Ask the Plant Doctor

Our Plant Doctor Andrew Maloy dispenses expert advice every issue on solving common garden problems.

Lacklustre lime

My young lime tree isn’t growing very well and now has brown patches on some leaves. Can you help?
K Hillman, Auckland

The shape of these leaves is typical of kaffir lime, Citrus hystrix, also known as makrut lime, from Southeast Asia. It’s not the type of lime you pop into drinks or use in desserts, though. With kaffir lime, the leaves are used more than the gnarly, lumpy-looking, rather sour fruits. You don’t eat the leaves, but whole or chopped they add flavour to Asian-style curries and stir fries. Several things could cause the symptoms on your plant. The brown leaf tips could be disease caused by the wet summer weather but the overall yellowing of the foliage is of more concern. Your plant is lacking in nutrients, so give it a feed with a citrus fertiliser, or even a general garden fertiliser if you have one handy, which should bring some green colour back into the leaves and encourage new growth. A spray with a copper fungicide such as liquid copper two or three times a year should help prevent damage from the fungal diseases which can affect some citrus in Auckland’s humid climate.

For more advice on kalanchoe and ornamental grape read the full story in our July 2023 issue.

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