Eggplant (Solanum melongena) and other Solanum spp. are aecial hosts for Puccinia substriata var. indica, the rust pathogen of pearl millet (Pennisetum glaucum) (2). Although long suspected to be important in epidemic initiation (1), natural infection of eggplant has never been documented in the United States. All previous observations have been the result of deliberate inoculations. Eggplant (cv. Santana) seedlings with sporulating aecia were identified in the inventory of a vegetable transplant producer near Ty Ty, GA, on 22 April 1997. Flats of seedlings were being grown in a greenhouse with adjustable sides for creating an open-air environment for temperature control. Disease incidence was approximately 1.5% in the lot of 10,000 seedlings. Lesions were found most frequently on the first true leaf or less frequently on cotyledons. Aeciospores from 15 arbitrarily selected leaves were used to inoculate pearl millet seedlings in the greenhouse. Each leaf was used to inoculate pearl millet cultivars with no known resistance, and with the Rr1 resistance gene. Infection was obtained on all cultivars with no resistance genes, verifying pathogen identification. Fourteen isolates infected pearl millet with Rr1, revealing that virulence to Rr1 was common in this sample. The nearest point source of exposed pearl millet debris that could serve as a source of basidiospores was located approximately 9.7 km away from the eggplant.
References: (1) H. D. Wells. Plant Dis. Rep. 62:469, 1978. (2) J. P. Wilson et al. Plant Dis. 80:806, 1996.
