Variability and Integrated Management of Purple Blotch of Garlic Allium sativum L Caused by Alternaria porri Ellis Ciferri

Abstract

Garlic (Allium sativum L.) is the second most widely cultivated bulb crop after newlineonion and used as a spice or condiment throughout India. Purple blotch caused by newlineAlternaria porri (Ellis) Cifferi is a serious disease affecting both foliage and bulb newlinedevelopment. The present investigation involving roving survey, laboratory studies on newlinepathogenic variability with respect to cultural, morphological and molecular characters, newlineevaluation of fungicides, bioagents, indigenous technology knowledge (ITK s) and newlinecommercially available botanicals against pathogen were undertaken at Department of Plant newlinePathology, College of Agriculture, Dharwad while, field studies on integrated management newlineand screening of genotypes at AINRPOG (All India Network Research Project on Onion newlineand Garlic), Main Agricultural Research Station, UAS, Dharwad during 2018-2021. newlineRoving survey conducted in Bagalkot, Belagavi, Dharwad, Gadag, Haveri and newlineVijayapura districts indicated higher severity of purple blotch in Dharwad district (22.78 newlineand 24.81% during Kharif 2019 and 2020; 27.80 and 26.46% during Rabi 2019 and 2020 newlinerespectively) whereas, minimum per cent disease severity was noticed in Gadag district newline(14.95 and 17.43% during Kharif 2019 and 2020; 17.40 and 20.18% during Rabi 2019 and newline2020, respectively). newlineFifteen isolates of A. porri showed variability with respect to morphological, newlinecultural and molecular characters. There were cultural variations in the colony colour from newlinegrey to brown, margin from irregular to regular. Mycelial growth observed to be flat to newlineraised, texture was either smooth or coarse and even there was variation in growth rate. newlineMorphological variations in the conidial size, beak size and number of septa in conidia and newlinesporulation pattern were also observed within the isolates. Molecular variability among the newlineisolates of Alternaria porri was studied by using two pathogen specific primers (Alt a1 and newlineATPase). Based on phylogenetic analysis, the isolate UASAp6 was closely related with newlineChaAp5 and RamAp9 isolates whereas, the isolate KonAp