Chitosan coating for inhibition of Sclerotinia rot of carrots

In in vitro tests, chitosan at 1, 2, and 4% (w/v) significantly reduced the growth of Sclerotinia sclerotiorum on potato dextrose agar plates. The effect of chitosan coating on sclerotinia rot of carrots (Daucus carota L.) held at 22 degrees C was also investigated. Carrot roots were coated with chitosan solutions (2 or 4%) and inoculated with mycelial plugs of S. sclerotiorum culture. After 5 days of storage, chitosan at both rates reduced significantly the incidence of rot (from 88 to c. 28%) and also the lesion size (from 26 to c. 12 mm) of the rot on roots. Microscope studies revealed that fungal mycelium exposed to chitosan appeared to be deformed and dead, whereas untreated mycelium was normal in appearance.