Stalk rot, lodging and fungicides
Factors leading to deterioration of corn stalks are complex, as discussed previously. In most cases the direct loss of strength comes from premature death of the plant in which it suddenly wilts before completion of grain fill. This is preceded with destruction of roots by soil fungi due to reduction of cellular resistance. This happens when the upper plant cannot adequately supply carbohydrates for maintenance of those root cells as sugars are also moved to the grain.
The wilting of plant results in withdrawal of the pith tissue from the rind, essentially changing the strength of the stalk from a rod to a tube. Stalk cell death also reduces the resistance to the fungi feeding on the cellulose and pectin of the rind, further weakening the stalk strength.
Fungicides could be affecting those stalk invading fungi but also could be reducing leaf pathogens during the grain fill period and therefore reducing loss of photosynthesis. This would potentially provide more carbohydrates to the roots and therefore avoiding the premature death and wilting that started the stalk strength weakening. It would be interesting to see that hypothesis tested.
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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.