Extension Ag Update
October 2008
Articles Research Resources Internet Links Ag Facts Education

Scouting for Stalk Rot

Ellen Phillips, Extension Educator, Countryside Extension Center, ephillps@illinois.edu, 708-352-0109

Stalk rot fungi have different symptoms, but they affect the corn plant in the same way.  Stalk strength decreases which increases lodging,   grain fill is reduced and dry down speeds up.   Lodging can cause more yield loss than the effects of the fungal disease. Stalk rots can affect nutrient movement in the plant by blocking pathways leading to lower yield.  Stress is one factor influencing the amount of stalk rot development with the degree of injury increasing with higher levels of stress.

The most common types of stalk rot are Anthracnose, Gibberella, Fusarium, Diplodia and Pythium.   Detailed information on these diseases can be found at Field Crop Diseases website cropdisease.cropsci.uiuc.edu  and in the publication “Corn Stalk Rots” www.ag.uiuc.edu/~vista/abstracts/aCORN.HTML

Steps to Scouting for Stalk Rot
The amount and distribution of stalk rot diseases varies year to year.  Most years it is possible to find a low level of rot in most fields.   Here are two ways to test for stalk rot.
The Push Test

  • Randomly look at 100 plants in the field.
  • Push the top part of the stalk.  Does the plant lodge?
  • If 10 –15% of plants lodged then consider harvesting this field first.

 The Pinch or Squeeze Test:

  • Randomly look at  100 plants
  • Pinch or squeeze the stalk above the brace roots
  • If 10 –15% of plants lodged then consider harvesting this field first

The best way to control diseases in the field is to plant crops that have disease resistance built into its genetics.  To find out more about specific varieties check out the Crop Science Department Variety Field Trial results webpage http://vt.cropsci.uiuc.edu/.