Plant Doctor Archive

Ailing blue spruce

We have a blue spruce which has been in our front garden for about ten years now. It has been growing exceptionally well so far but has suddenly developed a lot of brown on it, mainly from the ground up. It is still growing fairly well but it just doesn't look very nice. A few weeks ago we had a lot of continuous rain here in Canterbury but I thought it would have liked that, being an alpine type of plant.

It sounds as if your spruce has some sort of root disorder, possibly phytophthora. It is quite common when there has been a period of dry weather and then wet weather. Plants from the conifer family are susceptible to root disorders where drainage is inadequate.

Cut back the infected foliage and dispose of it in the rubbish bin or burn it to stop the disease spreading. Ask your local garden centre if they have, or can get, a fungicide called Aliette. It is very effective on phytopthora but has more preventative properties but also limited curative properties. Once a plant is infected there isn't a lot that can be done, and often plants require removing and destroying.

Good drainage is essential. If drainage is not good, it can be improved by creating raised beds.

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

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