Early Season Corn Uniformity and its effect on Yield, WBC and DON

  • Dec 11
    Laura Johnston
    Early Season Corn Uniformity and its effect on Yield, WBC and DON By Laura Johnston on December 11, 2018
    Categories: Corn Hybrid Selection, Corn Silage Management, Disease Control, Grain Corn, Silage Corn

    Early season corn crop uniformity can have long lasting effects. Each year we are struck with new challenges and often these challenges are amplified by what happened during planting. Yield, Western Bean Cutworm and vomitoxin are three major concerns that are affected by early season corn uniformity.

    Yield Loss

    Yield loss from stand uniformity has been looked at using the flag test. Peter Johnson’s work shows a 6-8% yield loss from plants emerging on day 2 and a 12-14% yield loss from plants emerging on day 3 (when compared to neighbouring plants that emerged on day 1). This is significant and can lead to many other issues in the fall.  In 2018 Maizex looked at deeper planting as a management technique to narrow the window of emergence.  Initial results look like this may be one tool we can use to tighten the emergence window and create more uniformity in our corn crop which in turn can increase yields and aid with other complications from uneven emergence.

    Figure 1. Flag test for uniformity of emergence.

    Flag test for uniformity of emergence

    Figure 2. Differences in ear size uniformity based on emergence.

    Differences in ear size uniformity based on emergence

     

    Damage from Western Bean Cutworm

    Western Bean Cutworm (WBC) is another challenge that can be worsened by uneven emergence. Yield loss due to infestation of one WBC larva per ear has been estimated to reach up to 15 bu/ac. In Ontario, WBC infestations cause injury to the ear and lead to secondary fungal infections and increased mycotoxin development in grain. Female WBC moths prefer to lay eggs in fields in the whorl to pre-tassel stage of corn. If there is no tassel in the whorl any eggs that hatch will die within a day or two. Variability in the growth stage caused by uneven emergence can cause pockets of WBC throughout the field. This opens up the pollination period even more. The variability in tassel timing can create a long window for WBC to lay their eggs and cause yield and quality issues.

    Figure 3. WBC feeding on late emerger.

    WBC feeding on late emerger

    Figure 4. Late emerger opens the window for WBC to lay eggs.

    Uneven Emergence and Ear Moulds

    During early season stand assessments this year variable emergence was present.  Following those runt plants into this fall you would find small ears with longer tighter husks.  This tight husk was the perfect environment for mould to grow. It has been evident this fall that runt ears/late emergers had a higher incidence of mould which has been contaminating grains samples with mycotoxins.

    Improvements with early season corn uniformity is a key factor in helping to address  yield reductions from variable emergence, western bean cutworm pressure and mold/DON in corn. Improvements in plant stands as well as plant to plant variability is key to helping manage these issues.

    Some ideas to help improve your early season corn uniformity are:

    Improve planter performance
    Plant deeper
    Slow down
    Wait for better soil conditions