Tree expert advises using sugar to improve chances of plant survival

Sugar could be the answer to ensuring the survival of new and mature trees in our parks and green spaces, a leading tree expert has revealed.

Image: HW
Image: HW

Dr Glynn Percival said 30 years of research have done little to reduce death rates among new trees, which are currently 30-70 per cent. People forget roots are not only for anchorage but nutrient storage, he added. Poor root systems deplete storage reserves by up to a third, starving trees to death.

Percival, from the University of Reading, told the Palmstead Nurseries Survival of the Fittest conference that he spent eight years prompting root growth through agents from bio-stimulants such as compost tea and seaweed to water-holding gels.

"But we have found through our research and others' that there are few consistent benefits on newly planted trees. I'm not saying they don't work, they do, but the problem is we found we got the cycle of specificity," he said of products with a "cocktail" of ingredients that make the process as random as playing roulette.

But when he added 30 grams of sugar per litre of water poured on new tree roots, he was astonished at the root stimulation. Adding sucrose - "basically Tate & Lyle from Asda" - led to good water retention, better nutrient uptake and more root growth, he said.

It "switched on" certain genes that jump-started root growth such as storage and defence genes. He said sugar is the universal energy molecule and could help all plants from a grass blade to a mature tree. It is water soluble, non-toxic and cheap, he added.

He cited a well-known case of a mature treaty oak in Austin, Texas, which was poisoned with enough herbicide to kill 100 trees. Conservationists replaced the soil around the roots and injected sugar to ensure the tree's almost miraculous survival.

Palmstead Nurseries marketing manager Nick Coslett said: "Using sugar is a bit like the Red Bull treatment - it gives trees wings. The trouble with so much research is it never filters out to the industry and it's crucial for the media to highlight new science and thinking."

Latest research - Benefits of mulching

"If you want to enhance survival of trees, mulch them - it's the simplest thing you can do to improve survival rates," said Dr Glynn Percival.

After trialling mulches on transplant-sensitive containerised beech, he found survival rates jumped from one in 10 without mulch to six in 10 with a pure mulch such as cherry chippings.

Freshly-chipped is better than composted mulch because it is higher in sugar and better at helping to suppress diseases. Researchers in California used pure mulch on eucalyptus to offer "100 per cent control of Phytophthora".

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