Current Status of Citrus Tristeza Virus in Major Citrus Growing Areas of Sargodha, Pakistan.

Tristeza disease is caused by citrus tristeza virus (CTV) expresses salient symptoms like stem pitting, yellowing of leaves, stunted growth of large, small lateral branches and twigs. The study was carried out to quantify the spatial and temporal distribution of CTV disease in major citrus growing areas of Sargodha district (Sargodha, Kot Momin, and Bhalwal). The samples from the declined orchards were collected based on symptomology and confirmed through ELISA. CTV was detected in 3 varieties viz., Kinnow (Citrus reticulate), Mosambi (Citrus sinensis) and Feutrell’s early (Citrus reticulate cv feutrell’s early). The maximum disease incidence was recorded in Mosambi (90%), followed by Feutral’s early (74%) and Kinnow (57%). Mosambi was the most susceptible within the range of OD values (0.82-2.35) followed by Feutrell’s early (0.45-0.64) and Kinnow (0.25-0.56). The disease severity was recorded only on Mosambi as it was more affected than Feutral’s early and Kinnow. The rating scale to observe the severity of tristeza disease was based on percentage of pits in the 1 sq. inch piece of bark at bud union of infected tree. This rating scale has been developed for the first time to record the tristeza disease severity. The maximum disease severity was recorded in Kot Momin (62%) followed by Bhalwal (56%) and Sargodha (50%). The study concluded that CTV is one of the most promising factors playing role in the citrus decline. [ABSTRACT FROM AUTHOR]