Wheat Crop Challenges

Fusarium Head Blight

Fusarium head blight (FHB), or scab, is a fungal disease that can occur on all classes of wheat in the U.S., but is seen most commonly on spring and winter wheat, durum and barley. FHB can cause significant yield losses and quality reductions. Yield losses in wheat occur from floret sterility; additional yield and quality losses can occur when shriveled, light test-weight kernels are produced as a result of infection. Quality reductions also may occur if fungal toxins (mycotoxins) are produced in infected seed. The toxins are unacceptable for certain end uses, so toxin-containing grain is downgraded at the market. Wheat growers use many tools to manage this disease as a result of the unacceptable quality affect, and are constantly seeking more effective technology to combat the disease.

Rusts

U.S. wheat production and world food security are at risk due to devastating cereal rust diseases including Ug99 wheat stem rust. Unlike other diseases that may reduce yield or quality, stem rust can kill the entire plant. Research is being done to assess U.S. wheat varieties’ vulnerability to Ug99, and to identify resistant genes for breeding into new varieties. Improved variety and germplasm development is the only way to get ahead of and minimize the effects of Ug99 when it arrives in the U.S.

In addition to the risk of Ug99, current challenges include leaf rust and stripe rust that cause serious losses in U.S. wheat production nearly every year. Rust pathogens evolve rapidly and have overcome many important genes for resistance.

Pests and Insects

Reducing damage from insect pests requires integrated approaches and collaborative research specific to each major production region. Cooperation between USDA/Agricultural Research Service (ARS) and land-grant universities is crucial in this fight.

Russian wheat ahphid, Hessian fly and wheat stem sawfly are three insects that are becoming increasingly virulent and must be addressed.

Genetic resistance remains the most environmentally responsible and effective strategy to control these insect pests and others over the long term. However, new genetic sources of resistance and more rapid, effective screening methods are needed to achieve durable resistance. Also needed is a greater understanding of insect biotypes, their evolution and the mechanistic basis of insect virulence and host resistance.

Quality

Four USDA regional wheat quality labs – in Pullman, Wash., Fargo, N.D., Manhattan, Kan. and Wooster, Ohio – are crucial in supporting wheat breeders with information and tools to enhance the value of the U.S. wheat crop. The world wheat market is increasingly sophisticated and requires higher grain, processing and product quality, nutrition and food safety. The USDA/Agricultural Research Service (ARS) wheat quality labs need the equipment and staff to meet those demands.

The labs are working to determine the biochemical, molecular and genetic properties responsible for end-use quality, functionality and nutritional composition. Specific genes and markers associated with superior wheat quality and end-use functionality have been identified, with more to follow. Test methods have been developed that will allow for more rapid screening of early generation experimental lines for milling and baking quality.

Genomics

Today, public wheat breeders use DNA markers to make breeding more accurate at a lower cost. This advanced utilization of wheat genomics is possible because of USDA/Agricultural Research Service (ARS) investments in regional genotyping labs, USDA/National Institute of Food and Agriculture (NIFA) funding of coordinated agricultural projects and growers’ investments through checkoff dollars to state university programs.

Wheat needs additional investments in pre-competitive basic science to broaden the availability of genomic resources and facilities that can make full use of these tools. We strongly encourage USDA’s Agriculture and Food Research Initiative (AFRI) to prioritize participating in the international work toward completing the sequencing of the wheat genome by supporting work on the chromosomes assigned to U.S. scientists.