Plant Doctor Archive

Thorny lemon tree

My 81/80-year-old parents who live in Orewa HBC have a small lemon shrub (maybe a meyer approx 3 years old and which in the past has had a few lemons) which has mysteriously developed a complete crop of extremely sharp thorns — approximately 3 cm each in length. The affected wood is all new/green growth whilst the only remaining conventional-looking branch appears to be dying. The entire bush is a maze of very sharp thorns.

The thorny growth that has appeared is from the rootstock onto which the meyer lemon is grafted. This growth is shooting up from below the graft and needs to be removed. The rootstock has a more vigorous growth habit than the meyer lemon and does not bear productive fruit. As you have described, it also reduces the vigour of the lemon.

Remove the thorny growth. Now is a good time to feed citrus with a specially blended citrus fertiliser.

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

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