How to Detect Stalk Rots

Stalk rots are an issue this growing season. Alison Robertson with Iowa State University’s Department of Plant Pathology, says she’s seen significant blighting of the leaves in the upper canopy predominantly from Goss’s wilt.  We normally see that disease west of the Missouri River but it has been moving east over the past few years.

Northern corn leaf blight, gray leaf spot and anthracnose top dieback have also been prevalent this season.  When significant leaf blight occurs in the upper canopy, the risk of stalk rots increases. Overcast conditions, such as we had throughout most of the grain filling period, also favor stalk rot development.

Since stalk rots reduce standability, fields in which greater than 10% of plants are affected by stalk rots, should be scheduled for an early harvest.  In the following video, Nick Benson shows how to identify stalk rot.

[youtube]http://www.youtube.com/watch?v=c064-2Pd-do[/youtube]

To help prioritize fields, Robertson offers these tips:

  • Target fields that have had significant foliar disease.
  • Target hybrids with low stalk rot and/or standability scores. Evaluate at least 100 plants per field (20 plants in 5 locations).
  • Use the “push test” or the “pinch test” to determine standability. If 10 to 15% of plants lodge or are rotted, schedule an early harvest.

Click here to read Robertson’s entire article on stalk rots and standability:  http://www.extension.iastate.edu/CropNews/2010/0913robertson.htm

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