Population responses of the citrus red mite and citrus thrips to 'navel' orange cultural practices.
1989
Hare J.D. | Morse J.G. | Menge J.L. | Pehrson J.E. | Coggins C.W. Jr. | Embleton T.W. | Jarrell W.M. | Meyer J.L.
Field-grown orange (Citrus sinensis (L.) Osbeck) trees were subjected to all combinations of three levels of irrigation, three levels of fertilization, two levels of fungicide-nematicide applications, and two levels of growth regulator treatments during 1985-1987. Densities of the citrus red mite, Panonychus citri (McGregor), and densities and fruit scarring caused by the citrus thrips, Scirtothrips citri (Moulton), were monitored in 1986 and 1987 to determine how variation in commercial orange grove management practices might alter the suitability of trees for use by both pest species. Fertilization was the only factor exerting a consistent, significant effect on thrips scarring and mite density. Citrus thrips scarring was highest on the most heavily fertilized trees, whereas mite densities were highest on the least fertilized trees. Although fertilization significantly altered concentrations of several individual amino acids, soluble protein, and total nitrogen content, variation in densities of neither arthropod was strongly related to variation in concentrations of any measured plant compounds. Differences in densities and scarring among treatments were low relative to conventional treatment thresholds, and variation in grove management practices, within practical limits, probably play only a minor role in promoting outbreaks of either of these two citrus pests.
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