Efficacy of Pongamia pinnata seed oil as a fumigant in reducing surface infestation by sapstain and mould fungi in bamboo

Abstract

Sap stain fungi causes discolouration in bamboo, which reduces the aesthetic value of bambooproducts and renders them unfit for any specific use in which appearance is a crucial factor in determining its value besides its durability. The efficacy of Pongamia pinnata seed oil (PSO) as a fumigant was tested against sapstain (Alternaria alternata) and mould (Aspergillus niger) fungi with a petri plate bioassay, observing growth inhibition by different concentrations of PSO. Growth inhibition ( %) was recorded as 65.8 % for 0.3 % PSO and 88.5 % for 0.5 % PSO.A 1.0 % PSO concentration showed almost complete (i.e. 98.8 %) growth inhibition in A. alternata. Growth inhibition of A. niger was 62.3 % for 0.3 % PSO, 92.6 % for 0.5 % PSO and 98.7 % for 1 % PSO compared to control samples. Surface coverage test by sapstain and mould fungi on 3 different bamboo species B tulda, Bambusa balcooa and Dendrocalamus strictus was also studied. Fumigation with PSO was effective in inhibiting the growth of sap stain and mould fungi in reducing surface infestation on all 3 bamboo species. Our results show that growth inhibition increased gradually with increasing PSO concentration and that complete inhibition in the growth of A. alternata and A. niger was observed in all bamboo species fumigated with a 15 % concentration of PSO.