EFFICACY OF CHEMICALS FOR CONTROLLING COLONY SPREAD BY RHIZOPUS SPECIES

Of various chemicals tested, dichloran was found to be most effective for restricting the rates of colony spread by three Rhizopus species a t the lowest concentration (25 mg/L or less) on potato dextrose agar a nd Czapek Dox agar. Higher concentrations of methyl red (50 mg/L), ros e bengal (50 mg/L), Triton X-100 (100 mg/L), bromocresol green (500 mg /L), sodium deoxychlorate (500 mg/L) and oxgall (3000 mg/L) were requi red to equally reduce colony spreading. Tween 80 (5000 mg/L) and metha nol (50 000 mg/L) did not reduce the colony diameters of the molds. R. oryzae grew faster and was more tolerant to chemicals than R. oligosp orus and R. stolonifer.