3.7.75
SURVEY OF CITRUS DISEASES IN THE ORCHARD OF CARONI (1975) LTD, TRINIDAD

SN JONES1 and B LAUCKNER2

1< /sup>Caroni (1975) Ltd, Research Station, Carapichaima, Trinidad; 2Caribbean Agricultural Research and Development Institute, University of the West Indies, St. Augustine, Trinidad, W.I.

Background and objectives
Caroni (1975) Ltd currently has approximately 700 ha of orange and 315 ha of grapefruit established in Trinidad, W.I. Almost all the citrus is grown on sour orange rootstock and was planted between 1984 and 1991. Tree death and decline are apparent in the orchards.

Materials and methods
During 1995 to 1997 a survey of the orchards was conducted to estimate the level of disease with particular reference to citrus tristeza virus (CTV), foot rot (Phytopthora spp.), and psorosis. Assuming a random distribution of diseased trees in the orchard, trees were randomly selected from each citrus field. Selected trees were visually assessed for psorosis and foot rot. The presence of CTV was determined by direct tissue blot immununoassay [1].

Results and conclusions
The survey revealed high levels of foot rot within the orchard. In the grapefruit plantings, the incidence of foot rot exceeded 50% whereas in the orange plantings the incidence was approximately 25%. CTV incidence was higher in orange than grapefruit.

References
1. Garnsey SM, Petar TA, Cambra M, Henderson CT, 1994. Proceedings Twelfth 1OCV Conference, pp.39-50.