Maize earworm attack as influenced by varying maize spatial arrangement and population in maize-soybean mixture

Abstract

The effect of spatial arrangement and maize population in maize-soybean mixture on maize earworm attack was studied at Nsukka, Nigeria for four years, 1997-2000. The treatment consisted of three maize population densities of 40,000, 60,000 and 80,000 plants ha-1, and three row-arrangements of maize: soybean mixtures of 1:1. 1:2 and 1:3 in all possible combinations. There were also three sole crop populations of maize and one of soybean. This resulted in 13 treatments which were laid out in field plots in a Randomized Complete Block Design (RCBD) with three replications. The result showed that intercropping maize and soybean did not reduce maize earworm infestation. Maize population at 80,000 plants ha-1 significantly reduced the infestation by maize earworm and maize cob sizes compared to populations at 40,000 or 60,000 plants ha-1 (P = 0.05). Highly significant positive correlations were established in all the years between earworm population and maize ear sizes. The correlation between damage incidence and severity were inconsistent Land equivalent ratios (LER) at 40,000 and 60,000 maize ha-1 were significantly higher than LER at 80,000 maize ha-1. The differences among the spatial arrangement and its interaction with maize population did not attain any level of statistical significance.
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Keywords: Maize earworm, Spatial arrangement, Maize population, Maize-Soybean mixture

Agro-Science Vol. 4 (1) 2005: pp. 60-65