## Quarantine Pests Associat ed with Seed of Corn
Relatives in the Genera Echinochloa
, Eleusine
, Miscanthus
, Panicum
, Pennisetum
, Setaria , and Tripsacum

United States Department of Agriculture

Animal and Plant Health Inspection Service

November 2007

Agency Contact : Plant Epidemiology and Risk Analysis Laboratory
Center for Plant Health Science and Technology
Plant Protection and Quarantine 1730 Varsity Drive,
Suite 300 Raleigh, NC 27606Rev. Original July 18, 2008 2 Background
This selected list of plant pe sts occurring on the seed of "c orn relatives" was prepared by
the Center for Plant Health Science and Technology (CPHST) of the United States Department of Agriculture (USDA), Anim al and Plant Health Inspection Service (APHIS), Plant Protection and Quarantine (PPQ ) at the request of Alan Green, Director of Plant Health Programs (PHP). The corn relatives in question are Echinochloa spp. (barnyardgrass), Eleusine spp

. (finger millet), Miscanthus spp. (silver grass), Panicum spp. (millet), Pennisetum spp. (pearl millet), Setaria spp. (foxtail millet), and Tripsacum spp. (gamagrass). This request was for a pest risk assessment that confirms at least one seedborne quarantine pest is associated with each of the seven genera. The IPPC (2006) defines a quarantine pest as “a pest of potential economic importance to the area endangered thereby and not yet present there, or present but not widely distributed and being officially controlled.”

This request was for a science-based justif ication for the current prohibition on the importation of seeds of seven genera of corn re latives. This justification is needed for a proposed rule for consolidating the provisions of the 7 CFR 319 subparts that deal with plants for planting into the revised 7 CFR 319.37. PPQ prohib its the seeds of Echinochloa, Eleusine

, Panicum, Pennisetum , and Setaria from areas including Africa, Australia, Brazil, Bulgaria, Japan and adj acent islands, Korea, New Zealand, Oceania, the People’s Republic of China, Southeast Asia , Taiwan, and the former Soviet Union (Helms, 1987). Similarly, PPQ port-of -entry manuals prohibit seeds of Miscanthus and Tripsacum from “specific countries listed in 319.24 and 41.” Except for two species of

Pennisetum mentioned in 7 CFR 319.41, neither re gulation names these genera. Because existing regulations do not specifically proh ibit the seeds of these seven genera, PHP requested a risk-based jus tification for adding these pr ohibitions to 7 CFR 319.37. The expected products include a pest risk assessmen t that includes at le ast one quarantine pest for each regulated genus ( Echinochloa, Eleusine, Miscanthus, Panicum, Pennisetum, Setaria, and Tripsacum ) and a list of quarantine pests tr ansmitted by seeds of the genus.

This request is an important step in the re vision of 7 CFR 319.37, whic h is a high priority for PPQ. It meets an immediate need to review the current administrative prohibitions in the Code of Federal Regulations (CFR, 2007a, 2007b) for seeds of these genera.

Objective The objective is to provide an annotated list of quarantine pests th at are seedborne on the
corn relatives Echinochloa, Eleusine, Miscan thus, Panicum, Pennisetum, Setaria, and Tripsacum

.

Seedborne versus Seed-Transmitted Pathogens Seedborne pathogens are pathogens carried w ith, on, or in seeds. In contrast, seedtransmitted pathogens are not only seedborne, but also cause plant infection following seed propagation (Maude, 1996). Therefore, th e pathogens listed in Table 1 may or may
not cause direct infection of seed of the seve n evaluated genera. In addition, they may or may not propagate on or in the seed, or cause infection in the plan ts growing from the
seeds.Rev. Original November 16, 2007 3 Selected quarantine pest s on corn relatives Each of the seven corn relatives (Table 2) has two or more seedbor ne pests that are of quarantine significance. The IPPC (2006) defines a quarantine pe st as “a pest of potential economic importance to the area endangered thereby and not yet present there, or present but not widely distributed and being officially controlled.” Table 1. Selected seedborne pests listed by ge nera that are expected to be transmitted by seeds of corn relatives.

Pest Scientific Name of Pathogen Present in
U.S. Comments on the Pathway Distribution

Claviceps fusiformis Loveless [Fungi: Ascomycetes: Hypocreales: Clavicipitaceae] No (Wilson, 2000) Sclerotia can
contaminate seed lots (Wilson, 2000). Asia, Africa (Wilson, 2000)

Claviceps panicoidearum Tanda & Y. Harada [Fungi: Ascomycetes: Hypocreales: Clavicipitaceae] No (CABI, 2007) Sclerotia in other genera can contaminate
seed lots (Wilson, 2000). Japan only (CABI, 2007; JSCC, 2007; Tsukiboshi, 2001) Heterodera delvii Jairajpuri Khan, Setty & Govindu [Nematode: Heteroderidae] (Cereal cyst nematode) No (CABI, 2007) This cyst nematode is dispersed with soil debris and by plant
material contaminated by the cysts (SON, 2003). India (CABI, 2007; SON, 2003)

Heterodera sacchari Luc & Merni [Nematode: Heteroderidae] (Sugarcane cyst nematode) No (CABI, 2007;

SON, 2003) International transport may occur through soil or growing medium attached to plants or
seeds (SON, 2003). Africa, Asia, Europe ( Farr et al. , 2007 ,SON, 2003)

Peanut clump furovirus (PCV) [Virus] No (Brunt et al.

, 2006) Transmitted by seed (10%) in Setaria (Brunt et al. , 2006). Africa, India (Brunt et al.

, 2006)

Peronosclerospora philippinensis (W. Weston) C. G. Shaw Syn: Sclerospora philippinensis W. Weston [Chromista: Oomycetes: Sclerosporales: Sclerosporaceae ] No (CABI, 2007) Seedborne transmission may occur in corn (CABI, 2007). Asia, Africa CABI, 2007)

Peronosclerospora sacchari (T. Miyake) Shirai & Hara 1927 [Chromista: Oomycetes: Sclerosporales: Sclerosporaceae ] No ( Farr et al.

, 2007, PNKTO, 1986) Disseminated as a
contaminant (PNKTO, 1986). Asia, Africa,
Central America,
Oceania South
America (including Brazil) , (CABI, 2007; SON, 2003)Rev. Original July 18, 20084Table 2.Selected quarantine pests2on corn relatives3.ClavicepsfusiformisLoveless[Fungus]ClavicepspanicoidearumTanda &Y. Harada[Fungus]HeteroderadelviiKhan,Setty &Govindu[Nematode]HeteroderasacchariLuc & Merni[Nematode]Peanut clumpfurovirus[Virus]PeronosclerosporaphilippinensisC. G. Shaw[Fungus]Peronosclerosporasacchari(T. Miyake) Shirai& Hara[Fungus]Echinochloaspp.SON, 2003Wilson, 2000Eleusinespp.SON, 2003Bruntet al.,2006Miscanthusspp.CABI, 2007;JSCC, 2007;Tsukiboshi,2001PNKTO, 1986,Farret al., 2007Panicumspp.Wilson,2000Wilson, 2000Pennisetumspp.Wilson,2000Wilson,2000Wilson, 2000Setariaspp.Wilson,2000Wilson, 2000Tripsacumspp.Wilson, 2000 PNKTO, 1986,Farret al., 20072The IPPC (2006) defines a quarantine pest as “a pest of potential economic importance to the area endangered thereby and not yet present there, orpresent but not widely distributed and being officially controlled.”3"Corn relatives”, for the purpose of this document, areEchinochloaspp. (barnyardgrass),Eleusinespp.(finger millet),Miscanthusspp. (silver grass),Panicumspp. (millet),Pennisetumspp. (pearl millet),Setariaspp. (foxtail millet), andTripsacumspp. (gamagrass).

November 13, 2007 4 DraftRev. Original November 16, 2007 5 Information available on quarantine pathogens previously reported (Reynolds, 1987) as associated with seeds of corn relatives (Table 3) wa s ambiguous or insufficient for this evaluation. Therefore, the pathogens in Table 3 were not analyzed further."

Table 3. Pathogens listed by Reynolds, 1987.

Pest Scientific Name of Pathogen Present in
U.S. Quarantine
Pest Comments
on the Pathway Distribution References

Brachysporium senegalense NI 1 NI NI NI NI

Colletotrichum
eleusinis NI NI NI NI NI

Curvularia oryzae NI NI NI NI NI
Drechslera pluriseptata NI NI NI NI Khetarpal,
1984

Pseudomonas
eleusineae NI NI Bio-control
agent NI Sitther,
1996 Pyricularia pennisetum NI NI NI NI NI

Pyricularia setariae Yes (CABI, 2007) No Bio-control
agent (CABI, 2007) China, India, Japan, Malaysia, Sri Lanka, Africa (CABI, 2007) Sorosporium cryptum NI NI NI NI NI Sorosporium
kinshasaensis NI NI NI NI NI

Sphacelotheca mcalpineae NI NI NI NI NI

Tilletia ayresii No (Cline, 2007) Yes NI Africa (Cline, 2007) NI

Tilletia eleusines NI NI NI NI NI
Tilletia setariae NI NI NI NI NI Tolyposporium
setariicolum NI NI NI NI NI

Ustilago confuse NI NI NI NI NI Ustilago dactyloctaenii NI NI NI NI NI

Ustilago dactylocteniophila NI NI NI NI NI

Ustilago eleusinis NI NI NI Unconfirmed (CABI, 2007) NI

Ustilago idonea NI NI NI NI NI

= Ustilago panicigracile (Cline, 2007) Sporisorium neglectum (Niessl) Vánky 1985 NI NI NI Widespread (Cline, 2007) NI

Ustilago paradoxa NI NI NI NI NI Ustilago pertusa NI NI NI NI NI

1 Ambiguous or no host information available (CABI, 2007; Cline, 2007).Rev. Original November 16, 2007 6 Summary Peronosclerospora philippinensis , a fungal pathogen listed in the Agricultural Select Agent in the Agricultural Bioterrorism Pr otection Act of 2002 (CFR , 2005), is seedborne

on Echinochloa spp., Panicum spp., Pennisetum spp., Setaria spp., and Tripsacum spp. Peronosclerospora philippinensis is a destructive disease of corn in tropical Asia that poses a severe threat to plant health and plant products in th e United States. Furthermore, each of the corn relatives infected by P. philippinensis is also a seedborne pathway for other fungal, viral, or nematode quara ntine pests (Table 2). The nematode Heterodera
delvii and the peanut clump furovirus are seedborne on Eleusine spp. Heterodera delvii may suppress corn yields (SON, 2003). Peanut clump furovirus causes severe yield loses in peanut crops, and in several legume and cereal crops (Wesley, 1996). The fungal pathogens Claviceps panicoidearum and Peronosclerospora sacchari follow the pathway

on Miscanthus spp. Claviceps panicoidearum produces sclerotia in the plant head that are toxic to livestock (Tsukibos hi, 2001); it has a wide ra nge that includes wheat, rye, timothy, and fescue. Peronosclerospora sacchari is severe on sugarcane and corn in Australia and Taiwan (PNKTO, 1986).

None of the aforementioned pest s is present in the United Stat es, but they are likely to enter the country via seeds of co rn relatives. All pests in Table 2 are present in one or more of the prohibited areas, including Africa, Australia, Brazil, Bulgaria, Japan and adjacent islands, Korea, New Zealand, O ceania, the People’s Republic of China, Southeast Asia, Taiwan, and the former Soviet Union (Brunt et al. , 2006; CABI, 2007; Helms, 1987; SON, 2003; Tsukiboshi, 2001; Wilson, 2000).

Recommendation
The current APHIS administrativ e prohibitions for seeds of Echinochloa spp. (barnyardgrass), Eleusine spp

. (finger millet), Miscanthus spp. (silver grass), Panicum spp. (millet), Pennisetum spp. (pearl millet), Setaria spp. (foxtail millet), and Tripsacum spp. (gamagrass) are justifie d and should be codified in the plants for planting regulations.

A qualitative pest risk analysis using the methodology and rating criteria in Guidelines for Pathway-Initiated Pest Risk Assessment, Version 5.02 (USDA, 2000) is suggested for the following quarantine pests: Claviceps fusiformis (fungus), C

. panicoidearum (fungus), Heterodera delvii (nematode) , H. sacchari (nematode), peanut clump furovirus (virus), Peronosclerospora philippinensis (Chromista), and P. sacchari (Chromista), to potentially identify other s eed hosts requiring regulation.

Author L. G. Brown, Plant Pathologist/Senior Risk Analyst, USDA, APHIS, PPQ, CPHST

Reviewers S. C. Redlin, Plant Pathologist/Senior Risk Analyst, USDA, APHIS, PPQ, CPHST R. A. Schall, Plant Pathologist/Risk Analyst, USDA, APHIS, PPQ, CPHSTRev. Original November 16, 2007 7 Literature Cited Brunt, A. A., K. Crabtree, M. J. Dallwitz, A. J. Gibbs, L. Watson, E. J. Zurcher, and (eds). 2006. Plant Viruses Online: Desc riptions and Lists from the VIDE
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