Effects of granular nematicides on Valencia orange trees infested with Tylenchulus semipenetrans

Abstract

Three granular nematicides were applied at six-seven week intervals to soil around Valencia orange trees infested with the citrus nematode, Tylenchulus semipenetrans. Fenamiphos [two and three applications of 10 kg active ingredient (a.i.)/ha] and aldicarb (three applications of 8 kg a.i./ha) temporarily reduced populations of T. semipenetrans in roots, but fruit yields did not increase in the two subsequent harvests. 1,2-dibromo-3-chloropropane (D.B.C.P.) (two applications of 40 kg a.i./ha) had no effect on either nematode populations or yield. The nematicides did not affect the percentage of California red scale parasitized by biological control agents. Aldicarb residues were found in orange pulp, juice and rind eight months after application, but low residues of D.B.C.P. were found only in rind, and no fenamiphos residues were detected.