Division Sudan Black test:F1

Flood each slide with 0,3 % Sudan Black B solution in 70 % ethanol and incubate for 10 minutes at ambient temperature.

Drain off the staining solution and wash briefly in tap water, removing excess water with tissue paper.

Dip the slides briefly in xylol and blot dry on tissue paper. Caution: Xylol is harmful, take necessary safety precautions and work in a fume cupboard .

Flood the slides with 0,5 % (w/v) aqueous safranin and leave for 10 seconds at ambient temperature. Caution: Safranin is harmful, take necessary safety precautions and work in a fume cupboard .

Wash in gently running tap water, blot dry on tissue paper and apply a coverslip.

Examine stained smears with a light microscope using transmitted light under oil immersion at a magnification of 1 000 using an oil-immersion objective.

Observe for blue-black staining of PHB granules in cells of R. solanacearum with pink-stained cell walls.