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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGY, BIOLOGICAL CONTROL, AND MOLECULAR GENETICS OF ROOT DISEASES OF WHEAT, BARLEY AND BIOFUELS BRASSICAS Title: Chapter 6.Diseases Which Challenge Global Wheat Production- Root, Crown, and Culm Rots.

Authors
item Smiley, Richard -
item Backhouse, David -
item Lucas, Phillipe -
item Paulitz, Timothy

Submitted to: Wheat: Science and Trade
Publication Type: Book / Chapter
Publication Acceptance Date: March 20, 2009
Publication Date: September 20, 2009
Citation: Smiley, R.W., Backhouse, D., Lucas, P., Paulitz, T.C. 2009. Chapter 6.Diseases Which Challenge Global Wheat Production- Root, Crown, and Culm Rots.p. 125-153 Wheat: Science and Trade, B.F. Carver, ed. Blackwell Publishing, Ames, IA.

Interpretive Summary: With few exceptions, root, crown, and culm rots are especially prevalent in cropping systems characterized by high residue retention, reduced tillage, or high frequency of host crops. Most of these diseases are not yet effectively managed by genetic resistance, fungicides, or biological agents. Optimal disease management generally requires changing the soil environment to reduce survival of the pathogens between susceptible host crops, or the virulence of pathogens during the infective stage. 2) Rotation to non-hosts is an effective management strategy for common root rot, take-all, Cephalosporium stripe, and eyespot but not crown rot, Pythium root rot, or Rhizoctonia root rot. 3) Other management practices that reduce damage caused by several of these diseases include preventing growth of volunteer cereals and weed hosts during the interval between crops, banding a portion of the fertilizer below the seed, adjusting the planting date, using a seed drill that causes intense soil disturbance in the seed row, and protecting seedlings by applying a fungicide to the seed. Only eyespot can be controlled by applying fungicide to the foliage. Crop management systems to control take-all and eyespot are optimized using models. 4) Severity of take-all and Rhizoctonia root rot may increase at the beginning of a wheat monoculture and then begin to decline in severity. These disease decline phenomena are mediated through influences of the soil microbiota. 5) Wheat cultivars with useful levels of resistance are available to suppress damage by common root rot, crown rot, Cephalosporium stripe, and eyespot. Molecular markers are used to detect resistance genes in seedlings, and DNA-based real-time PCR assays are available to identify and quantify these pathogens in soil or plants. PCR plus data interpretation based on disease epidemiology has been used commercially to predict potential grain yield loss from several of these diseases.

Technical Abstract: With few exceptions, root, crown, and culm rots are especially prevalent in cropping systems characterized by high residue retention, reduced tillage, or high frequency of host crops. Most of these diseases are not yet effectively managed by genetic resistance, fungicides, or biological agents. Optimal disease management generally requires changing the soil environment to reduce survival of the pathogens between susceptible host crops, or the virulence of pathogens during the infective stage. 2) Rotation to non-hosts is an effective management strategy for common root rot, take-all, Cephalosporium stripe, and eyespot but not crown rot, Pythium root rot, or Rhizoctonia root rot. 3) Other management practices that reduce damage caused by several of these diseases include preventing growth of volunteer cereals and weed hosts during the interval between crops, banding a portion of the fertilizer below the seed, adjusting the planting date, using a seed drill that causes intense soil disturbance in the seed row, and protecting seedlings by applying a fungicide to the seed. Only eyespot can be controlled by applying fungicide to the foliage. Crop management systems to control take-all and eyespot are optimized using models. 4) Severity of take-all and Rhizoctonia root rot may increase at the beginning of a wheat monoculture and then begin to decline in severity. These disease decline phenomena are mediated through influences of the soil microbiota. 5) Wheat cultivars with useful levels of resistance are available to suppress damage by common root rot, crown rot, Cephalosporium stripe, and eyespot. Molecular markers are used to detect resistance genes in seedlings, and DNA-based real-time PCR assays are available to identify and quantify these pathogens in soil or plants. PCR plus data interpretation based on disease epidemiology has been used commercially to predict potential grain yield loss from several of these diseases.

Last Modified: 10/25/2014
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