Plant Doctor Archive

Viburnum leaves turning brown

I recently planted a Viburnum 'Emerald Beauty' in a semi-shaded spot in my garden. A couple of weeks after planting the leaves started to droop. I gave it lots of water and some liquid fertiliser and it perked up, but some of the leaves are now turning brown. I can't see any sign of pests. Other plants in the same bed are fine. Do you know what the problem might be?

It sounds as if your viburnum has a root disorder. It could be one thing or a combination of things causing the symptoms you describe and is a process of elimination.

Transplant shock — excessively disturbing the roots before planting — can cause wilting and leaves to shrivel. If the tree has been grown in the open ground and lifted recently, it could show signs of wilting until it recovers.

Too much fertiliser applied at the time of planting has the same effect, as does allowing the plant to dry out after planting.

The worst senario is root rot. This will cause wilting and leaves to brown and shrivel up, and there is not a lot that can be done.

If you think you may have applied too much fertiliser, you can save the plant by leaching the excess fertiliser out of the soil. You will need to water the plant for at least an hour to wash the fertiliser out.

If your viburnum dried out after planting, water regularly, depending upon the weather, until it is established. Mulching around the plant will help retain soil moisture.

If you think it may be a root disorder, there is very little that can be done. Reduce the watering, cut the plant back by about a third and see what happens. Usually, plants with root rot disorders will not recover. If the plant was purchased from a garden centre, take it back with the label and receipt; they should have a replacement policy for plants that fail to thrive.

I think that it is likely to be transplant shock and the plant will recover. If the plant has dropped its leaves, cut it back by about a third to a bud; it will come away.

Advice by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor of Resource Management.

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