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Population Densities of Tylenchulus semipenetrans Related to Physicochemical Properties of Soil and Yield of Clementine Mandarin in Spain

March 2008 , Volume 92 , Number  3
Pages  445 - 450

Francisco Javier Sorribas, Departament d'Enginyeria Agroalimentària i Biotecnologia, Universitat Politècnica de Catalunya, Campus Baix Llobregat, Edifici ESAB, Av. Canal Olímpic s/n, 08860 Barcelona, Spain; Soledad Verdejo-Lucas, IRTA, Protecció Vegetal, Crta. De Cabrils km2, 08348, Cabrils, Barcelona, Spain; Joaquín Pastor, IRTA, Estació Experimental de l'Ebre, Apartat de Correus 203, 43870 Amposta, Tarragona, Spain; Cesar Ornat, Departament d'Enginyeria Agroalimentària i Biotecnologia, Universitat Politècnica de Catalunya, Barcelona, Spain; Joan Pons, IRTA, Estació Experimental de l'Ebre, Tarragona, Spain; and Jordi Valero, Departament de Matemàtica Aplicada III, Universitat Politècnica de Catalunya, Barcelona, Spain



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Accepted for publication 23 October 2007.
ABSTRACT

A survey was conducted from April to June 2002 in 62 orchards of clementine mandarin grafted on Troyer or Carrizo citrange rootstock in Catalonia (northeastern Spain) to determine the relationship between physicochemical soil properties and Tylenchulus semipenetrans population densities. Soil was analyzed to determine texture, pH, electric conductivity, organic matter content, N, P, K, Mg, calcium carbonate, and calcium oxide. Also, trials were conducted in 2003 and 2004 in three drip-irrigated orchards of clementine mandarin cv. Clemenules (El Pla and Mariclaire) or cv. Hernandina (Martorella) to determine the relationship between citrus nematode densities and yield of mandarin. T. semipenetrans was detected in 77% of the surveyed orchards. The number of second-stage juveniles + males in soil was related to N and K soil content (3.57953 -- 0.001305 N + 0.00113 K, R2 = 0.1620, P < 0.0157). The relationship between relative yield of clementine mandarin cv. Clemenules and densities of females per gram of root in spring was described by the Seinhorst damage function model (0.035 + 0.965 (0.9995)(Pi -- 287), R2 = 0.4782, P < 0.0001).


Additional keywords:gain threshold, plant-parasitic nematodes

© 2008 The American Phytopathological Society