Corn Journal
  • Corn Journal
  • Author
  • Stalk Rot Booklet
  • Seed Testing
  • Corn Genetics
  • Pathology
  • Sponsors
  • Contact
"You can see a lot by just looking"-Yogi Berra

leaf disease dynamics

8/31/2021

 
​Every growing season, every field, every hybrid has some difference in dynamics affecting corn leaf diseases. The primary process, however, remains the same. Fertilization of the of the embryos in the ear induces physiological changes in the leaves as movement of carbohydrates emphasizes the developing kernels.
 
Annual plants such as maize are genetically programmed to salvage nutrients from leaves after pollination, resulting in senescence of the leaves.  One study (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0115617) maintained that it begins in the ear leaf of corn as early as 14 days after pollination. These authors found at least 4500 genes involved in the biosynthesis of the senescence process as degradation of leaf cell components and new proteins were made, resulting in the regulated movement of nutrients and sugars from the leaf to the developing ear.

​This phenomenon is not unlike the reabsorption of leaf nutrients that occurs in many plants species and is being expressed in the Northern Hemisphere currently in deciduous trees, as the senescing leaves lose nutrients and chlorophyll, eventually abscising from the branch. The similar process in corn begins with the degradation and removal of leaf cellular contents, transportation to the fruit (grain) and eventual development of thickened cells at the base of the leaf, cutting off all movement of water and nutrients in and out of the leaf. 

​Varieties of corn surely differ in the timing and effectiveness of this senescence process.  These differences may be reflected in leaf cellular activity such as leaf disease resistance or drought stress.  The modified leaves composing the ear husk undergo the same senescing process, eventually effecting the opening of the husk needed for the evaporative drying of pre-harvest grain.  Eventually, the senescing leaves are cut off from the rest of the plant by the development of thick walls in the parenchyma cells at the base of the leaf, similar to the abscission layer known as the black layer at the base of a mature kernel.  The cutting off of the water into the leaf after the abscission layer is evidenced by the sagging of the leaf.
 
Leaf disease in a particular field may be different than last season but will be similar in some other field but the dynamics will remain.

Comments are closed.

    About Corn Journal

    The purpose of this blog is to share perspectives of the biology of corn, its seed and diseases in a mix of technical and not so technical terms with all who are interested in this major crop. With more technical references to any of the topics easily available on the web with a search of key words, the blog will rarely cite references but will attempt to be accurate. Comments are welcome but will be screened before publishing. Comments and questions directed to the author by emails are encouraged.

    Archives

    December 2021
    November 2021
    October 2021
    September 2021
    August 2021
    July 2021
    June 2021
    May 2021
    April 2021
    March 2021
    February 2021
    January 2021
    December 2020
    November 2020
    October 2020
    September 2020
    August 2020
    July 2020
    June 2020
    May 2020
    April 2020
    March 2020
    February 2020
    January 2020
    December 2019
    November 2019
    October 2019
    September 2019
    August 2019
    July 2019
    June 2019
    May 2019
    April 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    October 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    April 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015

    Categories

    All

    RSS Feed

© COPYRIGHT 2025. ALL RIGHTS RESERVED
  • Corn Journal
  • Author
  • Stalk Rot Booklet
  • Seed Testing
  • Corn Genetics
  • Pathology
  • Sponsors
  • Contact