SEASONAL POPULATION CHANGES AND MANAGEMENT OF TYLENCHULUS SEMIPENETRANS USING ORGANIC AMENDMENTS AND FENAMIPHOS

Abstract

Seasonal population variations of the citrus nematode, Tylenchulus semipenetrans in association with grapefruit was studied from September 1995 to August 1997 at Tanuf in Al Dhakhliya (Interior) region of Oman. Nematode populations in soil and roots steadily increased from September and reached high levels during January-March, then sharply declined during summer from May to August. Significant negative correlations were observed between maximum air and soil temperatures and nematode populations in soil and roots. The effect of three organic amendments and fenamiphos on the management of T. semipenetrans was tested on sweet lime. There was no reduction in nematode populations due to application of clandosan at 2.5 t/ha, chopped leaves of harmal (Rhazya stricta) at t/ha and fenamiphos at 8kg a.i./ha. Application of sawdust at 20 t/ha reduced populations of T. semipenetrans compared to controls during both seasons.