Crop & Pest Report


| Share

Lookout for Common Root Diseases of Sugarbeet (06/06/19)

The most common root diseases of sugarbeet are Pythium, Rhizoctonia and Aphanomyces.

The most common root diseases of sugarbeet are Pythium, Rhizoctonia and Aphanomyces.  In warm and wet conditions at planting or soon after planting, damping-off – which is more or less seedlings being infected at or just below the soil-line resulting in the seedlings toppling over and die – can be common. In most growing areas, damping-off has not been an issue for our growers to date. In southern Minnesota where it is wetter, growers should be on the lookout for damping-off. As the plants get older, they can be affected by Rhizoctonia and Aphanomyces root rot.  For diseases such as Rhizoctonia root rot, it will mean that a post application of fungicides, such as Quadris® or Priaxor®, will become more critical at the 4 to 8-leaf stage sugarbeet, especially if we do get wet and warm soils. Typically, we get best protection from Rhizoctonia root rot when the fungicide is applied just before a ¼ inch to ½ inch rainfall.  It is always wise to use an integrated system of tolerant varieties, fungicidal seed treatments, and fungicide post application in a timely manner.


Managing Aphanomyces

Tachigaren® treated seeds will control Aphanomyces damping-off.  In addition, the use of precipitated calcium carbonate, or waste lime from the sugar factories, also helps to control early season Aphanomyces damping-off and later season root rot.  Aphanomyces can be damaging when there is abundant free moisture and warm soils, especially to beets less than four weeks old. In fields with a history of Aphanomyces, growers should have a long-term plan that should include planting resistant varieties, using Tachigaren® seed treatment, and applying and incorporating waste lime (5 to 8 tons/acre) at least in the fall prior to planting sugarbeet.


Impact of corn and soybean in the sugarbeet rotation on diseases

In many areas, corn and soybean are grown in rotation with sugarbeet. Rhizoctonia solani, the pathogen that causes Rhizoctonia damping-off and root rot also infects soybean and survives on corn root. As such, growers should try to avoid planting corn and soybean just prior to sugarbeet. If possible, plant a wheat or barley crop just before sugarbeet. If a grower must have corn and bean in the rotation, it may be better to plant sugarbeet following corn than beans so as to have fewer issues with Rhizoctonia. Use fungicide seed treatments to help reduce the population of the pathogen; plant early when the soils are cool and the pathogen is not at an infective stage; include a Rhizoctonia tolerant variety; improve drainage of fields; finally, use timely applications of effective fungicides.


Mohamed Khan

Extension Sugarbeet Specialist

NDSU & U of MN


This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

USDA logo

Creative Commons License
Feel free to use and share this content, but please do so under the conditions of our Creative Commons license and our Rules for Use. Thanks.