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Breakdown of Resistance to Pseudomonas solanacearum in Tomato. Joseph P. Krausz, Graduate Research Assistant, Department of Plant Pathology, Cornell University, Ithaca, New York 14853; H. David Thurston, Professor, Department of Plant Pathology, Cornell University, Ithaca, New York 14853. Phytopathology 65:1272-1274. Accepted for publication 10 June 1975. DOI: 10.1094/Phyto-65-1272.

Elevated temperature (32 C) in environmental control chambers significantly increased severity of bacterial wilt in two tomato lines (Philippine 1169 and Hawaii 7580) resistant to Pseudomonas solanacearum. The level of resistance of a third line, Venus, to isolate K-60 was not significantly affected by temperature, but this line expressed no resistance to isolate LB-6 at all temperatures tested. Reduced light intensity (8,075 lux) did not reduce resistance to isolate LB-6 in line 1169 at 26.6 C but significantly decreased resistance at 29.4 C. Reduced photoperiod (9.5 and 10 hours) significantly decreased resistance of line 1169 to isolate LB-6 independent of temperature.