Biological Control of Carrot Black Rot

Diseased carrot seeds were treated with selected micro-organisms isolated from soils, carrot seeds and tap roots. The effects of those antagonists on the control of Alternaria radicina were evaluated by growing-on tests on water agar, filter paper, vermiculite and in a potting medium (BVB no. 4). The germination percentage, emergence percentage and the disease severity of those carrot seeds treated with Burkholderia (Pseudomonas) cepacia no.229 were significantly (P=0.05) differed from the non-treated seeds and the seed treated with other antagonists. The effects of B. cepacia no.229 in promoting seed emergence and controlling disease were as good as those seeds treated with iprodione (100 p.p.m.). Black rot lesions on carrot tap roots were significantly reduced (P=0.05) in size when roots were treated with B. cepacia no 229 or Bacillus amyloliquefaciens no. 224 compared to the nontreated roots. Also, B. cepacia no. 229 significantly (P=0.05) reduced black rot on the foliage of carrot compared to check.