16. Effect of various fertilizers and rates on insect pest/pearl millet relationship in Senegal.
Trop. Agric. (Trinidad), 69, 2, 1992, pp. 149-152
The work described in this paper was done in Senegal to study the relationship between infestation of stalk borer and spike worm and fertilizer application in traditional and improved pearl millet cultivars.
At present, economical and practical control measures are not available.
Studies on the effectiveness and uses of cultural practices, resistant cultivars and natural enemies had been initiated. Among agronomic practices, application of chemical fertilizer is often used on high-yielding cultivars.
Experiments were conducted on a sandy-loam soil in a randomized block design with four replicates.
Application of complete fertilizer at 50-300 kg ha-1 to two pearl millet cultivars, Souna and IBV-8001, or urea at 50-200 kg ha-1 to cv. Souna, resulted in significantly increased levels of stalk infestation and larval abundance of the stalk borer, but superphosphate when applied at 50-200 kg ha-1 reduced stalk infestation. Urea applications reduced spike infestation caused by the spike worm, and larval numbers were lower in plots receiving urea or superphosphate than in non-fertilized plots.
Stalk borer incidence was greatest in plots receiving nitrogenous or complete fertilizer which may have caused the stalks to be more liable to attack.
Urea fertilization resulted in less spike damage and lower abundance of H. albipunctella larvae and superphosphate reduced only larval densities.
In Senegal, the pearl millet crop is systematically rotated with groundnut in some regions and nitrogenous fertilizer is generally not applied to the next crop after the legume. Application of complete or nitrogenous fertilizer may be avoided in southern regions where stalk borer attack is often severe, whereas these fertilizers would be advantageous in central and northern Senegal because spike worm is an economically important pest. At present, fertilizers are supplied by Government at subsidized prices or free of cost to farmers. The cost should be an important consideration in forthcoming recommendations because pearl millet is a subsistence crop in the Sahel. Thus, the influence of fertilizer application on insect abundance and plant damage should be considered in pest management strategies, particularly in improved/introduced high-yielding cultivars which are being tested in multilocational trials prior to their release to growers.
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Asia, India, study, survey, intercropping, agroforestry, oil palm, insect pests
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