Enhancing health and vigour of Acacia mangium by nursery inoculation with selected root-endophytic Trichoderma isolates

Abstract

Root-endophytic Trichoderma isolates were obtained from root samples taken from a wide variety of exceptionally healthy plants in the locality of the Samarakan Nursery, which supplies Acacia mangium seedlings for the Planted Forest Zone (PFZ) in Sarawak, Malaysia. Nursery trials based on approximately 50 single isolates and selected mixtures of these were conducted between 2008-2009. Root-endophytic Trichoderma isolates were inoculated by applying an aqueous suspension of conidia to the growing medium at the time of seed sowing. The most effective treatments resulted in an increase in productivity of >66% in seedlings meeting specification for planting out into the PFZ. These results were validated in large-scale trials conducted in 2010 which showed the same productivity increase from the best isolates. A trial examining the effects of mixing the Trichoderma inoculum into the growing medium before seed sowing compared with application of a conidial suspension (as in the initial trials) demonstrated that both delivery methods gave exactly the same results. Nursery inoculated trees have shown 30% reduction in mortality from diseases and increased growth (up to 15% greater tree height and diameter) in PFZ plantations. Trichoderma inoculation is now standard operating practice at the Samarakan Nursery, replacing multiple sprays of fungicide cocktails and reducing the time taken for seedlings to meet specifications for planting out into the forest from 108 to 90 days. This project is an ongoing collaborative venture between Grand Perfect Sdn Bhd, Sarawak, Malaysia and the Bio-Protection Research Centre, Lincoln University, New Zealand.