Abundance of the citrus mealybug, Planococcus citri (Risso) on some citrus species, in the Gezira State (Sudan) and the efficacy of the petroleum spray oil D-C Trom(R) Plus in its control
2005
Abdalla, T.E., Agricultural Research Corporation, Wad Medani (Sudan) , Entomology Secddtion, Crop Protection Research Centre | Osman, E.A., Agricultural Research Corporation, Wad Medani (Sudan) , Entomology Secddtion, Crop Protection Research Centre
This study was conducted during 2004 and 2005 seasons, to quantify the abundance of the citrus mealy bug, Planococcus citri (Risso), on sour lime (Citrus aurantifolia) and grapefruit (c. paradisi) trees in the existing orchards of the Gezira State (Sudan), and to determine the efficacy of the petroleum spray oil (PSO) D-C Tron Plus in its control. The results showed that, the pest was widely distributed throughout the State. The infested sour lime trees ranged between 6.2% and 81.4% of the total planted, and grapefruit trees ranged between 25% and 100%. The infestation was higher in the southern compared to northern Gezira. The important factors determining the intensity of P. citri incidence were found to be climatic conditions, diversification of plant species within an orchard, plant spacing, management and age of the trees. The tested doses of the D-C Tron Plus 0.375%, 0.5% and 0.625% were highly effective in controlling the pest and then significantly increased the marketable yield in terms of fruits number and weight per tree as compared with the control. The highest dose, 0.625%, consistently and significantly gave the best results compared with the two lower doses. The study recommended the D-C Tron Plus at 0.625% (v/v) (product / water) for the control of the citrus mealy bug, diversification of plant species in an orchard, spacing of citrus trees at 8 x 8 m, as recommended earlier by ARTC, and adoption of annual pruning, hedging and topping cultural practices, particularly on closely spaced trees
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