SA Power Networks latest Stunt – More Answers please…

The ABC has provided timely news on a practice about to be applied to trees in South Australia with the effect of stunting their growth. A novel concept and good news coverage, but it leaves many questions unanswered and in a state that makes blunder after blunder it would be fascinating for any horticultural readers of RM to share their views on this development.

By Isabel Dayman ( RM has taken the liberty of correcting ABC grammar – “powerlines”  is not a word.

SA Power Networks is looking at options so it doesn’t need to trim trees under powerlines.

PHOTO: SAPN says chemicals being used to slow tree growth are safe. (ABC News: Isabel Dayman)

(RM question: what is the chemical being used and can you please validate the basis of this claim?)

A fungicide used to stunt plant growth could be the key to reducing the need for often unsightly tree trimming under Adelaide’s power lines.

SA Power Networks [SAPN] is trialing the use of chemical injections in the City of Campbelltown, in an attempt to reduce the length of branches and reduce the need for pruning.

“We have a large number of trees which are actually unsuitable for planting under power lines, which have been planted in South Australia for many years,” SA Power Networks spokesman Paul Roberts said.

“[The fungicide injection] is injected into the soil around the roots … the tree takes it up from the ground, and it gets into the growth system and limits the tree’s production of gibberellin, which is its growth hormone.

“It’s been used extensively in the United States and also in the horticultural industry in South Australia.

“For example, the mangoes, nuts and avocados you buy in Australia – those trees have actually been treated with this growth slower.”

Mr Roberts said the trial had so far been successful for most of the species involved in the testing.

“We’ve treated [seven] species of tree and we’ve seen [a reduction of] about 55 per cent in growth in some of the species.”
SAPN trims thousands of trees around South Australia every year as part of its maintenance program, to reduce bushfire hazards and the risk of outages caused by falling limbs.

Mr Roberts said trimming was unpopular in some areas as it damaged the appearance of larger trees.

“We’re looking at [the use of fungicide injections] as an alternative in areas where there’s a greater sensitivity to the appearance of trees, such as in tourist and high-amenity areas in townships,” he said.

“We’re very conscious of the community’s desire to balance aesthetics as well as get safety and the reliability of power supply right.
“We’re hoping that the use of a growth slower will reduce some of our tree trimming, although we’re always going to have to trim trees.”

The fungicide injection trial is set to run for another two years before the final results are analysed.

SA Power Network says:

Vegetation and trees form a key part of our urban and rural landscape and provide a wide range of aesthetic and environmental benefits and values.

There are however risks associated with trees in relation to their proximity to power lines.

SA Power Networks delivers electricity to approximately 840,000 residential and business customers across South Australia and our network includes more than 71,000km of overhead power lines.

SA Power Networks is required by legislation to inspect and clear vegetation from around power lines at regular intervals of no more than three years.

Managing trees and vegetation near power lines is critical to ensuring community safety, mitigating bushfire risk and providing a reliable and safe supply of electricity to our customers.

For more information about our vegetation management program, please contact us on 13 12 61. You can also contact the Office of the Technical Regulator on 8226 5500.

It provides more details but no specifics on the chemicals or pesticides proposed, in its 2014 draft discussion paper:

Growth inhibitors:

  • Use of pesticides and growth retardants to inhibit regrowth (RM: What pesticides, what retardants?)
  • Understand appropriate sites for application and use in consultation with Local Government and the community