Rhizoctonia root and crown rot, caused by Rhizoctonia solani AG-2-2, is becoming more severe in sugarbeet (Beta vulgaris L. ssp. vulgaris) fields in North Dakota and Minnesota, USA. Azoxystrobin controls Rhizoctonia solani in artificially inoculated trials when applied just prior to infection. However, it is difficult to know exactly when infection occurs in the field. Field research was conducted during 2003-05 in North Dakota and Minnesota (2004 only) with sugarbeet cv. Beta 3800 to determine the soil temperature at which azoxystrobin should be applied to control Rhizoctonia solani. Azoxystrobin was applied at 0.67 L ha-1 in 187 liter of solution… Login to continue