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Biological seed treatments provides an alternative to chemical seed treatments or may also be used in combination with chemicals for effective control of plant pathogens. Seed treatment technologies are an important component of pest management, especially for effective biological control. Several seed treatments have been developed and evaluated to increase efficacy of the bioprotectant, Trichoderma harzianum, including 1) suspending the bioprotectant in a binder for a slurry application, 2) use of film coating technology, termed liquid coating, 3) combination of physiological treatments such as priming with the biological and 4) a dry planter box formulation. A laboratory bioassay consisting of sowing cucumber seeds in Pythium or other pathogen infested soil has shown that seed treatment technologies can enhance the efficacy of the bioprotectant. Field research has been conducted over four growing seasons on standard sugary and sh2 sweet corn. In general, emergence from seeds treated with Trichoderma by the described methods was comparable to seeds treated with chemical pesticides. Furthermore, plant growth was enhanced in several field studies.
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.