Erwin and Ribeiro (Erwin and Ribeiro 1996) list 89 host species of P. infestans, but more than 25% of these were based only on artificial inoculations.  Some of the hosts mentioned have only been reported once and others may have been attacked by morphologically similar species, which have only recently been identified.  Species of both Ipomoea and Mirabilis are listed as hosts by Erwin and Ribeiro (Erwin and Ribeiro 1996), but disease on these may have been caused by P. ipomoea (Flier, Grünwald et al. 2002) and P. mirabilis (Goodwin, Legard et al. 1999), respectively.  Although, P. infestans is probably an aggressive pathogen of all tuber-bearing genotypes in the genus Solanum, the very large number of tuber-bearing Solanum species exaggerates the host range, as many of these species classifications could be the result of overzealous splitting by plant taxonomists (Spooner, van den Berg et al. 2003).

 Of the non-tuber bearing Solanum hosts, tomato, S. lycopersicum, is the most important economically.  Other domesticated Solanum species are also hosts of P. infestans, including pear melon (S. muricatum) (Turkensteen 1978), tree tomato (S. betaceum) (Oliva, Erselius et al. 2002), and naranjilla (S. quitoense) (Adler, Erselius et al. 2003).  Eggplant has also been reported as an occasional host of P. infestans (Hooker 1981), but lack of disease reports in this very cosmopolitan crop puts its host status in doubt.  P. infestans is undoubtedly also a pathogen of the wild Solanum species closely related to tomato (Abad, Abad et al. 1995), but there are few references to field epidemics on these.  A recent study in South America listed 6 wild non-tuber bearing Solanum species and one species complex attacked in nature by P. infestans.  However, some isolates of the pathogen associated with certain hosts are so unusual that they may be new species of Phytophthora (Adler, Erselius et al. 2003).  A recent study in Canada showed that the nightshades, S. dulcamara and S. sarrachoides were infected while black nightshade, S. nigrum, was not (Platt 1999).  In Europe, natural infections were found on S. nigrum, S. dulcamara and S.  sisymbriifolium  (Flier, van der Bosch et al. 2003).  One study in California found that 11 Solanum species were infected by inoculation in a greenhouse, however, only one of these, S. sarrachodes, was infected naturally in the field (Vartanian and Endo 1985).

There have also been references to infection in Solanaceous plants outside the genus Solanum.  Nolana speices are apparently attacked on the coast of Peru during the wet winter season (Turkensteen 1978; Abad, Abad et al. 1995).  Datura species have been reported as hosts of P. infestans (Sunita and Sen 1997), but it is not clear if infections occur naturally in the field.  Extensive sampling in Ecuador, were Datura spp. are common weeds has not produced any indication that this genus is a host (Adler, Erselius et al. 2003).  Brugmansia sanguinea is also attacked by P. infestans in South America, but lesions have only been found on flower petals (Adler, Erselius et al. 2003).  P. infestans also attacks Petunia (Platt 1999).

Africa is center of diversity of Solanum and several species from that continent have been cited as hosts of P. infestans.  Kori (Kori 1972) reported that S. indicum, S. incanum and S. aculosturm were all infected in the field.  Natural infection in S. incanum and S. indicum were confirmed by Nattrass and Ryan (Nattrass and Ryan 1951), as well as infection in one unidentified species of Solanum. The cultivated crop, garden huckleberry (S. scabrum) was reported as a host of P. infestans in Cameroon (Nkengaka 2000).

Literature Cited

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Adler, N. E., L. J. Erselius, et al. (2003). "Genetic diversity of Phytophthora infestans sensu lato in Ecuador provides new insight into the origin of this important plant pathogen." Phytopathology in press.

Erwin, D. C. and O. K. Ribeiro (1996). Phytophthora infestans (Mont.) de Bary (1876). Phytophthora Diseases Worldwide. D. C. Erwin and O. K. Ribeiro. St. Paul, Minnesota, APS Press: 346-353.

Flier, W. G., N. J. Grünwald, et al. (2002). "Phytophthora ipomoeae sp. nov., a new homothallic species causing leaf blight on Ipomoea longipendunculata in the Toluca Valley of central Mexico." Mycological Research 106: 848-856.

Flier, W. G., G. B. M. van der Bosch, et al. (2003). "Epidemiological importance of Solanum sisymbriifolium, S. nigrum and S. dulcamara as alternative hosts for Phytophthora infestans." Plant Pathology In press.

Goodwin, S. B., D. E. Legard, et al. (1999). "Gene flow analysis of molecular markers confirms that Phytophthora mirabilis and P. infestans are separate species." Mycologia 91(5): 796-810.

Hooker, W. J., Ed. (1981). Compendium of Potato Diseases. St. Paul, MN, APS Press.

Kori, J. (1972). A survey of races of Phytophthora infestans in East Africa and the development of late blight resistant varieties. Kampala, Uganda, Makerere University: 72.

Nattrass, R. M. and M. Ryan (1951). "New hosts of Phytophthora infestans in  Kenya." Nature 168(4263): 85 -86.

Nkengaka, P. (2000). Inventory and assessment of major diseases of indigenous vegetables in Fouimbot. Dschang, University of Dschang.

Oliva, R. F., L. J. Erselius, et al. (2002). "Potential of sexual reproduction among host-adapted populations of Phytophthora infestans sensu lato in Ecuador." Plant pathology 51: 710-719.

Platt, H. W. (1999). "Response of solanaceous cultivated plants and weed species to inoculation with A1 or A2 mating type strains of Phytophthora infestans." Canadian Journal of Plant Pathology 21(3): 301-307.

Spooner, D. M., R. G. van den Berg, et al. (2003). "Species concepts and reduction of species in wild and cultivated potatoes (Solanum section Petota)." Acta Horticulturae (in press).

Sunita, S. and S. Sen (1997). "Host range of Phytophthora infestans, the incitant of leaf blight of Kangaroo apple." Journal of Mycology and Plant Pathology 27(2).

Turkensteen, L. J. (1978). "Phytophthora infestans: three new hosts and a specialized form causing a foliar blight of Solanum muricatum in Peru." Plant Disease Reporter 62(9): 829.

Vartanian, V. G. and R. M. Endo (1985). "Overwintering hosts, compatibility types, and races of Phytophthora infestans on tomato in southern California." Plant Disease 69: 516-519.