1a. Objectives (from AD-416)
The fundamental goal of this research program is the development of sustainable methods fro the control of soilborne diseases of fruit trees. Thus, the objectives are to define the mechanism(s) of action for brassicaceae seed meals in the control of the pathogen/parasite complex which incites orchard replant disease, and develop and evaluate in the field novel formulations or integrated systems to attain the necessary spectrum of pathogen/parasite suppression for control of orchard replant disease.
1b. Approach (from AD-416)
This program will develop a systems approach to disease management which exploits the biological resources resident to orchard ecosystems and utilizes minimal inputs beyond that commonly employed during orchard renovation or management. This will be achieved through acquiring an understanding of the biological and chemical mechanisms involved in the brassicaceae seed meal induced suppression of the pathogen complex contributing to apple replant disease. New tools will be developed to efficiently monitor fungal community structure in these soils to garner a more complete understanding of the functional elements contributing to disease suppression and the temporal nature of the response. Enhanced efficacy of bio-active plant residues for the control of soilborne pathogens will be obtained by clarifying the role of soil microbial communities in eliciting the inhibitory activity of these plant tissues. Information from these studies will be utilized to develop and field validate biologically sustainable management strategies for control of replant diseases in conventional and organic production systems. Replacing 5350-22000-012-00D (11/07).
3. Progress Report
New orchards were established in spring 2010 on three different orchard (Sunrise, Stormy Mountain and Tukey) replant sites in Washington state to evaluate the efficacy of composite mustard seed meal amendments in concert with host tolerance for the control of apple replant disease (ARD). Two seed meal formulations when utilized in concert with the highly susceptible apple root stock M9, and the Geneva 11 rootstock which is tolerant of the parasitic nematode Pratylenchus penetrans. In addition, autumn (2009) and spring (2010) application periods were examined at the Sunrise location, whereas spring applications were made at the other experimental sites. Spring applications proved to be phytotoxic to apple at the Sunrise orchard, but trees at the other sites responded positively to the spring seed meal amendment. The different response to spring amendments at the different sites was associated with differences in soil type and organic matter content. The Sunrise orchard possessed a sandy soil with very low organic matter content; OM content was approximately 30% of that at the other two test sites. In addition, the low OM test site possessed soil microbial populations that were significantly lower. Both of these attributes likely contributed to the phytotoxic response of seed meal amendments to apple in response to spring application at the Sunrise orchard. Autumn seed meal application at the Sunrise orchard resulted in a positive growth response of apple irrespective of rootstock. An apple rootstock population obtained from the USDA-ARS rootstock breeding program in Geneva, NY was screened for resistance/tolerance to the fungal root pathogen Rhizoctonia solani AG-5. Significant variation in susceptibility to this pathogen was detected in the population, with results indicating the possibility of two or three segregating factors that explain about 50% of the variation. This progress significantly advances goals outlined in Component 1, Pre-Plant Soil Fumigation Alternatives, of National Program 308, development of new technologies for alternatives and integration into commercial crop production systems currently dependent upon methyl bromide soil fumigation.
5. Significant Activities that Support Special Target Populations
Contacts with orchardists and nursery operators regarding non-fumigant alternatives for control of soilborne plant pathogens, and in particular apple replant disease, occur on a regular basis. Contacts included the establishment of a demonstration in a small family operated organic orchard, interaction with growers at industry sponsored meetings, and frequent contact with small growers and nursery operators around the nation via electronic or voice communication. Information provided to growers is based upon findings from this CRIS concerning the development of novel non-fumigant methods for the management of replant disease that can be utilized in organic and conventional orchard production systems.
Mazzola, M., Brown, J. 2010. Efficacy of brassicaceous seed meal formulations for the control of apple replant disease in conventional and organic production systems. Plant Disease. 94:835-842.