Friday, July 25, 2008

Dockage Due to DON Levels in Wheat is Being Reported in SW WI

Tim Wood, the Director of the Lancaster Research Station, reported today (7/25/08) that a few wheat samples have tested positive for DON (vomitoxin) in SW WI. These samples were collected from wheat fields where low levels of Fusarium head blight (FHB) were noticed prior to harvest. The DON levels in the positive samples were 2.6 and 3.0 ppm. A usual cutoff for DON levels is 2 parts per million or lower in wheat. A local elevator was assessing dockage fees of $0.25/bu for DON levels over 2.0ppm.

Image 1. Scabby and Tombstone Kernels
(Photo courtesy of Laura Sweets)

As a point of reference the UW Winter Wheat Variety Trial located at the Lancaster Research station was our most uniform and prevalent FHB site. Our ratings at Lancaster showed a FHB index range from 0.6 to 8.8 among the varieties. This FHB index is based on a range from 0 to 100 where 0 indicates no signs of scab infection and 100 means all heads in the field are completely infected. The 0.6 rating was found in the public variety “Truman”, which has resistance to head scab.

Image 2. Spikelet infected with FHB.
(Photo courtesy of Laura Sweets)

As we continue with wheat harvest and grain delivery remember that having FHB does not automatically mean that the grain will have a concentration of DON, and second, there is evidence that healthy looking kernels can test positive for DON. Therefore, if you are concerned that there is mycotoxin contamination, consult the Pest Management in Wisconsin Field Crops – 2008 (UW-Extension, A3646) in the corn disease section where a list of laboratories that conduct mycotoxin tests is listed. DON infected wheat can be blended with non-infected wheat to reduce the overall concentration.

Please contact Paul Esker if you learn of positive finds in your county at: or 608-890-1999.