Poinsettia - fungus gnat injury at stem base

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Poinsettias are susceptible to many root rot organisms, but injury from fungus gnat feeding is frequently misidentified as a root rot. Potato slices pressed into the surface of the growing mix can be used to attract and more easily detect the larvae. The flies may be monitored with yellow sticky cards. Geraniums, poinsettias, vinca (Catharanthus) and ivy seem to be especially prone to infestation.

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