Management of seed borne inoculum of Xanthomonas cucurbiate causing bacterial leaf spot of pumpkin and bottle gourd

Abstract

Bacterial leal spot is a common and destructive disease of cucurbits. Recent research revealed the seed borne nature of Xanthomonas cucurbitae . In this study, seeds wrapped in muslin cloth were dipped in various treatments involving hot water and chemicals. Hot water treatment of seeds at 55°C for both pumpkin and bottle gourd isolates resulted in minimum (28.73 and 23.33%, respectively) seedling infection. In vitro evaluation of fungicides and antibiotic (streptocycline) by using paper disc method revealed that Bordeaux mixture and copper oxychloride to be most effective against pumpkin and bottle gourd, respectively. Under chemical seed dip treatments, the minimum number of infected seedlings were recorded with streptocycline (37.64%) and copper oxychloride (40.80%) for pumpkin and bottlegourd, respectively. For both the isolates, maximum seed germination was recorded in seeds treated for 720 minutes (98.20 and 98.60%, respectively). A combination of streptocycline and copper oxychloride as seed treatment for three hours gave best results for both the isolates (16.33% and 15.67%, respectively). Under pot house conditions, combining streptocycline (100 ppm) and copper oxychloride (3000 ppm) as a seed dip treatment for three hours was found to be the most effective. The recorded minimum disease severity was 18.00 and 22.00%, respectively.