POSTHARVEST CONTROL OF FRUIT ROT OF MANGOSTEEN BY PLANT EXTRACTS FROM ZINGIBERACEAE FAMILY

Fungi causing fruit rot of mangosteen were isolated from the calyx, fruit peel, and petals of harvested fruits. Isolates were identified as Colletotrichum gloeosporioides, Lasiodiplodia theobromae, Pestalotiopsis sp., and Phomopsis sp. Antifungal bioassays of rhizome crude extracts of the Zingiberaceae family, Alpinia galanga, Zingiber montanum, Curcuma longa, and C. zedoaria were tested against the postharvest pathogens. The antifungal activity of the lipophillic phase of the crude extracts was determined by a micro dilution technique. A. galangal extracts were found to be the most effective, with a minimum inhibitory concentration (MIC) of 78 µg/ml against C. gloeosporioides. Fraction sample B from column chromatography showed spore inhibition at a MIC of 1,250 µg/ml. A 10,000 ppm extract in 5% methanol was most effective in controlling fruit rot caused by Phomopsis sp., and wrapping fruits with soaked extract paper decreased disease incidence caused by Pestalotiopsis sp.