National Scab Research: Success Ultimately In Integrated Solutions Emphasizing FHB Management

by Tracy Sayler

After Fusarium Head Blight (scab) devastated Northern Plains wheat and barley in 1993 and the northern Corn Belt in 1996, the disease began to move higher on the federal research radar screen.

It was one of several plant disease complexes accorded special status as “Emerging Diseases” in federal budgets in 1995 and 1996. The USDA earmarked $200,000 to the problem with end-of-year funds in federal fiscal year 1997, and soon after, a comprehensive research effort was organized to focus on the problem. The U.S. Wheat and Barley Scab Initiative now accounts for about $5 million annually in federal research on scab, conducted across the country by about 100 principal investigators at about two dozen land grant universities, as well as USDA-ARS and the International Maize and Wheat Improvement Center (CIMMYT).

From FY99-FY05, the federal government through the USWBSI has invested about $32 million on the scab problem.

So what’s been accomplished?

Obviously, no ‘silver bullets’ have been found, although none were expected.  Still, research and knowledge of the disease has progressed well beyond addressing the initial basic questions, such as ‘what is this’ and ‘why is it occurring?’

David Van Sanford is a wheat breeder at the University of Kentucky, and serves as one of two co-chairs of the USWBSI, the other being Tom Anderson, a Barnesville, MN grower.  Van Sanford briefed attendees of the 2006 Wheat Congress (annual meeting of the National Association of Wheat Growers) about the ongoing research efforts of the USWBSI.

He says that since the 1990s, improving scab resistance has become a virtual prerequisite to developing wheat varieties in scab-affected areas. This has been challenging, given a limited number of scab resistance sources, but that will improve over time. 

While better genetics hasn’t eliminated scab as a threat – and may never – the release of more resistant and partially resistant varieties has certainly reduced the risk. Van Sanford points to six HRSW varieties developed in the Northern Plains since 2000 with a higher level of scab resistance than many varieties available in the 1990s (Alsen - ND 2000; Oklee - MN 2003; Steele - ND 2004; Granger - SD 2004; Glenn - ND 2005; Ulen - MN 2005) with more on the way. There has been notable breeding progress in soft red and white wheat varieties as well, and release of more resistant durum and barley germplasm for breeders to use in crosses.

Now, there is a systematic means of uniformly screening and evaluating germplasm and varieties, says Van Sanford, with fewer VS (very susceptible to scab) varieties developed and grown.

Van Sanford says there is now routine, efficient use of molecular markers to identify scab resistant (and scab susceptible) genes.  Transformation methods and some genetically-engineered lines have been developed, but biotech research is highly expensive to conduct, and with limited funding, biotechnology is an area that is a bit of a quandary for the USWBSI. “Can we afford to do this (biotech) research?” asks Van Sanford, rhetorically.  “Can we afford not to?”

The scab pathogen (Fusarium graminearum) genome has been sequenced, and this may reveal weaknesses that can be exploited by breeding, fungicides, and biological controls, says Van Sanford. Other accomplishments include a multi-state FHB Forecasting System (estimated to be about 80% accurate in spring wheat last year) as well as greater knowledge about fungicide control and application technology.

Van Sanford says USWBSI objectives need more research focus on DON/vomitoxin as well as communication, including a better, ‘friendlier’ web page and more communication with growers, millers, and bakers.

Ultimately, success will come in seeking integrated solutions emphasizing FHB management, rather than control. “Successful solutions will involve the best genetic resistance we can find or engineer, the best fungicides and delivery systems, the best cultural practices, and a forecasting system that ties all of the pieces together,” Van Sanford says.

A review of USWBSI research can be found online at www.scabusa.org. See details of research completed within the past year under ‘Annual Forums.’