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

Title 2 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 3 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 4 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 5 Phytophthora rot  Combining Rps1c or Rps1k with Rps3a or Rps8 (Abney)  Evaluating some field isolates of Phytophthora sojae that overcome Rps8 (Abney)

Title 6 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 7 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 8 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 9 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)

Title 10 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 11 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

Title 12 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 13 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 14 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 15 Herbicide tolerance  Popcorn (Bauman)  Field corn (Bauman)  Soybean (Johnson and Bauman) Includes studies of interactions of herbicides with fungicides and insecticides

Title 16 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 17 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