Control of Tylenchulus semipenetrans on Citrus with Fenamiphos and Oxamyl. R. M. Davis, Associate Professor, Texas A&I University Citrus Center, Weslaco 78596. H. S. Wilhite, Research Assistant, Texas A&I University Citrus Center, Weslaco 78596. Plant Dis. 69:974-976. Accepted for publication 12 April 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-974.

In a 2-yr field study, fenamiphos and oxamyl applied to citrus trees by drip irrigation significantly reduced numbers of juvenile citrus nematodes (Tylenchulus semipenetrans) but did not increase fruit yield or size. Fenamiphos applied directly to the soil in flood-irrigated plots was more effective in reducing numbers of the nematode than was fenamiphos or oxamyl applied by drip irrigation, but again, neither yield nor quality of fruit was improved. Mortality of juveniles in the soil may not be a good indicator of the benefits of a nematicide on citrus since yields were not improved and neither nematicide reduced the numbers of mature females feeding on roots.