Source:  NCSU COOPERATIVE EXTENSION, 8/17/21


July is the month when mum producers start seeing wilting plants due to Pythium root rot, with more cases turning up in August and September. If you have not been taking steps to prevent losses to this disease, there may still be time to forestall some losses.

Pythium species are fungus-like “water molds” that can infect a wide range of herbaceous plants. The usual point of attack in mums is the root system. Roots turn brown and the exterior portion can slough off leaving only the central vascular bundle (“rat tailing”). Above ground, the foliage wilts as a result of loss of root function. Leaves do not develop spots or turn yellow unless other problems are also present. From the roots, Pythium can move up into the stem and cause reddening of the woody tissue at the base, lower stem rot, or even vascular streaking that could be confused for Fusarium wilt. On occasion, Pythium will cause a full-blown stem and foliage blight in mums.

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