Greg Shaner Department of Botany and Plant Pathology Purdue University Plant Pathology and Weed Science Research Relevant to Indiana’s Seed Industry Greg Shaner Department of Botany and Plant Pathology Purdue University Title

Seed industry issues Many disease and weed control issues are the same for farmers as for seed producers Higher value of seed crops Loss of yield or quality may have greater consequences Management options not economical for commodity producers may be economical for seed producers Title

Seed-related research Much of the research in Botany and Plant Pathology is relevant to the seed industry This summary will focus on programs that have a more direct bearing on production of seed Plant pathology Scott Abney, Larry Dunkle, Steve Goodwin, Guri Johal, Greg Shaner, Andreas Westphal Weed Science Bill Johnson, Tom Bauman, Kevin Gibson Title

Soybean sudden death syndrome Developed a method for evaluating root necrosis in the greenhouse (Westphal) Looking at combined effects of SCN and Fusarium solani f. sp. glycines on SDS (Westphal) Some evidence of soil suppressiveness of F. solani f. sp. glycines after 3 yr of continuous soybean (Westphal) Field evaluation of resistance to SDS (Abney) 10 yr ago, 90% of varieties were very susceptible Now, about half have some resistance Most highly susceptible varieties have been eliminated Title

Phytophthora rot Combining Rps1c or Rps1k with Rps3a or Rps8 (Abney) Evaluating some field isolates of Phytophthora sojae that overcome Rps8 (Abney) Title

Frogeye leaf spot Survey of isolates from throughout Indiana (Abney) None of these isolates overcomes Rcs3 Foliar fungicide trials (Shaner) Several treatments suppressed frogeye leaf spot Title

Soybean rust Extensive extension programs (Shaner and many others) Section 18 registrations of fungicides Foliar fungicide trials Evaluation of numerous products (Shaner) Farm-scale fungicide trials (Conley and Shaner) Sentinel plots Up-to-date advisories on USDA web site, and toll-free phone line Title

Gray leaf spot of corn Genetic variability in Cercospora zeae-maydis (Dunkle) Two distinct populations Resistance in corn expressed equally toward both A phytotoxin (cercosporin) is required for full development of lesions Title

Northern corn leaf blight Limited surveys indicate that races 0 and 1 predominate in Indiana Production of spores by Exserohilim turcicum involves a blue-light receptor (cryptochrome) To which races are the various genes effective? Title

Northern corn leaf spot (Johal) Basic studies on pathogenesis in Bipolaris zeicola and host resistance in corn Lesion mimics 50 are known Deciphering molecular basis may shed light on nature of disease resistance in corn Title

Dwarfing gene in corn (Johal) Brachytic2 (br2) Gene reduces length of lower internodes Cells are smaller, but more numerous (2-3x) This adds greatly to stalk strength brachy is Greek for short Title

Fungicides on seed corn (Shaner) Several effective products Initial treatment must be early in disease development Benefit depends on susceptibility of inbred and environment Title

Leaf blotch of wheat Several genes for resistance to Septoria tritici have been mapped (Goodwin) Stb1, Stb2, Stb4, Stb8 Most mapping is with microsatellites These are easy to work with--may lead to wider use in commercial breeding programs Helping to develop molecular markers for a linkage block that includes resistance to Stagonospora blotch, head blight, and stem rust (Goodwin) Evaluation of fungicides for efficacy against leaf blotch (Shaner) Title

Fusarium head blight Development of weather-based risk model Can be used to make decisions about fungicide use Evaluation of fungicides and application timing for control Discovery and characterization of new sources of resistance Title

Herbicide tolerance Popcorn (Bauman) Field corn (Bauman) Soybean (Johnson and Bauman) Includes studies of interactions of herbicides with fungicides and insecticides Title

Weed management (Johnson) Optimization and sustainability of weed management systems to reduce glyphosate-resistant weed problems Resistant weeds pose a serious threat to continued success of Roundup Ready technology Goal is to preserve efficacy of glyphosate resistance trait in soybean Re-evaluation of weed interference in corn grown with lower nitrogen rates Weed management systems in Roundup Ready, Bt corn Optimization required to offset higher seed costs Title

Vegetable weed management (Gibson) Has use of glyphosate reduced weed seedbank numbers? If so, this may lead to improved, cheaper weed management in vegetables that are rotated with field crops Title