2017 ASHS Annual Conference

Managing foliar diseases including late blight (LB), early blight (EB), and Septoria leaf spot (SLS), is one of the biggest challenges facing organic tomato growers. New, resistant hybrid varieties are available, but growers often plant heirloom varieties because they are perceived to have superior flavor and they can save seed. Copper fungicides can provide fair control of these diseases, but these products are contact, not systemic, and must be applied often, which can negatively impact soil and water quality. The tomato organic management and improvement project (TOMI) brings together a multidisciplinary team of researchers to develop solutions to this challenge. Specific objectives of the project are to: 1) identify biofungicide and biostimulant combinations that can effectively control LB, EB and SLS, 2) develop new open-pollinated tomato varieties that are resistant to LB, EB and SLS and have excellent flavor, and 3) develop an improved understanding of factors that regulate induced systemic resistance (ISR), which refers to an enhanced defensive state in plants against pathogens mediated by beneficial microbes. Greenhouse and field trials are underway testing various biofungicide and biostimulant combinations in IN and NC. Preliminary results indicate the some products are as effective as copper products in controlling these diseases. Breeding populations are being screened annually alongside commercial controls in organic field trials at university research stations in IN, NC, OR and WI, and recombined during winter to strengthen desirable traits. Further screening of lines for potential release will be conducted in collaboration with growers in on-farm trials during 2017 and 2018. Finally, greenhouse and field trials are underway in IN to determine how tomato genotype, microbial species, and soil management regulate ISR expression. Preliminary results indicate that wild type and landrace genotypes are more responsive to ISR than a modern hybrid. Additional information about this project can be accessed at http://eorganic.info/tomi.