Management of purple blotch disease in onion (<i>Allium cepa L.</i>) using organic amendments

Abstract

The management of purple blotch disease in onion by soil amendments was investigated in a screen house experiment. Soil application of poultry droppings, cattle dung, rice husk and neem leaves at 100, 150 and 200g/kg soil reduced purple blotch severity significantly. Soil amendments with poultry droppings was most effective; reducing the severity from 4.8 ± 0.2 in the unamended soil (control) to 1.4 ± in poultry dropping amended soil at 200h/kg soil. The soil population of Alternaria porri was reduced from 36 ± 1.7 x 105g^-1; also at 200g/kg poultry dropping amendment. The amended soils developed microflora including Trichoderma harzianum, Fusarium culmorum, Penicillium cyclopium, Bacillus cereus and B subtilis. Highest populations of the fungi were contained in poultry dropping amended soil. Bacillus cereus and B. subtilis were also higher in poultry dropping amended soil. The suppression of purple blotch disease of onion .examined in this study was related directly to microbial properties of the amendments.