摘要:

Among the various intercrops in the oil‐palm‐based agroforestry system, only cacao shared a common pest complex with oil palm. Insect pests of other intercrops such as Albizzia, Ailanthus, Casuarina and Subabul are host‐specific and do not infest oil palm. No pest incidence was noticed in Eucalyptus and Australian black wood.

ISSN:0143-6147    

DOI:10.1080/09670879109371536

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Despite high social and economic costs resulting from pesticide use, farmers in many developing countries still persist in this method of pest control. One reason is the perception that the development and implementation of IPM strategies are beyond their capabilities. Using the example of cabbage and tomato production in Trinidad, insecticide use was calculated at above 40.0% and 100.0% respectively of recommended rates, despite the introduction of parasitoids for cabbage pest control and reports that fruit‐ and leaf‐feeding tomato pests may not cause serious yield loss. An IPM strategy for these crops is suggested based on increased research, including alternatives to pesticides, improved application technology and pest monitoring, together with a strong extension capability.

ISSN:0143-6147    

DOI:10.1080/09670879109371537

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The area of coconut leaflets was estimated with multiple‐regression equations using parameters such as frond length, width of the leaflets and the area of corresponding leaflets from the youngest frond, which is usually undamaged. The error of one estimate was commonly less than 10% provided enough parameters were available. Measuring the area of leaflets reduced by leaffeeding insects with a leaf‐area meter, and comparing it with the above results, gave estimates on the defoliation level. Examples for damage caused bySexavaspp. are given and discussed.

ISSN:0143-6147    

DOI:10.1080/09670879109371538

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The advantages of an economic threshold system for the cotton jassid,Amrasca biguttula(Shir) and the spotted bollworm,Earias vittella(F.) on cotton were evaluated. Two years’ results revealed that under recommended and currently followed practice (schedule spray system), six to eight insecticidal sprays were required to control the cotton jassid and the spotted bollworm, while following an economic threshold system, only one or two insecticidal sprays were required to keep their populations within tolerable limits. The amounts of insecticide and their application costs in the schedule spray system were much higher than in the economic threshold system, but the yield variations of seed cotton between these treatments were statistically insignificant. The benefit:cost ratios were much higher in the economic threshold system than the schedule spray system for both years.

ISSN:0143-6147    

DOI:10.1080/09670879109371539

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Survey questionnaires were administered in three locations in Nigeria to gain an insight into cowpea farming practices with emphasis on insect pest control. The objective of the survey was to obtain guidance for the development of integrated pest management (IPM) strategies catering for all categories of cowpea growers. The survey revealed that cowpea as grown at present is mostly as a secondary crop requiring low inputs to boost its production. Therefore, a rational pest control approach should be integrative, locale‐specific and include: (1) educating farmers on control tactics, (2) identifying and developing effective IPM strategies that are low cost and which are scale neutral, and (3) creating an awareness on the necessity for IPM inputs to be readily available and affordable.

ISSN:0143-6147    

DOI:10.1080/09670879109371540

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The population dynamics ofDiaphania indica(Saunders) (Lepidoptera: Pyralidae) was studied using partial life‐tables. The study revealed that April‐September was the peak period of incidence of the pest while November‐February was the lowest. The biotic mortality factors recorded in the present study were parasitism by the following:Apanteles taragamaeViereck,A. machaeralisWilkinson (Hymenoptera: Braconidae),Goniozus sensoriusGordh (Hym: Bethylidae),Trathala flavoorbitalis(Cam.) (Hym: Ichneumonidae),Elasmus brevicornisGahan (Hym: Elasmidae) andPhanerotoma hendecasisellaCam. (Hym: Braconidae). Among these,A. taragamaewas the key mortality factor ofD. indica.The study also revealed that only two of the six parasites exercised an important role in the population dynamics ofD. indica.The combined action of these two parasites from January to March and October to December was significant in keeping the population index lower than during the months when these parasites were absent.

ISSN:0143-6147    

DOI:10.1080/09670879109371541

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The level of Incidence of the coconut rhinoceros beetle,Oryctes rhinocerosL. and the damage caused to the coconut palms by them in the Andaman and Nicobar Islands were studied. The Andaman Group recorded an average of 61–9% beetle incidence, 53.1% and 52.1% frond and crown damage, respectively. The Nicobar Group registered 37.6% beetle incidence, 17.2% and 21.4% frond and crown damage, respectively. A high and significant correlation was found between the beetle population and average annual rainfall (r = 0.876,P <0.001). The other major climatic and non‐climatic factors that contribute to the high level incidence of the beetles and the palm damage in the islands are reported here.

ISSN:0143-6147    

DOI:10.1080/09670879109371542

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Results from two sets of field experiments carried out during 1984 and 1985 revealed that Japanese mint(Mentha arvensisL.) was associated with both broad‐leaf and grass weeds dominant in summer and rainy seasons representing the period of first and second harvests, respectively. The weed biomass exceeded that of the crop from the very beginning of the crop cycle, and the most rapid increase in weed biomass was noted between 30 and 45 days after planting in first harvest and the first 45 days in second harvest. Unrestricted weed growth significantly reduced Japanese mint oil yield by 74.4% and 70.0%, respectively in first and second harvests. The critical period of weed interference was between 30 and 75 days in first harvest and 15 and 45 days in second harvest. Weed infestation during the critical periods caused significant reduction in plant height and herb and oil yields, and weed infestation beyond the critical periods did not have any significant influence on these parameters. The leaf:stem ratio and oil concentration in herb was also reduced significantly due to weed infestation; the oil quality in respect of menthol content, however, was not affected. Reduction in crop biomass was highly correlated with weed biomass.

ISSN:0143-6147    

DOI:10.1080/09670879109371543

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Field experiments were conducted at the Irrigation Research Station, Kadawa in the Sudan savanna zone of Nigeria during the 1984 and 1985 dry seasons to identify selective pre‐emergence herbicide mixtures for weed control in two varieties of okra(Abelmoschus esculentusL. Moench). The variety of okra only had a significant effect on crop vigour score at 6 weeks after sowing in 1985 when var. V35 was more vigorous than TAE‐38. In 1984, despite supplementary hoe‐weeding at 6 weeks after sowing, all the herbicide treatments resulted in significantly lower fruit yield than the hoe‐weeded control. Among the herbicide treatments, metolachlor plus prometryne at 2.0 + 1.0 kg a.i./ha followed by supplementary hoe‐weeding resulted in significant weed reduction and the highest okra fruit yield. Metolachlor plus terbutryne and pendimethalin plus prometryne, each at 2.0 + 1.0 kg a.i./ha. followed by supplementary hoe‐weeding also reduced weed infestation significantly and resulted in fruit yield comparable to that of the best herbicide treatment. In 1985 only metolachlor plus prometryne at 2.0 + 1·lb0 kg a.i./ha followed by supplementary hoe‐weeding gave comparable okra fruit yield to the hoe‐weeded control. Compared with pre‐emergence application of herbicides, directed post‐emergence herbicide treatments resulted in significant crop growth depression and unacceptably low okra fruit yields. Losses in fruit yields resulting from uncontrolled weed growth were 99.1% and 100% compared with the hoe‐weeded controls in 1984 and 1985, respectively.

ISSN:0143-6147    

DOI:10.1080/09670879109371544

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0143-6147    

DOI:10.1080/09670879109371546

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor