Recently on Twitter there was discussion regarding declining Fusarium levels on seed that has been stored in the bin from a previous season.  One Tweep went as far as saying that it would test negative after storage.  Is that the case???

"The short answer from what I know is it's possible", says Trevor Blois, Disease Diagnostician with 20/20 Seed Labs Inc.

Generally speaking, most seed-borne pathogens will decline in storage over time.  They require a healthy, growing host in order to proliferate.  While they are in the seed, or stubble they will be in a dormant state, so while they can overwinter happily in the stubble, several years of this with no host will result in that fungus eventually dying, hence the importance of crop rotation in the management of disease.  Provided that there are low moisture levels present in the storage conditions you would expect a gradual decline in the viability of the pathogen as well.  If you have poor storage conditions you'll sooner see species like Penicillium and Aspergillus spread that will make F. graminearum inconsequential at that point.  You should not see an increase of different seed-borne fungi because the systemic infection is established at flowering and little or no seed to seed spread should occur in storage.  There is not a lot of information on Fusarium in wheat, but this article http://www.cabi.org/ISC/abstract/19971005705 shows the decline in Fusarium spp. in maize in sealed containers.

This article shows the general decline in most pathogens over several years in storage for perennial ryegrass.

http://www.researchgate.net/profile/Barbara_Wiewiora/publication/249967871_Rhizoctonia_solani_and_other_fungi_detected_in_perennial_ryegrass_seeds_after_harvest_and_storage/links/02e7e51e780498248c000000.pdf

 The big problem with doing this to deal with an F. graminearum infection is that you’ll have a decline in seed quality, germination and vigour.  I would never recommend it as a management strategy because the levels just might not change at all, and now you’ve used storage space for seed that isn’t worth it to plant next year.  You’re probably better off buying new certified seed with low levels of Fusarium...or better yet, seed that has tested negative.

Contact Trevor at 1-877-420-2099 or trevor@2020seedlabs.ca

For more information on Fusarium please read the following Tech Bulletins:

http://www.2020seedlabs.ca/category/tech-bulletins/fusarium