HAVE a garden full of daylilies and in some areas the plants are
dying off. The backs of the leaves develop fine rusty-looking channels,
then the leaves turn yellow and die. Several months ago I found
aphids down in the inner leaves and sprayed with Orthene. Some plants
I chopped off and sprayed and these have come away again but are
now showing dryish tips again. I am now wondering if it is mites
or some soilborne disease.
are generally not prone to pest or disease problems, but, in certain
conditions, there are several fungus diseases, including rust and
leaf spots that can affect them.
The symptoms you describe
suggest fungal disease rather than mites or aphids. The cool, wet
weather we experienced in spring and early summer have encouraged
fungal problems in plants that are normally relatively disease free.
Clearing out the affected
leaves as you have done is a good idea, as is cutting out about
two-thirds of all the foliage in winter to reduce the risk of disease
overwintering and to encourage healthy new growth in spring. Now
that the weather has improved, you may find the problem goes away
and new growth is disease free, but you could spray with a fungicide
such as Bravo, Fungus & Mildew Spray or Fungus Fighter. Follow the
Daylilies do best in
free-draining soil, exposed to lots of sun and fresh air and are
more likely to suffer disease if shaded and sheltered by nearby
shrubs or if their leaves remain damp for long periods. So it may
pay to prune nearby shrubs to increase air flow and exposure to
sun, if necessary.
Gardener, Issue 164, 2005, Page 24
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.