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United States Department of Agriculture

Agricultural Research Service

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Research Project: Development of Disease Resistant Walnut Rootstocks: Integration of Conventional and Genomics Approaches (Propagation of Germplasm for Tcd)

Location: Crops Pathology and Genetics Research

2013 Annual Report


1a.Objectives (from AD-416):
Evaluate the J. nigra germplasm collection in Missouri for susceptibility to Thousand Cankers Disease.


1b.Approach (from AD-416):
Mutiple clonal replicates of each accession of the largest collection of J. nigra germplasm at the University of Missouri will be propagated and provided to the University of Tennessee where they will be screened for Thousand Cankers Disease susceptibility.


3.Progress Report:

This project was established in support of objective 1 of the in-house project, which is to characterize the etiology, biology, and ecology of key phytopathogenic agents and their interactions with economically important tree and grapevine species. The goal of this project is to evaluate the j. nigra germplasm collection in Missouri for susceptibility to Thousand Cankers Disease.

During FY2013, progress at both the University of Missouri (MU) and the University of Tennessee (UT) continued to focus on the propagation and subsequent deployment of walnut (Juglans sp.) germplasm resources for the purpose of screening for susceptibility to Thousand Cankers Disease (TCD), caused by Geosmithia morbida, a fungal pathogen first found in Knoxville, Tennessee. Since this discovery in 2010, TCD has also been identified in North Carolina, Ohio, Pennsylvania and Virginia. As such, the threat posed by this disease to both the black walnut nutmeat and timber industry is considered to be significant, now that it has been identified in multiple locations throughout the eastern deciduous forest.

Seedling populations of black walnut (J. nigra), representing eight states, were established in three “common garden” plantings in Pennsylvania, Tennessee and Virginia, in the spring 2012. One additional clonal test of black walnut (representing elite sources from the MU germplasm collection) was established in Richmond, Virginia (within the quarantine zone). An additional set of the same germplasm was delivered to UT in FY2013 and will be established in the field in the spring 2014.

In FY2013, 1,000 black walnut seedlings were established at UT to serve as rootstocks for future grafting work related to this project. Additionally, a total of 1,060 grafts, representing 110 accessions of six different Juglans species and/or hybrids were propagated at MU. These accessions represent both nut cultivar and timber selections derived from the MU breeding program. In addition, grafts from 19 black walnut accessions representing 11 different states were also propagated in FY2013. Plans call for the majority of these containerized grafts to be transported from MU to UT in September, 2013, and subsequently outplanted in the spring 2014.


Last Modified: 7/24/2014
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