Rhipicephalus punctatus(Warburton) was found to be the most abundant species followed byRhipicephalus appendiculatus(Neumann) andAmblyomma variegatum(Fabricius).Haemaphysalis leachi(Audouin) andRhipicephalus turanicus(Morel and Vassileades) were least abundant. The findings are discussed in relation to seasonal vector abundance and disease transmission, the problems of chemical control of a multi‐species tick population and climatic influence on general tick population dynamics.

ISSN:0143-6147    

DOI:10.1080/09670878509370983

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A survey conducted during 1979–81 in Bangladesh revealed 20 rice diseases, including two viral, two bacterial, 13 fungal, two nematode and one micronutrient deficiency problem. Of these diseases. 16 appeared as major during the period under report. The number of diseases were 17, 16 and 16 during theBoro. Ausand transplantAmanseasons, respectively, with 12 common in all three seasons. Thirteen diseases including bacterial blight, bacterial leaf streak, sheath blight, sheath rot, blast, brown spot, grain spot, stem rot and leaf scald were classified as major; and tungro, bakanae, cercospora leaf spot and zinc‐deficiency were classified as either major or minor, and were common to all regions. Diseases not common in all regions were stack burn, root knot, and ufra classified as major or minor, and false smut, seedling blight. Yellow dwarf and damping off which were always classified as minor. Diseases which were typical forBoro. Ausand transplantAmanseasons were seedling blight and damping off. Yellow dwarf, and false smut respectively.Austhe most humid and warmest season, and the coastal humid areas experienced more major diseases. Seasonal and regional differences in the disease incidence appeared related to agro‐climatic variations.

ISSN:0143-6147    

DOI:10.1080/09670878509370984

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Biochemical and pathogenicity studies of bacterial isolates from onions with discoloured internal tissues indicated the fluorescent pseudomonadPseudomonas aeruginosa(Schroeter, 1872) Migula, 1900 to be the causal agent and that a site of injury was necessary for infection to take place. It is postulated that in the field a likely mode of infection would be through the necks of onion bulbs which are damaged during or after harvest.

ISSN:0143-6147    

DOI:10.1080/09670878509370985

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0143-6147    

DOI:10.1080/09670878509370986

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor