Trichoderma root endophytes enhance plant health and vigour

Abstract

Plant health depends on associated fungi. Symbiotic Trichoderma root endophytes promote crop growth, activate defences, improve nutrition, increase tolerance to abiotic stresses and control pathogens through antibiosis and mycoparasitism. Control of Armillaria disease in New Zealand (Kiwifruit and Pinus radiata) with selected Trichoderma mixtures led to the development of commercial products DRH and ArborguardTM (AG). Inoculum application rate, timing and mode of application for AG were optimised in commercial forest nurseries. Seed coating was the most cost-effective system for both containerised and soil bed nurseries. In forest plantation trials AG treatment reduced mortality from Armillaria disease by 20-50% after two years. It was found that ectomycorrhizal colonisation of P. radiata roots was not reduced by AG and that a close symbiotic relationship between the roots and Trichoderma was associated with increased seedling vigour. Increased resistance to Diplodia pinea was induced in P. radiata seedlings by particular Trichoderma isolates. Root initiation and subsequent growth and health were stimulated and enhanced by specific Trichoderma isolates in cuttings of a variety of plant species. These successes resulted in an invitation in 2008 to evaluate the utility of Trichoderma bio-inoculants in the Planted Forest Zone of Sarawak, Malaysia. Several constraints led to a decision to only isolate Trichoderma from within the roots of very healthy local plants. These isolates were trialled in a large commercial nursery growing containerised Acacia mangium. The best isolates gave a 66% increase in the number of seedlings meeting nursery specification and large scale validation trials gave identical results. Plantation trials resulted in a 15% increase in growth and a 30% decrease in disease mortality by Trichoderma-inoculated trees. A purpose-built Trichoderma mass production facility now supplies the whole nursery and operational practice has changed from multiple fungicide sprays to Trichoderma inoculation at seeding resulting in multi-million dollar economic benefits annually.