A field study was conducted in 2002 at St.Thomas (Pembina Co., North Dakota) for managing the sugarbeet root maggot (SBRM), Tetanops myopaeformis (Röder), 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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