Orchid diseases and their control in Malaysia
1980
Lim, Tong-Kwee
Fungicides make up about 44% of the total agricultural chemicals cost for ground orchids and 39% for potted orchids. A survey of farms in two largest orchid growing states (Johore and Selangor) revealed that farmers have been using dithiocarbamate and N-trichloromethylthio and related groups of fungicides as panacea for all their orchid disorders. Of the diseases samples diagnosed, the underlying causes of more than 50% were not determined owing to the great assortment in symptoms and paucity of local background information. The bulk of the remaining problems were diagnosed as fungal and viral in nature. Diseases caused by viruses and Phytophthora palmivora were rampant on most of the commercial varieties in both states. Diseases caused by Colletotrichum gloeosporioides, Sclerotium rofsii and other fungi were more commonly encountered in Selangor. Besides, bacterial diseases caused by Erwinia chrysanthemi and fungal spots on blossoms of Dendrobium, Phalaenopsis and Aranda Christine were more frequent on farms in Selangor. Most of the fungal diseases on orchid blossoms caused by species of Colletotrichum, Botrytis, Curvularia and Fusarium represent new records for Malaysia. The incidence of the various diseases are further discussed in relation to the local growing conditions, existing and improved methods of control.
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