Abstract

ARIAS RIVAS, Berto; YANEZ, Víctor; CARRIZALES, Luis  and  SANCHEZ, María. Hongos asociados a la caida prematura de frutos en LIMA PERSA (Citrus latifolia Tan.) y  evaluación de su control quimico. Bioagro [online]. 2006, vol.18, n.1, pp.031-039. ISSN 1316-3361.

Tahiti lime is an important crop with high economic potential in Monagas State, Venezuela. The incidence of diseases negatively affects crop yields, causing among other symptoms, postbloom fruit drop. In 2003 a trial was conducted in a commercial citrus orchard and four plant lots were selected in different periods of the year. In each lot four preblooming branches were enclosed in perforated bags on each of eight randomly selected plants. Weekly, the number of flowers and fruits were counted during four consecutive weeks until the fruit reached persistent set. In 2004 the trial was repeated using one branch on each of ten selected trees. Samples of dropped flowers and fruits collected from the enclosing bags were analyzed for isolation of microorganisms, and the percentage of fruit set and fruit drop was determined. An in vitro study was also conducted to determine the efficiency of the fungicides Captan, Benlate, Funcloraz and Curacarb to control the daily radial growth of the main fungus detected. From flowers and fruits affected, two strains of Colletotrichum gloesporioides and one of Rhizopus sp. were isolated, the latter being considered non pathogenic. In 2003 the average of isolation of C. gloesporioides reached approximated values of 40, 50, and 70 % in June, July, and August, respectively; on the other hand, Rhizopus sp. reached maximum values higher than 80 % in the same periods. In 2004 C. gloesporioides was consistently isolated, particularly in the month of July. It is concluded that C. gloesporioides is established in the orchard and is an important factor related to the postbloom fruit drop. The fungicides Funcloraz, Curacarb, and Benlate showed the best in vitro control of C. gloesporioides, while Captan showed low effectiveness.

Keywords : Citrus; Colletotrichum gloesporioides; fungicides.