Breeding Early Blight Resistance for Tomato in Massachusetts

Abstract

Early blight disease on tomato, Lycopersicon esculentum, is caused by Alternaria solani, a fungus that primarily affects plants experiencing stress due to adverse growing conditions and heavy fruit loads. A. solani spreads rapidly under conditions of heavy dew and humid, damp weather which frequently occur during Massachusetts summers. Early blight appears as spots and cankers on tomato fruit, stems, and foliage. Host plant resistance to A. solani is exhibited by several lines of wild tomato relatives, including Lycopersicon hirsutum. Breeding efforts at North Carolina State Univ. to incorporate this resistance by making crosses to the wild tomatoes and then making backcrosses to L. esculentum have resulted in advanced breeding lines. These initial lines showed some resistance but have later maturity and lower yields than current commercial cultivars. Field evaluations of yield and early blight resistance were completed for 22 cultivars and advanced breeding lines in 1992 and 20 cultivars, advanced breeding lines, and new crosses in 1993. The new crosses in the 1993 trial were made between high yielding, susceptible lines and lower yielding, resistant lines as evaluated in 1992. Two of these crosses, NC-EBR1 × JETSTAR and 88B231 × SUNRISE, were selected to be used in single seed descent and bulk breeding programs. David L. Holm phone (413) 545-2917, e-mail dholm@hamp.hampshire.edu; Robert Bernatzky phone (413) 545-5222, e-mail rb@pssci.umass.edu