Reduction of Bacterial Blight Infestation of Cotton Seeds by Treatment with Sodium Hypochlorite

The efficacy of sodium hypochlorite (NaOCl) for restraining cotton seed infestation by Xanthomonas campestris pv. malvacearum was studied. Seeds of three cotton cultivars were artificially inoculated by soaking in suspensions (ca. 5.10 ⁸ CFU/ml) of different strains of Xcm. Twelve h after soaking (at 30°C) various dilutions of NaOCl were added to the soaking suspensions and incubated for another 12 h. The infestation rate of cotyledons and effect on germination were determined 14 and 21 days after treatment under the standardized conditions of a growth chamber (12 h 20,000 Lux at plant height, 30/20 °C day/night, ca. 100 % relative humidity). Cbncentrations below 0.15 % of active chlorine in the soaking-water had no marked effect on reduction of the disease. Goncentrations between 0.45 % to 0.60 % appeared to be most effective without reducing germination rate. Seed germination was affected, however, by concentration of active chlorine above 0.6 %. Seed quality during sodium hypochlorite treatment obviously influenced the effectivity of this measure.