Crop growth enhancement and disease control using nursery-inoculated Trichoderma root endophytes isolated from local healthy plants

Abstract

A novel approach to the challenge of selecting the most effective growth-promoting and disease suppressive Trichoderma isolates has been used successfully in a range of forestry and agricultural crops both in New Zealand and Southeast Asia. The approach targets roots from exceptionally healthy representatives of a wide variety of wild and cultivated plant species growing in the locality of the crop. Root fragments from selected host plants are washed, surface sterilised, and Trichoderma root endophytes growing from within roots are isolated in pure culture. Isolates are then tested on the crop plant of interest to select the most effective for growth promotion or disease suppression. Inoculation of seed or growing medium before seed-sowing or setting of cuttings ensures very early colonisation of crop roots by Trichoderma and has proved to be a practical and cost effective strategy. Nursery trials to select the best Trichoderma isolates have been based on seed germination, seedling establishment, growth rate, general health and the proportion of seedlings meeting specification for sale (by 50% or more) in New Zealand and SE Asia. Nursery inoculated stock has also been monitored following field plantation. Benefits include increased growth (up to 15%) and reduced mortality from diseases (often by greater than 30%).