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Abstract
Table beet (Beta vulgaris L.) ‘Ruby Queen’ seeds were either germinated in aerated water till radicle emergence or osmoconditioned (OC) in –1.2 MPa solutions of polyethylene glycol 6000 or MgSO4 for 7 days at 15°C. Seeds were sown in soil in growth chambers, infested with Pythium spp., and damping-off incidence was evaluated after 14 days. Disease incidence was reduced, compared to dry sown seeds, as a result of presowing treatments. High populations of bacteria (106–108 CFU/ml of solution) developed during the aerated soak, which protected seeds from Pythium damping-off. Seed leaching or osmoconditioning did not decrease susceptibility to damping-off in the absence of high seed bacterial populations. The fluid drilling gel was studied as a delivery system for chemical fungicides. Damping-off in dry-sown seed was reduced by incorporating thiram into a hydroxyethyl cellulose (Natrosol 250 HHW) gel. Gel alone had no effect on damping-off. In field studies, only slight improvements in stand were attributed to the incorporation of thiram in presowing treatments. Fungicide dressing of dry seed resulted in a large improvement in emergence. All presowing treatments had greater field emergence than dry-sown seeds in the absence of thiram, which was attributed to bacterial protection from damping-off.