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Michigan State University alert

  • Subject: Michigan State University alert
  • From: ShayDguy@aol.com
  • Date: Tue, 30 Oct 2001 08:09:22 EST

A new issue of the Michigan State University Landscape Crop Advisory Team
Alert has been posted at

Below is one article of interest to perennial gardeners who may not wish to
read the entire alert.

Daylily rust has arrived
Jan Byrne, Diagnostic Services

Daylily rust is a new disease on daylilies, and in the last week it was
found at two locations in Michigan. The disease was first found in Georgia
in August 2000 and, shortly thereafter, was confirmed in Florida, Alabama
and South Carolina. The disease has continued to spread and, this year it
has been confirmed in at least 24 states including the nearby states of
Illinois, Pennsylvania, Ohio and Indiana.

The disease caused by the fungal pathogen Puccinia hemerocallidis, is a
major concern to propagators, nurseries and home gardeners. The disease
causes lesions on the foliage and completely kills foliage on especially
susceptible cultivars. Researchers do not know whether or not tubers can be
infected. Once the disease is established, intensive scouting, removal of
infected foliage and regular fungicide applications are all needed to
control the disease. The Michigan Department of Agriculture is likely to
invoke quarantines restricting the sale of infected plant material at

There is not a lot of information known about the biology of this pathogen.
The fungus has a short incubation time, spores are produced within 7 to 14
days after the foliage is infected, and the spores are then spread by wind.
The pathogen has other hosts (Patrinia spp. and possibly Hosta spp.) but
does not need them to complete its lifecycle. The ability of the pathogen to
overwinter or survive on infected plants throughout a Michigan winter is not
known. More information about the disease and images of the symptoms are
available at two web sites:
www.ces.uga.edu/agriculture/plantpath/daylilyrust.html and

Chemical control of the disease is still under investigation. Trials
conducted by Dr. Williams-Woodward at the University of Georgia found that
Daconil Ultrex (chlorothalonil), Fore (mancozeb) and Heritage (azoxystrobin)
applied with a surfactant are effective when applied prior to inoculation.
The number of times Heritage can be applied is limited, so this product
should be rotated with other effective products – consult the label for more
details. Plants suspected of having daylily rust can be submitted to
Diagnostic Services (517-355-4536). This disease can be confirmed relatively
easily and results are usually faxed back on the same day that samples are

Martha M Ferguson
Extension Program Coordinator
Michigan State University Extension-Oakland County
1200 N Telegraph Rd
Pontiac MI  48341

(248) 858-0900 phone
(248) 858-1477 fax

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