Basal stem rot (BSR), caused by the fungus Ganoderma, is the most serious disease of oil palm in Malaysia and Indonesia. Previously, research on basal stem rot was hampered by the failure to artificially infect oil palms with the fungus. Although Ganoderma had been associated with BSR, proof of its pathogenicity to satisfy Koch’s postulate was only achieved in the early 1990s by inoculating oil palm seedling roots or by using rubber wood blocks. A reliable and quick technique was developed for testing the pathogenicity of the fungus by inoculating oil palm germinated seeds.
This fatal disease can lead to losses as much as 80% after repeated planting cycles. Ganoderma produces enzymes that degrade the infected xylem, thus causing serious problems to the distribution of water and other nutrients to the top of the palm. Ganoderma infection is well defined by its lesion in the stem. The cross-section of infected palm stem shows that the lesion appears as a light brown area of rotting tissue with a distinctive, irregularly shaped, darker band at the borders of this area. The infected tissue become as an ashen-grey powdery and if the palm remains standing, the infected trunk rapidly become hollow.
Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. The pathogen that causes Fusarium wilt is Fusarium oxysporum (F. oxysporum). The species is further divided into forma specialis based on host plant.
[source : Wikipedia ]