There is a link between roundup use and fusarium disease in spring
wheat. No or minimal til using roundup seems to lead to accumulation
and overwintering of fusarium in the crop debris. There is a similar
effect related to roundup and fusarium sudden death syndrome in soy.

Published in Crop Sci 45:1908-1916 (2005)
DOI: 10.2135/cropsci2004.0197

Crop Production Factors Associated with Fusarium Head Blight in Spring
Wheat in Eastern Saskatchewan M. R. Fernandeza,*, F. Sellesa, D.
Gehlb, R. M. DePauwa and R. P.
Zentnera
a Semiarid Prairie Agricultural Research Centre, Agriculture and
Agri-Food Canada, P.O. Box 1030, Swift Current, SK, Canada S9H 3X2 b
Indian Head Research Farm, Agriculture and Agri-Food Canada, P.O. Box
760, Indian Head, SK, Canada S0G 2K0

Fusarium head blight (FHB) has been increasing in western regions of
the Canadian Prairies. The objective of this 4-yr study was to
identify crop production factors (CPF), associated with FHB
development in spring wheat (Triticum aestivum L.). From 1999 to 2002,
659 crops were sampled in eastern Saskatchewan for FHB levels, and
information gathered on agronomic practices used on these fields. In
2000 and 2001, percent Fusarium-damaged kernels (FDK) was also
determined. Differences in the FHB index among years indicated that
environment was the most important factor affecting disease
development. The effects of CPFs on FHB were lower in years with high
(2001) and low (1999 and 2002) disease pressure, compared with a year
with moderate (2000) disease pressure. Previous application of
glyphosate [N-(phosphonomethyl)glycine] formulations (GF) within
tillage system, tillage system, previously grown crop, and cultivar
susceptibility were the only CPFs that affected FHB. GF application in
the previous 18 mo within tillage system was significantly associated
with higher FHB levels every year; it was the only CPF in 1999, and
one of two CPFs in 2002, that affected FHB, suggesting that its effect
was not influenced as much by environmental conditions as that of
other CPFs. Percentage FDK was also higher in fields previously
treated with GF in 2000 and 2001. Because of the nature of this study,
we could not determine if the association between previous GF use and
FHB development was a cause–effect relationship. Thus, further
research is needed to elucidate the nature of this association and the
underlying mechanisms.




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