Pythium and Fusarium species get the most attention as being associated with seedling rot. These fungi are only marginally aggressive, however, mostly infecting plants that are weakened either from damage to the seed or from environmental stress.
Each seed within a lot has a separate experience as it develops in the production field. Position on the ear and synchrony of silking on the female parent and pollen production from the male parent affects the shape of the corn kernel. Resulting shape and size influences the vulnerability to damage during harvest, drying and handling within the production facility. Genetics of the female parent also affects the vulnerability to imbibition damage as well.
Environmental factors affect the duration from germination to eventual independence upon the transport of nutrients from the seed endosperm and water and minerals via seminal roots. Water is needed but too much water can limit oxygen supply to the submerged cells and thus limiting growth. Heat energy greatly affect the speed of metabolism and resulting cell elongation of the mesocotyl cells. Heavy soils with high clay content can present physical barriers. Feeding by soil insects and nematodes can offer avenues for soil fungi to enter the mesocotyl tissue.
Nearly everyone involved from the beginning of seed production to planting the seed can affect the establishment of a good final stand in the field. Good luck with the uncontrollable environmental factors also helps.
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.