A field Ganoderma trial was set up in 2001 on an oil palm field in Dolok Estate (Sei Bejangkar Division) PT. PP. London Sumatra Indonesia Tbk (Lonsum). The North Sumatra site had very serious Ganoderma incidence previously with a mean of 52% of vacant trees (assumed due to Ganoderma) plus a mean of 6% Ganoderma infection symptoms in standing trees. The trial investigated the effect of windrowing, fallowing and poisoning practices conducted at replanting on subsequent infection by Ganoderma in the replanted oil palms.
Percentage Ganoderma infection was assessed on 50 palm/plots with 4 replicates per treatment and using a split plot design with 2 main plots and four sub plots. The main plot compares windrow 1:1 (every previous row) and windrow 2:1 (alternate previous planting row / current system) and sub plots consisted of factorial combinations between fallowing and poisoning.
Seven years of observation showed that the infection in windrow 1:1 without additional treatments (no poisoning and immediate planting) resulted in up to 41% infection while windrow 1:1 with no poisoning and fallowing for 1 year resulted in infection of ca. 10%. Where palms were planted immediately on the windrow 1:1 system with poisoning, 28.5% palms were infected. The windrow 2:1 system is the usual estate practice on Lonsum estates. Treatment of windrow 2:1 without any treatments added (unpoisoned-immediate planting) showed infection ca. 28% at the end of 2009 compared to 32% infection in the treatment of windrow 2:1 system (combined with poisoning and immediate planting). In contrast where treatment windrow 2:1 was combined with poisoning and fallowing for a year, only 3% infection was observed and infection in the treatment of fallowing without poisoning plus windrow 2:1 system also remained low (6%).