Plant Doctor Archive

 I HAVE trouble with stem grubs invading my biennial lavateras. Have you any suggestions for controlling this? It causes dieback, which spoils the look of the shrub.

  IT’S probably the larvae of a moth that’s getting into the older stems.

Perennial expert Terry Hatch of Joy Plants recommends cutting them back hard in late winter and feeding them with a general fertiliser to encourage strong new growth which is less likely to be affected.

Most lavateras tend to weaken as they get older, which leaves them more prone to attack, so it’s a good idea to replant them every few years. You can take cuttings in early summer from strong new shoots — they root quite readily — and have a ready supply of fresh new replacements.

Weekend Gardener, Issue 179, 2005, Page 30

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• Content or advice may be out-of-date.