Malaysian Journal of Microbiology, Vol 1 (2) 2005, pp.46-52 46 Morphological Characteristics and Somatic Incompatibility of Ganoderma from Infected Oil Palm from Three Inland Estates Latiffah, Z.* and Ho, Y.W. Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor Email: Lfah@usm.my _______________________________________________________________________________________________ ABSTRACT The morphological characteristics of Ganoderma basidiomata from infected oil palms from three inland estates showed some variations, but all fall within the description of G. boninense, based on Steyaert s classification system (1967, 1975). Pairings of G. boninense isolates from the same estate showed that there was somatic incompatibility among the isolates which indicated that the isolates were distinct individuals and not clones of single genotypes. Keywords: Ganoderma, oil palm, somatic incompatibility _______________________________________________________________________________________________ INTRODUCTION Basal stem rot caused by Ganoderma is the most serious disease of oil palm in Malaysia. The disease was first reported by Thompson (1931) and was initially considered a disease of older palms. However, with successive planting of oil palm in the same field and planting in areas that previously supported coconut, the disease began to appear in much younger palms of 10 to 15 years old (Turner, 1981). Now, Ganoderma has been found to infect oil palms of 1 to 2 years old, particularly in replanted areas (Singh, 1990). The highest disease incidence is in coastal areas (Navaratnam, 1964; Turner, 1981; Khairudin, 1990). This is attributed to planting in previous coconut stands (Turner, 1981) and the nature of the soil and its water table (Turner, 1981; Singh, 1990; Khaurudin, 1990). In the past ten years, the disease has also been detected in inland areas (Singh, 1990; Khairudin, 1990; Benjamin and Chee, 1995). The disease usually occurs in the valleys and occasionally on the hill slopes (Singh, 1991). Disease incidence between 2% to 5% had been reported in two inland areas i.e. Gomali Estate, Johor, and Regent Estate, Malacca (Khairudin, 1990). Other disease incidences in inland areas were in Batu Anam, North Johor, where 29% to 50% of 27-year-old oil palms planted in Munchong soil series were affected by the disease and in Gemencheh, Negeri Sembilan, where 11.7% of 27-year-old oil palms planted on lateritic soil were also infected by the disease (Benjamin and Chee, 1995). Pathogenicity test of G. boninense on oil palm seedlings grown on inland and coastal soil types showed mortality rate of 60% to 70% which indicated that oil palm seedlings grown on inland soils are as easily infected by the disease as those grown on coastal soils (Ho and Khairudin, 1995). Present address: School of Biological Sciences, Universiti Sains Malaysia, 11800 Minden, Penang. A number of studies have been carried out on species identification of Ganoderma in the coastal areas but there is very limited information on Ganoderma from the inland areas. Thus, the present investigation was conducted to study the morphological characteristics of Ganoderma from three inland estates and to determine the somatic incompatibility of the Ganoderma isolates from the same estate to establish whether they were different genotypes or clones of single genotypes. MATERIALS AND METHODS Morphological Studies A total of 182 Ganoderma basidiomata were collected from living infected oil palms from three inland estates, namely, Bukit Serampang Estate, Tangkak, Johor; Regent Estate, Tampin, Negeri Sembilan and Paya Lang, Segamat, Johor. Most of the infected oil palms showed obvious skirting symptom. Collection of basidiomata was made from the same tree as well as adjacent trees. The morphological characteristics used to study the Ganoderma basidiomata were the same as those described by Steyaert (1967, 1975) and Ho and Nawawi (1986). Isolation of Ganoderma Mycelium Isolation of mycelium was made from the basidiomata. Small pieces of basidiomata (4 mm x 4 mm x 5 mm) were cut and surface sterilised with 5% sodium hypochloride for 3 min, 0.1% HgCl2 for 1 min, and 2% sodium hypochloride for 2 min, blotted dry and plated on malt agar (MA) with streptomycin sulphate in Petri dishes. Visible mycelia grown from the pieces of basidiomata were subcultured onto fresh MA medium in Petri dishes. *Corresponding author