Preliminary field test of lyophilised contagious caprine pleuropneumonia vaccine

Fifty goats were immunised in the field against contagious caprine pleuropneumonia (CCPP) using a single dose (0.15 mg) of lyophilised, saponin killed Mycoplasma strain F38. Two months after vaccination, these goats together with 50 unimmunised control goats were challenged by contact with goats experimentally infected with CCPP. Twelve vaccinates and 14 controls died of diarrhoea due to salmonella infection during the first two weeks after challenge. The remaining immunised goats (38) with the exception of two goats which had elevated temperatures were protected from CCPP. Of the remaining 36 control goats, 30 contracted CCPP at a mean of 39 (+/- 14.3 SD) days after challenge and 27 of them died. These results show that the lyophilised killed F38 vaccine conferred 100 per cent protection against mortality and 95 per cent protection against clinical disease caused by Mycoplasma species strain F38.     

Effect of Social Capital on Performance of Smallholder Farmer Organizations in Western Kenya

Development literature has recently promoted the use of producer organizations in linking farmers to better-paying commodity markets. However, empirical studies find mixed performance of such organizations. This study examines the producer organizations＇ internal factors that may explain the differences in the performance of producer organizations. The study specifically analyzes the role of social capital, within a producer organization, on the performance of such organization using quantitative techniques. The level of commercialization is used as proxy of organization＇s performance. The study finds that social capital positively affects the performance of producer organizations. These findings imply that development strategies that target the promotion commercialization of smallholder agriculture through producer organizations should pay attention to the internal factors within such organizations.     

Eradication of potato virus Y and S from potato by chemotherapy of cultured axillary bud tips

Ribavirin (virazole) treatment of cultured axillary bud tips (3-4 mm) was tested as a method of eradicating potato virus Y (PVY) and potato virus S (PVS) from two potato cultivars, Norchip and Desiree. Ribavirin treatment was phytotoxic at all concentrations tested, but cultivars treated at 5 mg/1 were visually similar to the nontreated control cultures after 20 weeks. The buds treated with ribavirin at 20 mg/1 had a survival rate of only 30–40%. Virus assays indicated that 2,74,82, and 89% of the plants were free of PVY, and 1, 71, 83 and 90% were free of PVS, 20 weeks following treatment with 0, 5, 10, and 20 mg/1, respectively. Virus assays indicated that 2, 74, 82, 89% of the plants were free of PVY, and 1, 71, 83 and 90% were free of PVS, 20 weeks following treatment with 0, 5, 10, and 20 mg/1 ribavirin treatment respectively for cultivar Norchip. Desiree cultivar assayed 2, 69, 80 and 86% free of PVY and 2, 74, 85 and 93% free of PVS, 20 weeks following treatment with 0, 5, 10, and 20 mg/1 ribavirin treatment respectively.     

Multipurpose leguminous trees and shrubs for agroforestry

These are various ways in which farmers deliberately incorporate trees and shrubs on farm production fields. Many of the species so incorporated are legumes. The role of such woody perennials in agroforestry systems can be productive and/or protective. Legumes offer by far the maximum range of choice of woody species for agroforestry in terms of their economic uses as well as ecological adaptibility. In addition to the several leguminous woody species that are well known in agroforestry, there are many more whose potentials have not yet been fully understood. An evaluation is presented of the agroforestry potentials of a few leguminous species from the point of view of their growth characteristics, ecological adaptability, combining ability with other species and uses/functions. The science of agroforestry is still in its infancy. There exists no research data on the various management aspects of these potentially promising group of plants. ICRAF, in its capacity as an international research council, has assembled several multipurpose leguminous trees and shrubs of agroforestry potential at the Council's recently-established Field Station in Machakos, Kenya, primarily for demonstration and training purposes. Initial results from these trials are presented in the paper.Adapted from a paper presented at the International Symposium on Nitrogen Fixing trees in the Tropics, 19–24 September, 1983 Rio-de-Janeiro, Brazil.