GERMINATION OF SH2 SWEET CORN FOLLOWING SEED DISINFESTATION, SOLID-MATRIX PRIMING, AND MICROBIAL SEED TREATMENT

Sweet corn (Zea mays L.) cultivars carrying the sh2 mutation show poor seed vigor under stressful field conditions, requiring higher seeding rates to ensure stand establishment. The effects of sodium hypochlori te seed disinfestation, solid matrix priming (SMP), and seed-coating w ith Gliocladium virens Miller, Giddens & Foster to enhance emergence o f sh2 sweet corn in controlled-environment cold stress tests and field trials were investigated. In combination with a chemical fungicide se ed treatment (captan, thiram, imazalil, and metalaxyl), SMP significan tly improved the percentage and rate of seedling emergence of 'Excel' and 'Supersweet Jubilee' in a cold stress test (in soil for 7 days at 10C, then 15C until emergence) but was inconsistent under field condit ions, improving emergence in only one of four field trials. Sodium hyp ochlorite disinfestation was ineffective. Compared to a film-coated co ntrol, coating seeds with G. virens strain G-6 was highly effective in increasing emergence in two of three cultivars tested in cold stress tests in two soils, while strain G-4 was generally ineffective. In fie ld trials, G-6 treatment significantly increased emergence over that o f nontreated seed but was inferior to conventional fungicide treatment and conferred no additional benefit in combination with fungicide tre atment. Overall, no seed treatment evaluated was an economically viabl e alternative for or supplement to chemical fungicide treatment. Chemi cal names used: richloromethylthio-4-cyclohexene-1,2-dicarboximide (ca ptan); tetramethyl-thiuram disulfide (thiram); chlorophenyl)-2-(2-prop enyloxy)ethyl]-1H-imidazole (imazalil); N-(2,6-dimethylphenyl)-N-(meth oxyacetyl)-alanine methyl ester (metalaxyl).