INTEGRATING FUNGICIDE SEED, IN-FURROW FUNGICIDES AND FUNGICIDE BAND APPLICATIONS FOR IMPROVED CONTROL OF RHIZOCTONIA CROWN AND ROOT ROT

摘要

Rhizoctonia crown and root rot occurs in every region that sugarbeets are grown. The disease is caused by a complex of Rhizoctonia solani 2-2 isg (interspecific group) IV and isg III B, with the isg III B become more predominant in areas where corn issignificant in rotations. Since the labeling of azoxystrobin (Quadris) in the mid 1990s growers have used banded and infurrow applications of this fungicide or products such as Headline, Gem or Proline. Efficacy of banded applications was greatly improved when researchers (Jacobsen, Khan) showed that applications must be made before soil temperatures at the 4 inch depth exceeded 70F and after soils at this depth were 60F, rather than a specific growth stage. However, timing for late planting or springswhen soils warm up quickly was a problem or where growers often had a small window for optimal timing. In our 15 years of Rhizoctonia work in MT, the period for optimal timing ranged from 3-17 days depending on the spring. Growers with large acreages frequently could not get optimal timing on all their acres. While Rhizoctonia resistant varieties are available, they frequently have lower yield potential, do not have the full component of other disease resistances such as Rhizomania, Curly Top, Aphanomyces, Fusarium Yellows, and Cercsopora needed by our growers and in our experience have also responded to properly timed fungicide applications with both increased yields and reduced disease severity.