2013 Annual Report
1a.Objectives (from AD-416):
The objectives of this cooperative research are to identify, characterize and control soilborne pathogens of wheat and barley, such as Rhizoctonia, Pythium, Gaeumannomyces, Bipolaris and/or Fusarium, which cause root and crown rot diseases; to identify the effects of cropping systems on root pathogen population size and diversity, and on disease epidemiology; and to identify wheat and/or barley germplasm with resistance/tolerance against root diseases.
1b.Approach (from AD-416):
Root and crown rot diseases will be identified and characterized through a combination of laboratory, greenhouse and field studies. The ecology of soilborne pathogens and effects of cropping system on pathogen population size and diversity and disease epidemiology will be determined using plant pathology, microbiology and molecular biology methods. Wheat and barley germplasm will be screened for resistance or tolerance to soilborne pathogens in the field and greenhouse. Practical root disease control will be accomplished through a combination of agronomic practices and biological and chemical treatments.
This research relates directly to Objective 1 of the parent project, "Evaluate the pathogenic diversity, host range, and geographical distribution of fungal and nematode root pathogens, and the influence of cropping systems on soilborne diseases". Soilborne pathogens cause significant losses in wheat and barley production nationwide. There is little genetic resistance available in these crops to combat soilborne fungal pathogens such as Fusarium culmorum. ARS collaborators at the University of Idaho, Idaho Falls, carried out the eight year study of a foot rot screening project at a nursery in Aberdeen; dozens of wheat and barley varieties and lines have been ranked for levels of resistance/tolerance. There were significant differences between varieties for yield and stand, allowing identification of varieties that are better adapted to yield under Idaho conditions with substantial disease pressure. Identification of germplasm with resistance or tolerance to infection will assist in the development and recommendation of varieties that perform best under Idaho dryland conditions where Fusarium crown and foot rot prevails, thus reducing associated yield losses. Environmental conditions in high elevation areas of the Inland Pacific Northwest limit some crop production to continuous cereals, exposing crops to high disease pressure. Researchers at the University of Idaho, Idaho Falls, continued to test commercial fungicides in a dryland winter wheat production system for effectiveness against Fusarium crown rot. While some chemical seed treatments may reduce some symptoms of root and crown disease, there usually is no yield benefit. Growers must continue to rely on management practices and potential new varieties to control soilborne disease. Precipitation in the last ten years remains below the 30-year average, raising the possible necessity of returning to a summer fallow production system. Grain production has also suffered from soilborne disease, nematode and insect problems. ARS collaborators at the University of Idaho, Idaho Falls, evaluated the agronomic performance and economics of wheat under four different production systems:.
2)continuous conventional no-till,.
3)green manure, and.
4)plowing. Long-term studies indicate that there will be a shift in disease problems with changing management practices. In a study at a site with continuous grain for twenty years, lab analysis showed damaging levels of nematode populations (lesion, stubby root, stunt, dagger and cereal cyst nematodes) throughout the field, and wireworm pressure was very high. Crop rotations significantly affected populations of parasitic nematodes.