OCCURENCE OF MAJOR DISEASES ASSOCIATED WITH SELECTED GARLIC VARIETIES AND MANAGEMENT OF PURPLE BLOTCH DISEASE CAUSED BY Alternaria porri

Abstract

Two experiments were conducted at the central farm of Sher-e-Bangla Agricultural University and in the central Laboratory, Department of Plant Pathology, Sher-eBangla

Agricultural University, Dhaka, Bangladesh during the Rabi season from November 2018 to March 2020 in order to study the field evaluation of major diseases of selected garlic varieties and integrated management of purple blotch caused by Alternaria porri. The 1 st experiment was laid out in a Randomized Complete Block Design (RCBD) with 3 replications and eight varieties were used. For the 2

experiment, nine treatments viz. one bio-agent Trichoderma harzianum (T ), five botanical plants extracts viz. Lantana camara (T iii

2 ), Spilanthes paniculata (T ), Ocimum sanctum (T 4 ), Raphanas raphanistrum (T 5 ) and Azadirachta indica (T ) and two fungicides Mancozeb 80% WP (T 7 ) and Sulcox 50% WP (T ) and, without treatment marked as control (T ) were used in management of purple blotch of garlic. During field evaluation, BARI Rashun-3 variety showed the highest disease incidence and severity of purple blotch disease (40.00 and 92.00%) and white rot disease (33.33 and 89.33%), respectively. In case of viral diseases, Local Indian variety scored the highest disease incidence and severity of Iris yellow spot virus (39.44 and 88.00%). BARI Rashun-2 showed the highest incidence (20.00%) and BARI Rashun-3 noted with highest severity (77.33%) of Yellow dwarf virus. Negative correlation were found between %disease severity and yield (t/ha). Mean performance of yield parameter varied significantly. In case of management, all botanicals and Trichoderma harzianum were found significantly effective in reducing purple blotch disease incidence and severity in compare to control. The results revealed that Lantana camara (T 2 9 ) was found most effective for minimizing the disease incidence (26.67, 26.67 and 33.33%) at all 30, 45 and 60 DAS. However, maximum disease incidence was recorded in control T (86.67, 96.67 and 100.00%). Furthermore, Lantana camara (T 2 9 ) was found most effective in reducing disease severity at 30 DAS (11.00%) whereas, at 45 DAS and 60 DAS (18.67 and 19.33%) T

(Trichoderma harzianum) was found most effective.