Preliminary trials on Fungicides for Management of

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Preliminary trials on Fungicides for Management
of the Daylily Rust Pathogen Puccinia
hemerocallidis
James W. Buck and Jean L. Williams-Woodward Diseas
es of Ornamentals Department of Plant
Pathology University of Georgia
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Related rusts on other ornamental plants
Puccinia arenariae cut flower Sweet William
(Dianthus barbatus) Propiconazole and
myclobutanil
Puccinia horiana Chrysanthemum white
rust Propiconazole and myclobutanil (complet
e control reported by Dickens 1991)
Puccinia pelargonii-zonalis Geranium chlorothal
onil (Daconil), myclobutanil (Systhane), and
mancozeb (Dithane) (complete control reported
by Jeffers 1998)
Myclobutanil reported as a curative agent for
Chrysanthemum white rust (Bonde et al. 1995)
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P. hemerocallidis is considered a
quarantine-significant pest Daylily zero
tolerance
Unlike many studies with wheat rust etc., not
concerned with yield of an edible crop Concerned
with obtaining clean plants for sale
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Daylily Rust Pest Alert - National Plant
Board http/www.aphis.usda.gov/npb/daylily.html
USDA sponsored New Pest Advisory Group (NPAG)

• - stop sell when rust is found
• guidance be given to nurseries as to control
  measures
• removing and burning foliage of infected plants
• once good fungicidal treatment is determined.

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National Plant Board advise rotation of systemic
and protectant fungicides

• Systemic Fungicides suggested for control
• myclobutanil Systhane, Eagle
• Triadimefon Bayleton, Strike
• Propiconazole Banner Maxx
• Azoxystrobin Heritage
• Flutalonil Contrast, Prostar
• Protectant/Contact fungicides suggested for
  control
• Chlorothalonil Daconil, Thalonil
• Mancozeb Dithane, Fore,
• Pentathlon, Protect

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Moisture dew, irrigation (4 hours or more)
Germination
Spore lands on leaf
Spore penetrates daylily leaf
Production of orange lesions
Infection (growth in leaf)
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University of Georgia Fungicide Trials

• Rust infection followed by single treatment 1 day
  later
• Rust infection followed by single treatment (1 to
  7 days later)
• Lab assays to determine which products kill
  spores
• Continuous inoculum pressure with fungicide
  applications
• every 7- days

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1. Rust infection followed by single fungicide
treatment
-rust spores collected from infected plants
and sprayed onto daylily (greenhouse exp.) -3
plants per treatment -24 hour infection period at
100 relative humidity then plants maintained in
greenhouse -Apply fungicides once with hand-held
spray bottle -Count rust pustules on six leaves
per plant (9 to 21 days after infection) -five
trials completed (varying fungicide rates)
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Note Heritage in this trial without added
wetting agent
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Note very low disease pressure, all gave good
control
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Note dropped Banner Maxx and Contrast Very high
disease
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2. Rust infection followed by single treatment
of Heritage or Bayleton (0 to 7 days later) -24
h infection period for rust to establish (100
RH) -Fungicides applied at 4 oz/ 100
gallons -Used a hand-held sprayer to
run-off -plants sprayed once, rust pustules
counted on marked leaves three weeks later
Fungicide applied at one of these days
Day 21
0
1
3
5
7
Inoculate
Evaluate
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3. Repeated fungicide applications under
constant disease pressure
-greenhouse bench experiment (contained) -5
plants per treatment, 20 treatments -fungicides
applied weekly with hand held sprayers (except
2 wk interval between first two
sprays) -naturally infected daylily were
interspersed among treated plants (41
ratio) -rust pustules on marked leaves counted
weekly
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Class 1 (NPB) Systemic Fungicides
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Class 2 (NPB) Broad-spectrum protectants
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Disinfectants
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Zerotol (disinfectant)
BAS500 (Insignia not available yet)
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4. Do the fungicides kill the spores?
1. Myclobutanil (Systhane) and propiconazole
(Banner Maxx) -No affect on spore germination
2. Flutolanil (Contrast) and triadimefon
(Bayleton) approximately 50 of the spores still
germinated after a 24 hour exposure to the
fungicides (different concentrations)
3. Azoxystrobin (Heritage), chlorothalonil
(Daconil), mancozeb (Dithane) No germination of
spores after 24 hour exposure
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Conclusions
Single application (inoculated plants) -all
fungicides significantly reduced disease except
myclobutanil (Systhane) in one
trial -chlorothalonil (Daconil) and mancozeb
(Dithane) worked well at full and half
rates -triadimefon (Bayleton) and azoxystrobin
(Heritage) (with surfactant) worked well at
full/half rates
Single application 0 to 7 days after infection
(inoc. plants) -best control when Heritage or
Bayleton applied within 1 day of
infection -shows need to clean plants and prevent
further infection
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Multiple applications at weekly intervals
natural infection -very good control with BAS500
(8 oz), Banner Maxx (8 oz), Heritage (2 and 4
oz), Contrast (3 oz), Bayleton (2 oz) -very good
control with broad-spectrum protectants Kocide
(0.75 lb), Daconil (1.4 lb), Manzate (1.5
lb) -disinfectants gave poor control under
continuous inoculum pressure
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• Recommendations -Commercial Grower
• -Hobbyist
• Practice good sanitation
• Alternate between class 1 (systemic) and
• class 2 (protectant) fungicides
• Practice good sanitation

-Under low disease pressure all the traditional
fungicides gave fairly good control -myclobutanil
could be an exception -With a lot of disease
pressure fungicides will not be as effective
2001 Georgia Pest Control Handbook Online at
http//www.ent.uga.edu/pest2001/
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Future Work

• Additional work on fungicide timing and control
• Use of fungicide dips (bare root material) and
• drenches for control
• Survival of the pathogen (in plants/on plants/on
  debris)
• Additional products/alternatives
• - acidic electrolyzed oxidized water