Influence of Aldicarb and Fenamiphos on Tylenchulus semipenetrans Population Densities and Orange Yield


  • N. Greco
  • M. Basile
  • T. D'Addabbo
  • A. Brandonisio


The effect of aldicarb and fenamiphos on Tylenchulus semipenetrans population densities and on orange yield was investigated during a 3-year (1986-88) field trial in Italy. Rates were 10 and 20 kg a.i./ha as an early spring single application, 5 kg a.i./ha in spring and 5 kg after flowering, and 5 kg a.i. in spring followed by 2.5 kg/ha after flowering and 2.5 kg/ha in early autumn. Rates and times of application of the two nematicides did not affect numbers of females of T. semipenetrans on the roots but suppressed (P = 0.05) egg, male, and second-stage juvenile population densities from October 1986 to 1988. Yield of fruit was not affected by any treatment during 1986-87. Yield was increased (P = 0.05) in 1988 by i) a single application of 20 kg a.i./ha aldicarb, ii) 10 kg a.i./ha fenamiphos, and iii) an application of 5 kg a.i. aldicarb/ha in spring, followed by two more applications of 2.5 kg/ha each in June and September. Fruit size was not affected by the nematicide treatments. Concentrations of fenamiphos and its metabolites, in rind and pulp, were below 0.02 ppm. Key words: aldicarb, citrus nematode, Citrus sinensis, control, fenamiphos, nematicide, nematode, orange, residue, Tylenchulus semipenetrans.