Infection Potential of Hairy Nightshade (Solanum sarrachoides)by Phytophthora infestans and Late Blight Implications of the Alternate Host
Olanya. O. M Plant. A. B Larkin. R. P Honeycutt. C. W
Journal of Phytopathology ; 2009 [Vol.157] Pages:427-437
Abstract
Infection of hairy nightshade (Solanum sarrachoides Sendt.) by Phytophthora infestans has been reported. However, the epidemiological significance of hairy nightshade to potato late blight is not well known. Disease development and infection rates of P. infestans were quantified on hairy nightshade relative to tomato (cv. Brandywine) and potato (cv. Shepody) hosts to evaluate infection potential at 14, 18, 22 and 26°C and 72, 82, 87, and 92% relative humidity (RH). The susceptibility of hairy nightshade to inoculum levels, weed ontogeny, and sporangia production potential were also investigated. Late blight development varied among hairy nightshade, tomato and potato hosts. Pathogen infection rates ranged from 0.0325 to 0.4674 gompits/day (unit for quantifying infection rates), and were significantly (P < 0.05) greater on potato and tomato than on hairy nightshade. Late blight severity was variably affected by RH. Disease levels on hairy nightshade varied with inoculum load; and ranged from 9 to 26% and 26 to 37% at low (5 × 103) and high (25 × 103) sporangia concentrations, respectively. Late blight was recorded irrespective of hairy nightshade ontogeny, and was significantly greater on 8–10 than 4–6-week-old plants. These results indicate that pathogen, environmental and host factors affect late blight development on hairy nightshade.
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