A field study was conducted in 2002 at St.Thomas (Pembina Co., North Dakota) for managing the sugarbeet root maggot (SBRM), Tetanops myopaeformis (R�der), using granular (planting time) and liquid (postemergence) formulations of the strain MA-1200 (a highly virulent strain of M. anisopliae) with two cereal cover crops- oat, Avena sativa L., and rye, Secale cereale L. A split-split-plot field design was used with oat and rye cover crops as the main treatments, seeding rates (0, 1.5, and 3.0 oat-bushel equivalents [OBE] per acre) as secondary-level treatments, and MA-1200 formulations compared to terbufos 15G and an untreated control as tertiary-level treatments. A 0 to 9 damage rating (DR) scale was used to evaluate root injury (0=no visible feeding injury, 9=75% of root surface scarred). Our results from 2002 indicate that, under the moderate root maggot pressure (DR=6.08 in untreated check), rye cover without any treatment provided significantly better root protection than oat (DR=5.30 and 6.24, respectively). Overall, the granular MA-1200 treatment provided significantly better root maggot control when integrated with the rye cover (DR=4.67) than when combined with oat (DR=5.72). However, liquid MA-1200 integrated with rye and oat cover crops were not significantly different from each other (DR=5.58 and 5.01, respectively). Rye provided better ground cover than oat at the high seeding rate, which probably intercepted much of the ultraviolet radiation and protected MA-1200 spores in soil. The experiment was repeated at a second location in 2003 and a summary of the investigation will be presented.
Species 1: Diptera Otitidae Tetanops myopaeformis (sugarbeet root maggot)
Keywords: cover crops
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