EVALUATION OF SEED TREATMENTS ON SHRUNKEN-2 SWEET CORN

Sweet corn seed treatments were evaluated at Vincennes, Indiana and Urbana, Illinois in 1992 and 1993. In 1992, the soil was cool and moist at both locations, and the most prevalent fungi 5 and 10 days after planting (DAP) included Pythium ultimum, Rhizopus stolonifer, R. arrhizus, and Trichoderma spp. P. ultimum, an important pathogen of sh2 sweet corn, was isolated more frequently 5 DAP than 10 DAP. In 1993, P. ultimum was not isolated from seed collected at Vincennes as commonly as were Trichoderma spp., Fusarium moniliforme, and Penicillium oxalicum. Treatments which enhanced stand establishment had the broadest range of activity. Standard fungicide + polymer + priming was the only treatment of 20 for which stands were significantly greater than the untreated, primed control in all four trials. Stands for the standard fungicide, primed metalaxyl, and primed metalaxyl/captan treatments were greater than the primed, untreated control in three of four trials. Solid matrix priming of seed increased stands when added to relatively ineffective fungicide treatments, but priming gave little additional stand improvement when fungicides were effective. Priming improved plant height much more than plant stands. Multicomponent seed treatments including protectant fungicides such as captan/thiram, a broad spectrum systemic with activity against Fusarium and Penicillium spp., a compound effective against Pythium spp., some form of priming, and inert polymer coatings may not be necessary in all environments but may enhance stand and growth of sh2 seed in certain adverse environments. Unless adverse environments can be predicted, multicomponent seed treatments provide the best protection against poor stands and seedling diseases of sh2 corn.