Crop rotations should be lengthened to 4-5 years where Rhizoctonia root rot has been a problem. Shortened rotations in recent years are the primary cause of the increased losses from Rhizoctonia root and crown rot. Shortening the rotation between sugarbeet crops leads to build-up of high soil populations of Rhizoctonia solani and other root pathogens. High pathogen populations increase the risk of root rot and render future control more difficult and costly. Monoculture of sugarbeet usually results in severe disease.
Severe loss can occur following beans, potatoes and alfalfa.
Significant losses from Rhizoctonia root rot have been experienced in fields that have had long sugarbeet rotations but were heavily cropped to beans. Hilling practices - The petioles and crown area are the most common entry points for R. solani , and hilling practices that push soil into contact with petioles or into the crowns are one of the most important factors contributing to disease problems. This pathogen resides in the soil, and such practices essentially inoculate these susceptible areas and should be avoided, especially where Rhizoctonia root and crown rot has been a problem. Figure 6 is an example of excess hilling in a field where sugarbeets had never previously been grown. Initial R. solani infection is evident in Figure 7 on petioles with the soil removed.