Fusarium Wilt and Stem Rot of Chrysanthemum
Tom Creswell, P&PDL Director, Purdue University
As cooler weather approaches a bright spot
in the otherwise fading landscape is the Chrysanthemum. Chrysanthemum
producers sometimes run into a troublesome disease known as fusarium
wilt and stem rot. The fungus (Fusarium oxysporum) invades
the plants through the roots, eventually entering the water conducting
vessels of the plant and plugging them so the plant can no longer
take up water. Early symptoms include yellowing and wilt. When
stems are split they show red to tan discoloration inside and
eventually the stem outside shows white tufts of spores.
It is common to see one dead plant in a multi-plant pot or to
see a single branch wilting and showing leaf death. Eventually
the entire plant dies as the infection spreads. The fungus can
be spread on contaminated pots, tools and anything that moves growing
media. It also produces spores that are resistant to drying and
cold and can survive long periods in soil or plant debris, so cleaning
up greenhouse and outdoor mum growing areas is critical to preventing
a repeat of the same problem in the next crop. Fungicide treatments
have to start early (soon after transplant) to be effective.
The disease is not often a problem in the home landscape because
infected mums usually show symptoms and are discarded before they
reach retail stores.