THE EFFECT OF SINGLE AND DUAL INFECTIONS OF CITRUS TRISTEZA VIRUS AND CITRUS VEIN ENATION VIRUS ON CITRUS SPECIES

Viral diseases caused by CTV and CVEV induce dwarfing on plants and severe damage and yield loss to the citrus crop. The virus transmitted through infected plant material and by the same vectors, aphid. Problems cited in the field are complex of symptoms of the two diseases that are difficult to distinguish. This study aimed to determine the effect of single and dual infections of CTV and CVEV on Purut (Citrus hystrix) and Lime (Citrus aurantifolia). The research was conducted at the screen house and laboratory of Balitjestro, Batu and University of Brawijaya in October 2014 to April 2015. CTV and CVEV isolates used were from Balitjestro’s collection. Treatments conducted were single inoculation for CTV and CVEV, 3 combinations of CTV and CVEV dual inoculation. Each treatment was carried out both on Purut and Lime. A total of 6 treatments and 5 replications were arranged in a Randomized Complete Design; each replication comprised of two plants. The results showed that the symptoms on Purut appeared faster and more severe than those on Lime. Both single and dual infections of CTV and CVEV affected the incubation period of CTV on vein clearing symptoms, cupping and vein enation. Symptom of vein clearing was found the fastest at dual infections treatment of CTV followed by CVEV. Cupping symptom was seen the fastest in the treatment of dual infections of CVEV followed by CTV, and symptom of vein enation was found only in a single infection of CVEV. The highest disease intensity and infection of vein clearing and cupping were observed on dual infections of CVEV followed by CTV while the highest infections of vein clearing and stem pitting were obtained from simultaneous dual infection of CTV and CVEV. The results of serologic testing by DAS ELISA on three observations (44 days after inoculation (dai), 86 dai, and 142 dai) showed that a dual-infection showed greater absorbance value than single infection treatment did. Plants growths on dual infections treatment were slower than those on single infection.