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Sudan Journal of Agricultural Research

An attempt to evaluate economic decision making in pest management by farmers

S. Akoi Binyason, Z.T. Dabrowski and Immam El-Khidir.

Abstract.

This study was initiated to evaluate economic decision making by farmers as a pest management strategy, by comparing the standard pest sampling technique for determining economic threshold (ET) with that of farmers without standard procedures. Add to this, to train farmers the technique of using photography for detecting leaf-colour changes of eggplant Solanum melongena (L) due to damage by jassid, Jacobiasca lybica (de Berg.) and to match such knowledge with jassid numbers in quest to derive their ET at which to spray eggplant. The results showed that the ET for the standard pest sampling method was 54.3 jassids/100 leaves with a yield of 55.5kg/plot as a control, compared to 166.8 jassids/100 leaves, with yields ranging from 5.0-18.8kg/plot in farmers’ fields. General ET for the experiment with the control was 144.3 Jassid/100 leaves. The variability of yields among farmers was probably reflecting the differences in decision- making. Nevertheless, the differences were proportionally related to the different jassid populations. Reduction on leaf damage was 12.1% and that on flowers was 11.0% at the lowest ET (0- 1) jassids/leaf in the cage experiment and increased to 64.3% and 77.6% at the highest density, 10 jassids/leaf, respectively. On the other hand, the ET favored by interviewed farmers using the photography technique was 2-3 jassids/leaf, representing 200-300 jassids/100 leaves, under field conditions. No leaf colour changes were observed in plants with ‘0’ jassid/leaf. Farmers should spray eggplant when symptoms are still difficult to recognize i.e. (ETL = between 0-1 jassids/leaf) to prevent the jassid population from reaching the economic injury level (EIL).
 

Sudan Journal of Agricultural Research Vol. 9 (2007) PP. 121-127