Serious basal stem rot (BSR) was observed in a handful of first generation oil palm fields at Pamol Sabah when due far replanting at 25 years. In the worst affected field, 29 per cent of the stand was infected. The disease re-appeared as early as the sixth year in the replant, rising sharply from the ninth year and reached 30 per cent by the fourteenth year. The disease was scattered and widespread. It developed slightly earlier in underplanted fields than in clear-planted ones but by 14 years after planting there was no difference in incidence. It spread faster where the diseased old stand was windrowed and not removed. Such sanitation was less effective in the new stand, which may require larger excavations. Soil mounding of infected palms did not retard Ganoderma spread. Diseased palms produced 10, 30 and 50 per cent respectively less yield in the year prior to, in that year, and in the year afier disease detection. The decline was due to fewer fruit bunches that also became smaller as the disease progressed. Their fruits also had less oil from more water in the mesocarp. The yields of the immediately neighbouring palms increased by 14 per cent in the year after the central palm was found diseased, for a net loss over three years of slightlyover 1 per cent, this increasing in time. Early infection or infection in patches is thus more costly than late or sporadic infection.
NSTL
