Spatial distribution of chili leaf curl disease and its correlation with environmental factors in Southern Irrigated Plain Zone of Pakistan

Chili leaf curl virus (Genus: Begomovirus, Family: Geminiviridae) a whitefly transmitted virus causing chili leaf curl disease (ChiLCD) occurs in Pakistan. Spatial distribution of ChiLCD and its correlation with environmental factors in southern irrigated plain zone of Pakistan was determined. The incidence and severity was recorded based on biological symptoms. There were five repeats for observation at each site; individual repeat comprised ten chili plants. Incidence of the disease was calculated by using mathematical equation, 0-5 rating scale was used to record the disease severity. Metrological data was collected from nearby regional agro metrological stations. There was significant variation among the disease incidence recorded at different sites of Hyderabad (df= 9, F= 13.5, P= 0.0000), Tando Allahyar (df= 9, F= 1.79, P= 0.1037), Mirpur Khas (df= 6, F= 1.74, P= 0.1555), Jamshoro (df= 5, F= 3.81, P= 0.0138), Larkana (df= 8, F= 9.99, P= 0.0000) and Dadu (df=9, F=3.93, 0.0015). Severity of the disease was ranging between 1 to 2-score in the surveyed areas. The minimum and maximum temperature were significantly related with the disease incidence (r2= 0.7229, P= 0.0458 and r2= 0.8073, P= 0.0218, respectively) but there was non-significant relation with severity of the disease. Incidence of the disease was negatively correlated with relative humidity (r2= -0.8073, P= 0.0218). There was non-significant negative relationship of the disease severity with relative humidity and rainfall (r2= -0.5774, P= 0.1511, r2= -0.3515, P= 0.3894, respectively). Rainfall was also negatively non-significantly correlated with the disease incidence.