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Bioprotection for Foliar Diseases and Disorders of Radiata Pine

Foliar diseases and disorders are the largest cause of economic loss for the New Zealand forestry industry. In order to alleviate losses caused by existing diseases and also to reduce potential impacts of biosecurity threats, work is being conducted to establish a long-term symbiotic relationship between Radiata pine and beneficial microbes. The main focus will be to enhance tree vigour and induce systemic resistance against foliar diseases by using endophytes and elicitors. Induced resistance can effectively `immunise' trees from a variety of diseases/disorders, because it causes a broad spectrum activity response by the plant (analogous to vaccination). This is part of a larger project involving Plant & Food Research, Scion, Massey University and The Tree Lab led by Dr Robert Hill from the Bio-Protection Research Centre, Lincoln University.

Over 500 new Trichoderma root endophytes have been isolated from healthy plants throughout New Zealand. They are presently being screened in assays against Diplodia and terminal crook disease. Activity against Dothistroma and red needle cast (RNC) will be evaluated in assays and plantation trials.

Screening novel Trichoderma root endophytes for enhanced nursery performance with P. radiata seedlings

Approximately 200 new endophytic Trichoderma isolates were applied to containerised P. radiata immediately after seeding at the PF Olsen container Nursery, Waiuku. Each isolate was grown on a peat/wheatbran medium for two weeks. Spore suspensions were prepared in water at a rate of 106 colony forming units/ml and applied to seed trays immediately after sowing. Treatments included single isolates and selected mixtures. Seedling establishment, growth, and health were monitored to determine the most effective isolates. 28 treatments caused significant increases in seedling growth compared to untreated controls after 5 months (below).

Trial results

Establishment of new forestry plantation trials

Wharerate trial site

Trichoderma-innoculated tree stock trials to assess tree vigour and resistance to diseases like Dothistroma and red needle cast (RNC)

Three sites were selected in the Wharerata forest near Gisborne (Juken New Zealand Limited). P. radiata seedlings inoculated with a Trichoderma mixture showing superior growth promotion and disease suppression were planted out. Seedlings were planted in blocks along with control treatments in areas historically subject to high RNC incidence.

Four trial sites were also chosen and planted in the Pinnacles forest (PF Olsen Ltd) near Rotorua. These trials will be assessed for disease and growth at appropriate intervals; already reduced mortality is being demonstrated.

Subsequently, over 15 new plantation trials have been established at sites throughout New Zealand to test the best root endophyte treatments for enhanced tree growth and disease control. More field trials will be established in the 2015 planting season to evaluate existing and selected new Trichoderma mixtures.

Trial results graph

The Trichoderma root endophyte mixture (T) recorded 2 years after trial establishment at three sites in the Wharerata Forest significantly increased tree growth (height).

If you are interested in adding a Trichoderma endophyte trial to your 2015 planting programme please contact Dr Wei-Young Wang (wei-young.wang@pfolsen.com) at PF Olsen Ltd who can assist you with the trial design and planning.

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Correction

In this article titled "Bioprotection for Foliar Diseases and Disorders of Radiata Pine" from the May issue of Wood Matters we incorrectly referenced forest company Juken New Zealand Limited as Juken-Nissen NZ Ltd. We apologise for this error and have made the correction in the on-line copy.