Impact of Nitrogen fertilizers on the sustainability of Alternaria porri (Ellis) in the field of onion.

Alternaria porri is the most common pathogen associated with the leaf of onion causing the disease purple blotch (Dongre, M.A and Borse, K.N. 2015). It affects the green mature leaves of onion (Suheri and Price, 2001). The spores which are present in the soil as well as in the air get germinate on leaves and produce minute water-soaked spots, which later turn to brown and dark brown.Onion crops require high nitrogenous fertilizers (Gebretsadik, K., Dechassa, N. 2018). At least 1 to 1.5 kg of Nitrogenous fertilizer per 100 feet row of onion crop. The ammonium sulfate or ammonium nitrate are the main fertilizers use to compensate the N2 level for the onion crop (Andreas et al.2003). This leads to reducing the pH of the soil and increases the acidity of the soil (www.blinc.com/role-nitrogen-fertilizer-soil-ph).