Trichoderma Fungi for Forestry

Bio-inoculants are being used with great success in the NZ forestry industry and in some overseas countries, developed and commercialized by the Bio-Protection Research Centre at Lincoln University, one of New Zealand’s Centres of Research Excellence (CoREs).

Bio-protection is defined as the exclusion, eradication or effective management of risks posed by weeds, pests and diseases to New Zealand’s economy, environment and human health. The Bio-Protection Research Centre is a CoRE, funded by the Tertiary Education Commission, comprising four partner institutes – Lincoln University, Massey University, AgResearch and Plant & Food Research. Dr Robert Hill is a full-time senior researcher into the sampling, identification, multiplying and commercializing the use of Trichoderma, a group of fungi, as inoculants to prevent some major diseases of economically productive trees, Pinus radiata and Acacia mangium.

Production trees like radiata pine are subject to diseases of the root system and the foliar system which can slow growth and cut wood yields in form and in volume. For instance, pines get needle blight such as dothistroma. In general terms the healthier the individual tree, the less prone it is to pests and diseases. The tree has many mechanisms to fight disease, which include plant cell associations with micro-organisms, especially in the root system. A beneficial micro-organism can enhance tree vigour, as shown by seedling survival, growth rate and desirable wood characteristics.

There are about 150 known species of Trichoderma fungus and many thousands of different strains, some of which live in tree root associations. Dr Hill has specialised in finding and using those rare and unusual ones which can give huge benefits when associated with seedlings of production trees. Grown in isolation and then applied in coatings to the tree seeds before planting, the selected Trichoderma can, for example, fire up the plant’s own defence system, increase the efficiency of photosynthesis beyond the cost of hosting the Trichoderma or perhaps make the plants more tolerant to adverse effects like drought and salinity.

Dr Hill digs in the ground for healthy root samples under very healthy trees for different Trichoderma, which are then isolated from the roots and multiplied up in the laboratory – he says they are easy to grow and mass-produce. In one corner of the CoRE laboratory at Lincoln he can grow enough of a beneficial Trichoderma (or combination) to inoculate all the pine seeds planted every year in NZ.

One product has already been commercialized, called ArborGuard, and has been used by tree nurseries. However even better, more affordable Trichoderma inoculant mixtures are on the way.

Dr Hill says the cost of inoculation is modest and the gains far outweigh the cost.

For instance, ArborGuard has been shown to reduce the death of pines from the intractable disease Armillaria by around 30%.

A new collaborative research project has begun on beneficial endophytes for the control of major foliar diseases of pines.

Dr Hill has worked for four years on a collaborative partnership with two Malaysian forestry companies to use inoculants to enhance Acacia mangium seedling establishment, growth and health and to control Ganoderma root rot disease in the plantation forests using selected local Trichoderma isolates.

After two years a production facility at a Malaysian nursery was producing sufficient inoculum to treat up to 40 million seedlings annually. Survival and quality improved markedly and fungicide applications ceased.

One year after planting out, the inoculated seedlings are greatly outperforming their untreated neighbours. Mortality rate from diseases is 30% lower and the treated seedlings are larger and healthier.

“Treated seedlings grow into trees which are significantly taller with increased trunk diameters, which have thicker canopies, which shade out weed competition and suffer less from leaf drop. This means an increase of wood volume up to 50% and possibly shorter plantation growth periods between planting and harvest,” he said.

The Malaysian work has attracted interest from other Southeast Asian countries, where the best locally sourced endophytic root fungi will be isolated and used for soil inoculation.