Symptoms and control of purple blotch disease in Onion

This disease is caused by Alternaria porri, a soil borne fungus.
Symptoms of this disease initially are white brown spots that are purple in the middle which develops on the stems of onion leaves .
Infection of this disease is more when the temperature is 27 to 30 degree centigrade and humidity is high.

Chemical treatment:

Thiophene methyl 70% W/P@ 300 gram/acre or Carbendazim 12% + Mancozeb 63% WP @ 300 gram/acre or hexaconazole 5% SC @ 400 ml/acre or Tebuconazole 10% + Sulfur 65% WG @ 500 gram/acre or chlorothalonil 75% WP @ 400 gram/acre or kasugamycin 5% + copper oxychloride 45% WP @ 300 gram/acre.

Biological treatment:

As a biological treatment, use Pseudomonas fluorescens @ 250 gram/acre or Trichoderma viride @ 500 gram/acre.