L. pimpinellafolium x Bonner F1 and F2

[frogsleap farm]

My tomato beds are a Septoria hot spot. Despite heavy mulching, removing diseased debri, etc., I have Septoria problems every year. In 2007 I planted L. pimpinellifolium PI 422397, with reported tolerance to Septoria (Barksdale and Stoner, 1978; Poysa and Tu, 1993). It showed considerable tolerance in my garden, but was a real sprawler with typical small currant type fruit. In an adjacent row I had several plants of Bonner (very early, determinate type). This spring I planted ~100 OP seeds from 422397 and found 1 F1 plant. The F1 was erect, compact, very early flowering, with tasty small red cherry fruits. I segregated this tomato plant from the rest of the crowd and collected seed from a couple dozen F1 fruits. In late July I harvested the first F1 fruit, extracted seed and planted 27 F2 plants into a bed where my early tomatos had been decimated by Septoria. I left the infected debri on the soil surface. The F2 plants varied widely in phenotype; growth habit, plant size, flowering date, and Septoria tolerance. All F2 plants showed some Septoria infection, unfortunately I did not include a susceptible check. All but two were frosted before I could harvest fruit.

I'm willing to share some of the limited F2 seed with anyone interested in working on enhanced tolerance to Septoria leafspot. I'm going to try crosses to some L. hirsutum lines this summer as a follow up. I also have selections from various heirloom varieties that show some tolerance.