Summary Pest Risk Assessment for PHSI interceptions - DOC by Sfusaro

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									PHSI Interception PRA for Puccinia hemerocallidis update prepared by David Jones, CSL; 17/02/05;
First PRA completed on 10/01/02; PPP 9860

                                                                        05-11627 (rev of 02-9179)
                                                                                  P PM point 8.2




  SUMMARY PEST RISK ANALYSIS FOR UK INTERCEPTIONS


Question                                             Answer
1. Name of fungal pest:
Teleomorph: Genus, species, var., f.sp.              Puccinia hemerocallidis
Synonym(s): Genus, species, var., f.sp.              Dicaeoma hemerocallidis, Aecidium
                                                     patriniae, Puccinia funkiae, Uredo hostae,
                                                     Puccinia hostae
Anamorph: Genus, species, var., f.sp.
Synonym(s): Genus, species, var., f.sp.
Common name for disease                              Daylily rust
Special notes on taxonomy or nomenclature            Transchel in 1913 (Hiratsuka, 1992) was the
                                                     first to prove the relation between the aecia on
                                                     leaves of Patrinia rupestris and P.
                                                     scabiosaefolia to the uredinia and telia on
                                                     leaves of Hemerocallis minor. Hiratsuka in
                                                     1938 was the first to report successful
                                                     inoculations between the aecial state of this
                                                     species on Patrinia scabiosaefolia and the
                                                     uredinial and telial states on leaves of
                                                     Hemerocallis disticha (Hiratsuka, 1992).
                                                     Hosta spp. have been reported as
                                                     uredinal/telial hosts in Japan (Hiratsuka,
                                                     1992). However, Hosta has been found to be
                                                     affected in the USA (Schubert and Leahy,
                                                     2001) and is now not thought to be a host in
                                                     Japan (Yoshitaka, 2003).
Primary pathogen (Y/N)                               Y
Weak pathogen (Y/N)                                  N
Saprophyte        (Y/N)                              N




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PHSI Interception PRA for Puccinia hemerocallidis update prepared by David Jones, CSL; 17/02/05;
First PRA completed on 10/01/02; PPP 9860




2. (ai) Does it occur in the UK?
No (C. Lane, CSL, 2001, pers. comm.)
   (aii) Has it been intercepted before on this host in the UK ?
 The pathogen was intercepted in 2001 and 2002 on daylilies imported from the USA.
   (aiii) Has it been recorded before on this host in the UK?
No (C.Lane, CSL, 2001, pers. comm.)
2 (b). Is there any other reason to suspect that the pest is already established in the
        UK?
No, but there has not been a comprehensive survey of nurseries growing daylilies

3. EC Directive Status? (Annex or not listed)
Not listed

4. EPPO Status? Present on Alert List

5. What are its host plants?
5.     (a). Highlight crop plants grown commercially, including those of environmental or
amenity value, in the UK (and EU/EPPO) (include figures for potential yield/quality losses):

Puccinia hemerocallidis is a heteroecious rust. Species in the genera Hemerocallis, a
common amenity plant in Europe, are uredial/telial hosts. Hosta (Liliaceae) has also been
described as an uredial/telial host in Asia (Hiratsuka, 1992). However, this has not been
proven (Yoshitaka, 2003) and the rust has never been seen on Hosta in the USA (Schubert
and Leahy, 2001). Species in the genus Patrinia (Valerianaceae) are spermagonial/aecial
hosts.

Uredospores released from Hemerocallis can perpetuate the rust on this host. Germinating
teliospores on Hemerocallis produce basidiospores capable of initiating infection on Patrinia
spp.. Aeciospores from infected Patrinia spp. are capable of initiating infections on
Hemerocallis.

5. (b). Are any of the host plants of forestry importance?
 No




                                                2
PHSI Interception PRA for Puccinia hemerocallidis update prepared by David Jones, CSL; 17/02/05;
First PRA completed on 10/01/02; PPP 9860




6. What is its present geographical distribution?
Asia: China; Japan; Korea; Russia - Sakhalin, Kuriles, Siberia; Taiwan
       (Hernández et al., 2002; Hiratsuka, 1992; Schubert and Leahy, 2001).
Australia/Pacific: Australia - Queensland (EPPO, 2002).
North America : Canada (Anon., 2002); USA - Alabama, California, Florida, Georgia,
       Mississippi, Minnesota, South Carolina, Tennessee, Texas (Schubert and Leahy, 2001)
       plus Arkansas, Connecticut, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana,
       Maryland, Michigan, Missouri, Nebraska, New Hampshire, New Jersey, New York,
       North Carolina, Ohio, Oregon, Pennsylvania, Rhode Island, Virginia, Wisconsin
       (Anon., 2002) plus Hawaii (Hernández et al., 2002).
Central America: There is indirect evidence that the rust may be present in Costa Rica as
      daylilies imported from Costa Rica have been diagnosed with the rust on arrival in
      Miami (Hernández et al., 2002; Schubert and Leahy, 2001).
Present in EU (specify countries): Not reported
Present in EPPO region (specify countries): Not reported

7. Does it appear capable of establishing in the UK/EU/EPPO?
(a) outdoors? Daylilies are commonly grown garden plants and are hardy perennials. The
rust is capable of surviving on daylily alone; no other host species is required for it to
perennate. Daylily is a common amenity plant in Europe. Daylily rust has been recorded in
climates as diverse as those in Siberia and Florida and would be expected to be capable of
establishment in the UK and the EU/EPPO region where Hemerocallis spp. are grown.
Experimental work in the USA has shown that uredospores can germinate on potato dextrose
agar between 10°C and 30°C. Germination was not observed at 4°C and 34°C and it is
thought that summer temperatures in the south of the USA may not favour infection (-Buck
and Williams-Woodward, 2001; Mueller et al., 2002). High temperatures in southern Europe
during summer may also inhibit infection.

(b) on protected crops? Daylily rust has been found on plants growing in nurseries in the
USA. The second detection in the UK in 2002 was on imported plants growing in a
polytunnel. Some plants may have been under glass or shadecloth, but there is no
information to confirm this possibility




                                                3
PHSI Interception PRA for Puccinia hemerocallidis update prepared by David Jones, CSL; 17/02/05;
First PRA completed on 10/01/02; PPP 9860




8. What is its potential likely to be as a pest in the UK/EU/EPPO? In the UK and many
other European countries, daylilies are an important component of herbaceous amenity
plantings in public and private gardens. Puccinia hemerocallidis has the potential to become
a common pathogen of daylily in the UK/EU/EPPO. Little is known of the requirements of
the pathogen, but it seems capable of infection under a wide range of environmental
conditions. Affected plants are not killed, but infection, which causes an unsightly blemish
on leaves, diminishes their amenity value and makes the plants unmarketable. Repeated
infections result in a decline in the health of plants (Williams-Woodward and Buck, 2001).
However, some daylily cultivars are reported to be resistant and the use of this material could
limit disease damage (Mueller et al., 2003). There is no information on the effect of the rust
on other hosts, but in the USA Patrinia spp are not common as ornamentals and Hosta spp.,
which have been implicated as uredial/telial hosts (Hiratsuka, 1992), are unaffected
(Schubert and Leahy, 2001).

9.      What are the prospects for continued exclusion? In Florida, new infections have
been reported to arise in as little as 2-3 days after infection on susceptible varieties of daylily
(Schubert and Leahy, 2001). However, in some plants, it has taken as long as 2-3 months
before symptoms were seen (T. Schubert, USA, 2001, pers. comm.). Symptoms on the
infected daylily first intercepted with rust did not become evident until approximately 2½
months after the plant arrived in the UK (Grant-Downton, UK, 2001, pers. comm.). Some
daylily varieties have been reported to be largely unaffected by the rust (Schubert and Leahy,
2001). Florida was the first state in the USA to have recorded the rust problem. Spread to
other parts of the USA may have occurred because either (1) plant health inspectors failed to
detect light infections, or (2) incubating infections were missed because of the absence of
symptoms, or (3) inoculum on plants initiated infections after shipment (T. Schubert, USA,
2001, pers. comm.). Because of the above, it may be difficult for overseas plant health
inspectors to certify daylily material exported to the UK/EU/EPPO to be free of the
pathogen. The plant intercepted with rust in 2001 was covered by a phytosanitary certificate.
Symptoms were not evident on arrival (R. Grant-Downton, UK, 2001, pers. comm.). Any
daylilies imported from countries where the rust has been recorded may harbour spores of the
pathogen or carry the pathogen as a latent infection. A ban on the importation of daylilies
from those countries where the disease has been recorded or the introduction of a
requirement that imported daylilies be grown in nurseries where the rust has not been
recorded in the last 12 months should assist exclusion.

No information is available on the importation of other hosts of the daylily rust into the
EU/EPPO region so risks are difficult to assess. However, imported species of Patrinia and
Hosta should be closely examined for disease symptoms.

The first interception in 2001 was on one of four plants introduced from Florida by a private
collector/grower and it is believed that this outbreak has been eradicated. In this instance, the
importer was a plant pathologist and, because of his familiarity with plant diseases and
knowledge that there was a serious rust of daylilies in the USA, he alerted the UK NPPO to
the rust problem. It is possible that infected plants from the same nursery in Florida may have
been imported by other individuals within the UK and EU/EPPO region. Therefore, the rust
may already be present in Europe.

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PHSI Interception PRA for Puccinia hemerocallidis update prepared by David Jones, CSL; 17/02/05;
First PRA completed on 10/01/02; PPP 9860



10.     What are the prospects for eradication? Given the epidemiology of the daylily rust
fungus and its ability to survive as a latent infection, eradication may be difficult once the
pathogen is introduced. Puccinia hemerocallidis is capable of surviving on daylily (and
possibly Hosta spp.) alone; no other host species is required for it to perennate. It spreads by
means of wind-blown or water-splashed urediospores and the movement of affected plants.
However, if infected plants are detected before spread is possible and there are no other hosts
in close vicinity, there is a chance that the fungus could be eradicated.
Spores of the rust fungus released from Patrinia spp. can infect daylily and possibly Hosta
spp. in the same way. Again if infected plants are detected before spread, the fungus could be
eradicated.

11. How would eradication be achieved? Eradication would be achieved by the
destruction of affected plants and by quarantining surrounding daylilies and other hosts,
which would need to be cut back and treated with systemic fungicides for an extended
period. Propiconazole and azoxystrobin are the fungicides recommended by Schubert and
Leahy (2001) and chlorothalonil and azoxystrobin by Buck and Williams-Woodward (2001).
In further research, the fungicides that consistently reduced rust development were the broad
spectrum protectants chlorothalonil and mancozeb, the sterol-inhibitor triadimefon and the
strobilurin azoxystrobin. Myclobutanil allowed the greatest amount of rust development
(Buck and Williams-Woodward, 2003). Azoxystrobulin has also been found to have curative
activity when applied up to seven days post-inoculation (Mueller et al., 2004). After the
treatment of unaffected plants, further inspections at an appropriate interval after application
would be needed to confirm eradication.

12. CSL action recommendations are to:
    (1) Carry out eradication procedures (as detailed above) on affected premises.
        Destruction of diseased plants and the treatment of associated plants (and possibly
        any other daylilies and alternate hosts that have been in close contact with any
        diseased plants) with an effective fungicide with curative activity.
    (2) Initiate surveys of daylily nurseries to determine if the rust is present in other
        locations in the UK.
    (3) Alert the EU/EPPO authorities to the danger of introducing daylily rust to the region
        on material imported from countries with the disease.
    (4) Investigate if there are risks posed by the trade of Patrinia and Hosta spp.




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PHSI Interception PRA for Puccinia hemerocallidis update prepared by David Jones, CSL; 17/02/05;
First PRA completed on 10/01/02; PPP 9860




13. References:

Anon. (2002). Daylily rust information page; http://www.ncf.ca/~ah748/rust.html.

Buck, J.W. and Williams-Woodward, J.L. (2001). In vitro fungicide sensitivity and optimum
germination temperature of the daylily rust pathogen, Puccinia hemerocallidis. Southern
Nursery Association Research Conference 46, 237-239.
(http://www.sna.org/research/01proceedings/Section0402.html)

Buck, J.W. and Williams-Woodward, J.L. (2003). The effect of fungicides on urediniospore
germination and disease development of daylily rust. Crop Protection 22, 135-140.

EPPO (2002). First report of Puccinia hemerocallidis in Australia. EPPO Reporting Service,
2002/038.

Hernández, J.R., Palm, M.E. and Castlebury, L.A. (2002). Puccinia hemerocallidis, cause of
daylily rust, a newly introduced disease in the Americas. Plant Disease 86, 1194-1198.

Hiratsuka, N. (1992) Puccinia hemerocallidis Thuemen 1880. In: The Rust Flora of Japan.
Tskuba Shuppankai Ibarki, pp. 710-711.

Mueller, D.S., Jeffers, S.N. and Buck, J.W. (2004). Effect of timing of fungicide applications
on development of rusts on daylily, geranium and sunflower. Plant Disease 88, 657-661.

Mueller, D.S., Williams-Woodward, J.L. and Buck, J.W. (2002). Effect of temperature on
the daylily rust pathogen. Phytopathology 92 (6 Supplement) S58.

Mueller, D.S., Williams-Woodward, J.L. and Buck, J.W. (2003). Resistance of daylily
cultivars to the daylily rust pathogen, Puccinia hemerocallidis. HortScience 38, 1137-1140.

Schubert , T and Leahy, R. (2001). Daylily Rust. Plant Pathology Pest Alert, Florida
Department of Agriculture and Consumer Services, Division of Plant Industry, Website;
http://doacs.state.fl.us/~pi/enpp/pathology/daylily-rust.html

Williams-Woodward, J.L. and Buck, J.W. (2001). Daylily rust caused by Puccinia
hemerocallidis: a new disease on daylily in the US. Southern Nursery Association Research
Conference 46, 234-236.
(http://www.sna.org/research/01proceedings/Section0402.html)

Yoshitaka, O. (2003). Does Puccinia hemerocallidis regularly host-alternate between
Hemerocallis and Patrinia plants in Japan? Journal of General Plant Pathology 69, 240-243.


Pest Risk Analyst:    David R. Jones
Editor and advice:    Claire Sansford
Location:             CSL
Date:                 17 February 2005
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