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How to Kill a Tree Stump

Posted in Garden Advice on June 28, 2021

Trees are wonderful. They spend their lives sequestering carbon from the atmosphere into wood, releasing oxygen for us to breathe. But all good things must come to an end. Even the bristle cone pine is not immortal and eventually dies. Although it gives it a good go, some surviving several thousand years. Other trees just get too big for their garden or are in the way of the new house extension. In these cases, and others, the trees need to be cut down.

Whatever way a tree is cut down it is likely to leave a stump and an extensive root system; most trees will have roots that are 20-30% of the mass of the trunk and branches, they are likely to spread 2-3 times as far from the trunk as the canopy spreads. Most of the root system will be in the top 45 cm of the soil where the most nutrients are, but there maybe large structural roots that go much deeper and anchor the tree in the soil.

These trunks and large root systems still have lots of energy, and given the chance, will re-sprout and send up suckers (shoots from roots). Left alone you might get rid of one large tree in return for a forest of small trees, even if the stump is ground out. Grinding the stump out will remove the trunk and top of the main roots but remaining roots will probably still re-sprout. To prevent the remaining roots re-sprouting and to promote the natural rotting and breakdown of the roots, it is necessary to kill the stump with herbicide that will kill the stump, but not harm the desirable plants whose roots may be close to, or intricately entwined with, the tree roots.

How to Kill the Tree Roots and Prevent Re-Sprouting

Kiwicare Weed Weapon Stump Stop Gel is formulated to effectively kill tree roots without causing harm to surrounding plants.

Cut the tree down and immediately paint Weed Weapon Stump Stop onto the whole cut surface of the stump. The sooner the gel is applied to the cut the more effective it will be. The herbicide is then drawn down into the vessels in the stump and transported to the whole root system.

For stumps that were not treated on cutting down they can be cut further down or have cuts or holes created in the stump, and then the Weed Weapon Stump Stop applied immediately.

How to Encourage Natural Rotting of the Tree Stump and Roots

Once dead the stump and roots will naturally begin to rot and breakdown, returning organic matter and nutrients to the soil. However, large stumps can take many years to breakdown. You can speed up the rotting process by:

  • Cutting or drilling holes in the top of the stump so that water pools.
  • Cover the stump with compost, lawn clippings or any organic material that will more rapidly compost and breakdown. This adds the micro-organisms (bacteria and fungi) that will start the breakdown the stump, it insulates the stump to keep it warm, and keeps the stump moist. All this encourages more rapid breakdown.
  • Old woollen carpet is a useful way of weighting down the compost and providing extra insulation.
  • LawnPro D-Thatch can be added to the stump and/or compost to boost the activity of the bacteria and fungi that will breakdown the stump.
  • Alternatively, a little nitrogen fertiliser such as ammonium sulphate and ammonium nitrate can be added to the stump or compost to feed and encourage the micro-organisms.

This process may reduce the time for a stump to breakdown by as much as half.

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