摘要:

AnAscochytasp. was consistently isolated from ascochyta blight‐affected lentil (Lens culinarisMedik.) seed and plants. The fungus was pathogenic only to lentil and not to any of seven other legume species tested. Based on the cultural and morphological characteristics, pathogenicity and host range tests the causal fungus was identified asAscochyta lentisVassilievsky. The symptoms of the disease on lentil leaves, stems and pods are necrotic lesion speckled with brownish pycnidia. The seed‐borne nature of the fungus was confirmed. In a 3‐year field trial, chlorothalonil (Bravo 500), benomyl (Benlate) and a mixture of tridemorph and maneb (Calixin M) provided the best disease control and highest yields. The hot‐water and dry‐heat treatments at 55°C for 25 min and 70°C for 24 h gave partial inhibited fungal growth from seed. None of the 139 accessions tested was immune; 35 were identified as resistant, whereas the remainder were moderately resistant to susceptible. Seed transmission of the fungus varied in different genotypes according to their resistance reaction.

ISSN:0143-6147    

DOI:10.1080/09670879109371616

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Out of 12 fungi isolated fromSclerotiniainfested soils of pea fields, seven—viz Penicillium cyclopium, Paecilomyces lilaci‐nus, Aspergillus niger, Aspergillus fumigatus, Acremonium implicatum, Penicillium sheariandTrichothecium roseum—were found antagonistic toSclerotinia sclerotiorumthe cause of white mould of peas.Trichoderma harzianumwas found to parasitize the mycelium and sclerotia of S.sclerotiorumand destroyed the sclerotia within 15 days.Trichothecium roseumgave 100% inhibition of sclerotial germination, after 30 days of co‐incubation in soil. Application of wheat bran culture ofT. harzianumunder field conditions gave significant control of the disease plus a yield increase. Mycelial preparation of T.harzianumwas more effective in comparison to spore preparation.

ISSN:0143-6147    

DOI:10.1080/09670879109371617

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The fruit tree mealybugRastrococcus invadensWilliams, accidentally introduced into the West African region in the early 1980s, has been the subject of a successful biological control programme in Togo and elsewhere in West Africa. It is now kept at low population densities by the introduced specific parasitoidGyranusoidea tebygiNoyes. The sociological and economic impact of this successful biological control programme is evaluated. The economic assessment strongly suggests that the programme was very cost‐effective. In addition, substantial non‐quantifiable social and cultural benefits can be recorded.

ISSN:0143-6147    

DOI:10.1080/09670879109371618

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The biology and host specificity of the beetle,Gastrophysa atrocyaneaMotch were studied in the laboratory in Nanchang, China. This univoltine insect completed its immature stage in 32–39 days with adult overwintering in soil. A total of 35 plant species from 21 families were tested. Both larvae and adults attackedRumex japonicusandRumex acetosawithR. japonicusthe main host. Larvae also attacked twoPolygonumspecies,P. hydropiperandP. perfoliatum.But the adults are not concurrent with the twoPolygonumspecies. Though oviposition occurred on five other plant species, none of them supported larval development. Field observations showed thatG. atrocyanaecaused a progressive decline in naturalR. japonicuspopulations. Thus it is recommended as a valuable biological agent for this weed.

ISSN:0143-6147    

DOI:10.1080/09670879109371619

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The coccinellid beetle(Chilocorus nigritus[Fabricius], Coccinellidae: Coleoptera) was successfully introduced from India during 1985, as a biocontrol agent against the coconut scale insect(Aspidiotus destructorSign, Diaspididae: Homoptera) which infests coconut palms in south Oman. A total of 683 adults ofC. nigrituswere released during January to April 1985. The data obtained show the rapid build‐up of the predators and the subsequent decline in the host population. After 24 months from the last release (April 1985) the median number of coconut scale insects per leaf area decreased to the minimum number, since it ranged between zero and 49.7 scales, while it ranged between 174.8 and 285.0 scales before release of the predator. The coccinellid predator(C. nigritus)rapidly built up in the release site and up to 12 km distant after 6 months from the last release, since it ranged between 38.2 and 144.5 predators (adults and larvae combined) per palm. In Taqa locality, which is about 16 km from the release site, the predator appeared and was recovered after 18 months from the last release. Thus, the use of pesticides against this pest is no longer needed in the southern region of Oman. The potential danger of the studied pest, coconut scale insect(A. destructor)was greatly reduced in the release site, and in all locations under investigation all over Dhofar plain after 24 months from the last release as a result of predation of the newly established coccinellid beetle(C. nigritus)which was an efficient predator against this pest.

ISSN:0143-6147    

DOI:10.1080/09670879109371620

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Greenhouse and field experiments were conducted to study the preference of two scarabaeid beetles,Anomala cupripesHope andA. expansaBates, for soybean plants at various growth stages and the potential use of a trap cultivar to control these pests. Insects preferred to feed on 6–9‐week‐old plants compared to younger ones. This may be due to more foliage on the older plants, which is a source of food and a shelter for the insect from direct sunlight. Planting a cultivar with more foliage as a trap cultivar between rows of the agronomic cultivar attracted the beetles and reduced the infestation of the agronomic cultivar. The optimum distance to plant such a trap cultivar between rows of agronomic cultivar needs to be determined for each location.

ISSN:0143-6147    

DOI:10.1080/09670879109371621

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Ten cowpea cultivars were evaluated for their resistance toClavigralla tomentosicollisStal. in the screenhouse and in mesh cages, then seeds were analysed in the laboratory for concentration of sugar, crude protein and tannic acid. A general correlation of the resistant parameters examined and the chemical composition of the cultivars showed a positive relationship between the crude protein content and the resistance of the cultivars to the bug. The significance of these correlations is discussed.

ISSN:0143-6147    

DOI:10.1080/09670879109371622

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Fishmeal powder was formultaed with three different insecticides: fenthion 80 EC, quinalphos 40 EC and propoxur 1% W/W at 0.5% (volume/wt of fishmeal) along with 2–3% starch. The resultant formulations tested against fishmeal powder alone for the relative attraction to sorghum shootfly,Atherigona soccataRond, showed that the propoxur formulation attracted significantly more adult shootflies than the others. Use of this formulation in control resulted in a significant reduction in damage.

ISSN:0143-6147    

DOI:10.1080/09670879109371623

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The economic threshold level for the green semilooper,Chrysodeixis acuta(Walker) (Lepidoptera: Noctuidae) was determined on soybean cultivar JS 72–44 during 1986 in Madhya Pradesh, India. With an increase of every 1 larva/mrl (meter row length) at 45 d.a.e. (days after emergence) (flower initiation stage) and at 66 d.a.e. (pod filling stage), there were reductions of 593 and 662 kg/ha in grain yield, respectively. The yield loss caused by 3 to 18 larvae/mrl at flower initiation ranged from 7.29% to 45.51%, and that at pod filling ranged 9.43% to 46.49%. The control measures should be adopted at economic threshold level of three larvae and 2 larvae/mrl at flower initiation and pod filling stage of the crop, respectively.

ISSN:0143-6147    

DOI:10.1080/09670879109371624

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Coelaenomenodera minutaUhlmann is one of the major pests of the oil palm,Elaeis gulneensisJacq, in West and Central Africa. An epidemic by this leaf miner pest reduces oil palm yields by as much as 30%. A leaf miner outbreak on oil palms at Lobe (Cameroon) was first recorded in 1972. Since then over $US200 000 were spent annually on insecticides to eradicate the pest, but it was never brought under permanent control. Results indicate that leaf miner parasites were either rare or missing, and that the fauna of theCrematogasterspecies was very poor. These findings led to the conclusion that the natural enemies of the pest were under pressure of insecticides. The deployment ofCrematogasterspecies led to a decline of the leaf miner pest population in all treated fields. The reduction in the pest population was mainly due to the destruction of the larval galleries resulting in the exposure of larvae to unfavourable temperatures, heavy rains and attacks by parasites and predators. A system for monitoring and keeping the pest population below threshold level by the use ofCrematogasterspecies proved effective, and it is recommended in young palm plantings even in areas where the pest is endemic. This control method will lead to significant cash savings and the preservation of the environment.

ISSN:0143-6147    

DOI:10.1080/09670879109371625

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor