Dactuliophora mysorensis sp. nov.: A New Species of Mycelia Sterilia Causing Zonate Leaf Spot on Cowpea in India

Cowpea is an important pulse crop extensively grown in arid and semi-arid tropics which is affected by a number of diseases. Fungi belonging to mycelia sterilia are known to cause many diseases on cereals and pulses. During the cowpea field survey in Mysore District of Karnataka (India), Dactuliophora sp. was identified as the major pathogen causing zonate leaf spot (ZLS) disease. The fungal pathogen was isolated from naturally infected cowpea leaves and identified as a member belongs to the genus Dactuliophora, which was previously described by CLA Leakey in the year 1964 on Vigna unguiculata from Africa. However, detailed morphological and cultural examinations of the pathogen revealed striking differences from that of D. tarrii. Based on differences in morphology with D. tarrii, a new species Dactuliophora mysorensis sp. nov. is described herein. The disease incidence as well as disease index was estimated for 3 years (2016–2018). The severity of the disease was high during August–November. High incidence and disease index of ZLS was recorded in Doddamaragowdanahally region. The pathogenicity tests demonstrated similar symptoms of ZLS. The ITS barcoding revealed that the pathogen is closely related to Rhizoctonia bataticola and Macrophomina phaseolina. Further, in vitro evaluation of fungicides was carried out by poisoned food technique. Among the five fungicides examined, only two systemic fungicides (Benomyl and Carbendazim) were effective against D. mysorensis. Thus, the present study recommends Benomyl and Carbendazim for management of ZLS disease caused by D. mysorensis.