OCCURRENCE AND DISTRIBUTION OF THE CITRUS NEMATODE (TYLENCHULUS SEMIPENETRANS) IN JORDAN

Abstract

One-hundred and sixty-two composite soil samples were taken during October 1990 and March 1991 from citrus groves in the Northern Jordan Valley, Central Jordan Valley, Southern Jordan Valley, Southern Ghors, Jerash and Wadi Shueib. Field sampling revealed that the citrus nematode (Tylenchulus semipenetrans) was widely distributed in citrus groves in Jordan. Slow decline disease of citrus, caused by the citrus nematode, appeared to be of large magnitude in the older plantations in the Northern Jordan Valley. Second stage juvenile population densities at Deir Alla Station were found to increase in the autumn and spring seasons, but fell down the minimum level in mid summer. Nematode numbers were high in sandy-loam soils (30.8% - 69.8% sand, 11.2% - 33.2% clay and 19.0% - 36.0% silt). Moreover, soils containing lower organic matter (0.77% - 1.43%), sustained higher numbers of the citrus nematode.