Stop rhizoctonia in sugarbeets
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For sugarbeet growers, Rhizoctonia is a common foe of their sugarbeet crops. Rhizoctonia is a fungus that favors hot temperatures and often overwinters in the soil and on plant tissue before beginning a new season of infection in the spring. Different types of Rhizoctonia called anastomosis groups (AGs) cause a number of diseases like crown and root rot, damping off and foliar blight. Rhizoctonia penetrates the beet through leaf petioles, the crown or the root and can cause up to a 50 percent loss in yield.
Prevention of Rhizoctonia is critical. Management practices begin in the fall with post-harvest field work and careful varietal selection. Oliver T. Neher, University of Idaho extension plant pathologist emphasized the importance of taking time after harvest to minimize inoculum for following years. “It is important to manage plant residues. Plan crop rotation to break up infection cycles and to reduce inoculum buildup. Minimize areas with standing water, hard pans or soil compaction, as they favor the development of Rhizoctonia.”
A proactive approach of planting tolerant varieties is especially important in fields with a chronic history of the disease. Corn and dry beans are alternate host crops for Rhizoctonia, which means that different crops should be considered for rotation with sugarbeets. With all crop rotations, it is important to maintain a clean field as Rhizoctonia has many alternate hosts in weed species, too.
“Growers should use all the tools available to maintain a healthy crop and prevent Rhizoctonia. Plant a tolerant variety and apply a seed treatment. Make a fungicide application and watch irrigation amounts and schedule,” Neher explained.
Choose wisely
Because Rhizoctonia is soil borne and has an effect on many crops, sugarbeets are at risk even before they are planted. Experts recommend planting tolerant seed varieties like Hilleshog® brand varieties to help the crop stand up to the disease.
“I strongly recommend that my growers use tolerant varieties. Planting tolerant or highly tolerant varieties is the most important tool we have. As part of an integrated pest management (IPM) program, the use of a tolerant variety is the first step that should be taken as they are effective in minimizing losses due to Rhizoctonia later in the season,” Neher said.
Pat Mahar, a sugarbeet grower in Cavalier, N.D., meticulously evaluates varieties for their disease performance and has found a Hilleshog brand variety that continues to perform year after year. “Personally, I like the 4094RR variety because of its extensive disease package. The 4094RR has seemed to be healthier than other varieties I have used in past years.”
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