Biological Invasions

, Volume 11, Issue 1, pp 97–107 | Cite as

The impact of invasive fungi on agricultural ecosystems in the United States

Original Paper


Invasive fungi and other non-indigenous plant pathogens have had a significant effect on American agriculture for hundreds of years. At present crop loss due to invasive plant pathogens, especially fungi, is estimated at $21 billion per year in the United States, greater than the loss caused by non-indigenous insects. Plant pathogenic fungi are difficult to detect and identify. Thus knowledge of which fungi pose a threat is essential to prevent their entry by means others than inspection. In this paper, examples are presented of invasive fungi on agricultural commodities introduced into the United States. In all cases two factors have been crucial: first, the pathway through which these fungi have entered, and second, systematic knowledge to prevent and respond to the new invasive species. Historically important plant pathogens such as black stem rust of wheat still cause considerable damage while others such as late blight of potato appear to be having a resurgence. Known previously in Australia, then moving to Africa and South America, the virulent species of soybean rust appeared in the U.S. in 2004 but has not been as devastating as anticipated. Plant pathogenic fungi on specialty crops such as daylily, gladiola and chrysanthemum are threatened by rust fungi recently found in the U.S. apparently brought in on infected germplasm. A crisis in the export of U.S. wheat occurred in the late 1990’s when the molecular diagnostic test for Karnal bunt gave a false positive response to a closely related but previously unknown species. Many potentially dangerous plant pathogens of crop plants have not yet been introduced into the U.S. It is critical that meticulous surveillance be conducted as plant material enters the country as well as where crops are grown prior to shipment. In addition, the scientific infrastructure is needed to be able to respond quickly to new invasive fungi. This requires sound systematic knowledge of plant pathogenic fungi both in the U.S. and around the world and a cadre of systematic experts who can characterize invasive fungi.


Black stem rust Karnal bunt Non-indigenous pathogens Plant pathogens 


  1. Abbasi M, Goodwin SB, Scholler M (2005) Taxonomy, phylogeny, and distribution of Puccinia graminis, the black stem rust: new insights based on rDNA sequence data. Mycoscience 46:241–247CrossRefGoogle Scholar
  2. Baayen RP, Bonants PJM, Verkley G, Carroll GC, Van Der Aa HA, De Weerdt M, van Brouwershaven IR, Schutte GC, Maccheroni W Jr, de Blanco CG, Azevedo JL (2002) Nonpathogenic isolates of the citrus black spot fungus, Guignardia citricarpa, identified as a cosmopolitan endophyte of woody plants, G. mangiferae (Phyllosticta capitalensis). Phytopathology 92:464–477PubMedCrossRefGoogle Scholar
  3. Barnes CW, Szabo LJ, Johnson JL, Bowersox VC, Harlin KS (2006) Detection of Phakopsora pachyrhizi spores in rain using a real-time PCR assay. Phytopathology 96(6 suppl):S9Google Scholar
  4. Black BD, Padgett GB, Russin JS, Griffin JL, Snow JP, Gerggren GT Jr (1996) Potential weed hosts for Diaporthe phaseolorum var. caulivora, causal agent for soybean stem canker. Plant Dis 80:763–765Google Scholar
  5. Blomquist CL, Thomas SL, McKemy JM, Nolan PA, Luque-Williams M (2007) First report of Uromyces transversalis, causal agent of Gladiolus rust, in San Diego County, California. Plant Dis 91:1202CrossRefGoogle Scholar
  6. Bromfield KR (1984) Soybean Rust Monograph No. 11. American Phytopathological Society, St. Paul, Minnesota, p 63Google Scholar
  7. Campbell CL, Peterson PD, Griffith CS (1999) The formative years of plant pathology in the United States. APS Press, St Paul, MinnesotaGoogle Scholar
  8. Castlebury LA, Carris LM (1999) Tilletia walkeri, a new species on Lolium multiflorum and L perenne. Mycologia 91:121–131CrossRefGoogle Scholar
  9. Castlebury LA, Farr DF, Rossman AY (2001) Phylogenetic distinction of Phomopsis isolates from cucurbits. Inoculum 52:25Google Scholar
  10. Chatasiri S, Kitade O, Ono Y (2006) Phylogenetic relationships among Puccinia hemerocallidis, P. funkiae, and P. patriniae (Uredinales) inferred from ITS sequence data. Mycoscience 47:123–129CrossRefGoogle Scholar
  11. Cline ET, Farr DF (2006) Synopsis of fungi listed as regulated plant pests by the USDA Animal and Plant Health Inspection Service: Notes on nomenclature, disease, plant hosts, and geographic distribution. Online Plant Health Progr 05-05-06.Google Scholar
  12. Farr DF, Bills GF, Chamuris GP, Rossman AY (1989) Fungi on plants and plant products in the United States. American Phytopathological Society, St Paul, MinnesotaGoogle Scholar
  13. Farr DF, Rossman AY, Palm ME, McCray EB (2007) Fungal Databases, Systematic Botany & Mycology Laboratory, ARS, USDA. Retrieved from
  14. Farr DF, Castlebury LA, Rossman AY (2002) Morphological and molecular characterization of Phomopsis vaccinii and additional isolates of Phomopsis from blueberry and cranberry in the eastern United States. Mycologia 94:494–504CrossRefGoogle Scholar
  15. Fry WE, Goodwin SB (1997) Resurgence of the Irish potato famine fungus. Bioscience 47:363–371CrossRefGoogle Scholar
  16. Fry WE, Goodwin SB, Dyer AT, Matuszak JM, Drenth A, Tooley PW, Sujkowski LS, Koh YJ, Cohen BA, Spielman LJ, Deahl KL, Inglis DA, Sandlan KP (1993) Historical and recent migrations of Phytophthora infestans: chronology, pathways, and implications. Plant Dis 77:653–661Google Scholar
  17. Gómez-Alpizar L, Carbone I, Ristaino JB (2007) An Andean origin of Phytophthora infestans inferred from mitochondrial and nuclear gene genealogies. Proc Natl Acad Sci 104:3306–3311PubMedCrossRefGoogle Scholar
  18. Hawksworth D (2001) The magnitude of fungal diversity: the 1.5 million species estimate revisited. Mycol Res 105:1422–1432CrossRefGoogle Scholar
  19. Hawksworth DL, Rossman AY (1997) Where are all the undescribed fungi? Phytopathology 87:888–891PubMedCrossRefGoogle Scholar
  20. Hernandez JR, Palm ME, Castlebury LA (2002) Puccinia hemerocallidis, cause of daylily rust, a newly introduced disease in the Americas. Plant Dis 86:1194–1198CrossRefGoogle Scholar
  21. Hunter GC, Wingfield BD, Crous PW, Wingfield MJ (2006) A multi-gene phylogeny for species of Mycosphaerella occurring on Eucalyptus leaves. Stud Mycol 55:147–161PubMedCrossRefGoogle Scholar
  22. Ivors K, Garbelotto M, Vries IDE, Ruyter-Spira C, Hekkert B, Rosenzweig N, Bonants P (2006) Microsatellite markers identify three lineages of Phytophthora ramorum in US nurseries, yet single lineages in US forest and European nursery populations. Mol Ecol 15:1493–1505PubMedCrossRefGoogle Scholar
  23. Krupa S, Bowersox V, Claybrooke R, Barnes CW, Szabo L, Harlin K, Kurle J (2006) Introduction of Asian soybean rust urediniospores into the Midwestern United States–a case study. Plant Dis 90:1254–1259CrossRefGoogle Scholar
  24. Leonard KJ (2001) Stem rust–future enemy? In: Peterson PD (ed) Stem rust of wheat: from ancient enemy to modern foe. American Phytopathological Society, St Paul MinnesotaGoogle Scholar
  25. Levy L, Castlebury LA, Carris LM, Meyer RJ, Pimentel G (2001) Internal transcribed spacer sequence-based phylogeny and polymerase chain reaction-restriction fragment length polymorphism differentiation of Tilletia walkeri and T indica. Phytopathology 91:935–940PubMedCrossRefGoogle Scholar
  26. Li S, Bradley CA, Hartman GL, Pedersen WL (2001) First report of Phomopsis longicolla from velvetleaf causing stem lesions on inoculated soybean and velvetleaf plants. Plant Dis 85:1031CrossRefGoogle Scholar
  27. Licciardello G, Grasso FM, Cirvilleri G, Grimaldi V, Bella P, Catara V (2006) Identification and detection of Phoma tracheiphila, causal agent of citrus mal secco disease, by real-time polymerase chain reaction. Plant Dis 90:1523–1530CrossRefGoogle Scholar
  28. Manter DK, Reeser PW, Stone JK (2005) A climate-based model for predicting geographic variation in swiss needle cast severity in the Oregon coast range. Phytopathology 95:1256–1265PubMedCrossRefGoogle Scholar
  29. May KJ, Ristaino JB (2004) Identity of the mtDNA haplotype(s) of Phytophthora infestans in historical specimens from the Irish potato famine. Mycol Res 108:471–479PubMedCrossRefGoogle Scholar
  30. Meyer L, Sanders GM, Jacobs R, Korsten L (2006) A one-day sensitive method to detect and distinguish between the citrus black spot pathogen Guignardia citricarpa and the endophyte Guignardia mangiferae. Plant Dis 90:97–101CrossRefGoogle Scholar
  31. Ortiz-Garcia S, Gernandt DS, Stone JK, Johnston PR, Chapela IH, Salas-Lizana R, Alvarez-Buylla ER (2003) Phylogenetics of Lophodermium from pine. Mycologia 95:846–859CrossRefGoogle Scholar
  32. Palm ME (2001) Systematics and the impact of accidentally introduced fungi on agriculture in the United States of America. Bioscience 51:1–7CrossRefGoogle Scholar
  33. Palm ME, Rossman AY (2003) Invasion pathways of terrestrial plant-inhabiting fungi. In: Ruiz GM, Carlton JT (eds) Invasive species: vectors and management strategies. Island Press, Washington, DCGoogle Scholar
  34. Peterson PD (2001) The campaign to eradicate the common barberry in the United States. In: Peterson PD (ed) Stem rust of wheat: from ancient enemy to modern foe. American Phytopathological Society, St Paul MinnesotaGoogle Scholar
  35. Pimental D, Lach L, Zuniga R, Morrison D (2002) Environmental and economic costs associated with non-indigenous species in the United States. In: Pimentel D (ed) Biological invasions: economic and environmental costs of alien plant, animal and microbe species. CRC Press, Boca Raton, FloridaGoogle Scholar
  36. Pimentel D, Zuniga R, Morrison D (2005) Update on the environmental and economic costs associated with alien-invasive species in the U.S. Ecol Econ 52:273–288CrossRefGoogle Scholar
  37. Rodríguez-Alvarado G, Fernández-Pavía SP, Valenzuela-Vázquez M, Loya-Ramírez JG (2006) First report of gladiolus rust caused by Uromyces transversalis in Michoacán, México. Plant Dis 90:687CrossRefGoogle Scholar
  38. Roelfs AP (1982) Effects of barberry eradication on stem rust in the United States. Plant Dis 66:171–181Google Scholar
  39. Rossman AY, Palm ME (2006) Why are Phytophthora and other oomycota not true fungi? Outlooks Pest Manag 17:217–219CrossRefGoogle Scholar
  40. Rossman AY, Britton K, Luster D, Palm M, Royer MH, Sherald J (2006) Evaluating the threat posed by fungi on the APHIS list of regulated plant pests. Online. Pl. Health Progr. 05–05–06Google Scholar
  41. Schneider RW, Hollier CA, Whitam HK, Palm ME, Mckemy JM, Hernández JR, Levy L, DeVries-Paterson R (2005) First report of soybean rust caused by Phakospora pachyrhizi in the continental United States. Plant Dis 89:774CrossRefGoogle Scholar
  42. Schubert TS, Leahy RM, Davison DA, Silagyi AJ, Killgore EM (2007) Gladiolus rust caused by Uromyces transversalis makes first Nearctic appearance in Florida. Plant Dis 91:1202CrossRefGoogle Scholar
  43. Schumann GL (1991) Plant diseases: their biology and social impact. American Phytopathological Society, St Paul, MinnesotaGoogle Scholar
  44. Smith IM, McNamara DG, Scott PR, Harris KM (eds) (1992) Quarantine pests for Europe. CAB International with EPPOGoogle Scholar
  45. Smith OP, Peterson GL, Beck RJ, Schaad NW, Bonde MR (1996) Development of a PCR-based method for identification of Tilletia indica, causal agent of karnal bunt of wheat. Phytopathology 86:115–122CrossRefGoogle Scholar
  46. Stockstad E (2007) Deadly wheat fungus threatens world’s breadbaskets. Science 315:1786–1787CrossRefGoogle Scholar
  47. Takamatsu S (2004) Phylogeny and evolution of the powdery mildew fungi (Erysiphales, Ascomycota) inferred from nuclear ribosomal DNA sequences. Mycoscience 45:147–157CrossRefGoogle Scholar
  48. Ullstrup AJ (1972) The impact of the southern corn leaf blight epidemics of 1970–71. Annu Rev Phytopathol 10:37–50CrossRefGoogle Scholar
  49. Wise KA, Mueller DS, Buck JW (2004) Quarantines and ornamental rusts. APSnet Feature, St. PaulGoogle Scholar
  50. Ykema RE, Floyd JP, Palm ME, Peterson GL (1996) First report of karnal bunt of wheat in the United States. Plant Dis 80:1207Google Scholar

Copyright information

© US Government 2008

Authors and Affiliations

  1. 1.Systematic Mycology & Microbiology LaboratoryUSDA Agricultural Research ServiceBeltsvilleUSA

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