Raising trees with less chemicals

SCIENTISTS HAVE REDISCOVERED PREVIOUSLY USED techniques that result in seedlings and young trees forgoing regular doses of chemicals in favour of natural soil agents that make them grow healthily and quickly.

For the past 30 years, it has been common practice to use chemical treatments to combat disease on seedlings and provide nutrients to help them grow better once they are planted out.

But the Forest Growers Research conference in Christchurch heard that certain types of naturally-occurring Mycorrhiza fungi in the soil promote vigorous growth in the root system and protects against diseases at the same time.

This information isn’t new – it was discovered in the 1950s and was used by nurseries until the 1980s, when government withdrew funding for ongoing research after some major setbacks, and chemicals became more widespread as a result.

With new research funded by FGR, scientists have now pinpointed the active parts of the Mycorrhiza that promote improved growth and health, and have tested these at nurseries with good success, leading to the withdrawal of all chemicals by the end of the tests.

Scion’s Simeon Smaill told the conference that even when planted out, the seedlings raised in this way continued to outgrow those raised with chemical use, which reduces costs and conforms to FSC rules about limiting chemicals in registered forests

Dr Smaill says the next stage in the programme is to look at other nursery systems to see how these can be upgraded and improved, so they can be combined with the Mycorrhiza research to help nurserymen enhance their operations. Among these is introducing more automation to propagation and growing processes.

Meanwhile, parallel research undertaken by Lincoln University has shown that raising trees under this natural soil regime has shown that trees are likely to benefit well after planting out, boosting growth by as much as 20%. Dr Helen Whelan says eight large field trials with Radiata Pine plots of 10 hectares each will be undertaken in 2018 to validate the best root treatments.

NZL