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United States Department of Agriculture

Agricultural Research Service

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Research Project: A survey of Rhizoctona groups on wheat and barley in the Continental U.S.

Location: Root Disease and Biological Control Research

2011 Annual Report


1a.Objectives (from AD-416)
Survey wheat growing areas of the United States for Rhizoctonia groups and species infecting cereals (wheat and barley) and rotation crops.


1b.Approach (from AD-416)
Soil samples will be sent to Pullman by Syngenta staff and other University and ARS cooperators. Rhizoctonia will be isolated from the soils, cultured, and identified using sequencing of the ITS region. Representatives isolates will be tested in greenhouse for pathogenicity. Documents Trust with Syngenta. Log 39949.


3.Progress Report

Progress aligns with objective 1 from parent agreement. Root diseases, including take-all, Pythium, Rhizoctonia and common root rots, and Fusarium crown rot, cause $3.5 billion in losses annually to U.S. wheat and barley growers. For most of these diseases, there are no resistant varieties and chemical treatments are not available or perform inconsistently. Modern production practices of reduced tillage and direct seeding, used to control soil erosion, exacerbates the incidence and severity of root diseases. Over the last 30 years, a large amount of research on Rhizoctonia has been conducted in the Pacific Northwest, but little is known about Rhizoctonia in other wheat growing areas of the US. ARS scientists at Pullman, WA in collaboration with scientists at Syngenta are collaborating to survey all major cereal growing areas in the U.S. for Rhizoctonia species. Using their network of field and sales reps, Syngenta is collecting soil samples from all of these areas and shipping them to Pullman. As of May, 2011, 132 samples were analyzed, and 54 isolates were identified from 39 locations. The most predominant groups were Rhizoctonia oryzae group I and R. solani AG 2-1. Surprisingly, AG-8, the cause of classic Rhizoctonia bare patch, was not found outside of the Pacific Northwest. Pathogenicity testing in the greenhouse showed that AG-8 was the most virulent on wheat and barley, but AG 2-1, 3, and 4 could also cause reductions in height and plant biomass. This study is providing the first national survey of Rhizoctonia on small grains and is greatly increasing the capacity of ARS and Syngenta to respond to outbreaks of this important root pathogen.


Last Modified: 9/22/2014
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