Compost and Microbial Disease Suppression Allison L H Jack Dr. Eric B. Nelson’s Laboratory Group High Tunnel Workshop

Overview Biologically based disease management Known mechanisms of biocontrol Pythium suppressive vermicompost & liquid vermicompost extract –How these materials are used for nutrient management –Disease suppression in this system Conclusions

Example: Pythium spp. (damping off) Post-emergence damping off [

A.Jack Cornell University 2008 vegetative hyphae sporangium germinating sporangium zoosporangiumzoospores antheridium oogonium oospore Germinating oospore asexual sexual direct indirect DISEASE [modified from Matthews 1931] P. aphanidermatum

Mechanisms of biocontrol Single organism: –Antibiosis –Competition for nutrients –Parasitism –Induced systemic resistance Multiple organism: –Much more complicated!

Antibiosis Root surface Bacillus subtilis “Kodiak TM ” Zwittermicin A (antibiotic) [Shang et al. 1999] Pythium zoospore

Competition for nutrients Seed exudates Cucumber seed Linoleic acid Pythium sporangium [van Dijk and Nelson 2000] Enterobacter cloacae Linoleic acid Pythium sporangium

Induced Systemic Resistance (ISR) Pseudomonas corrugata Pythium sporangium [Chen et al. 2000]

Parasitism

Multiple organism biocontrol Often associated with high microbial biomass and activity Unclear which organisms are involved and how they interact with each other Goal: –Understand how disease suppression works in a single system so we can make the practice more effective

Solid vermicompost Simple feedstock + process control = more consistent product OMRI listed Potting media amendment –5-20% depending on crop Liquid vermicompost extract Soil drench applied when irrigating High in micronutrients Can provide comparative levels of suppression with 200 x less compost Can be freeze dried and reconstituted

Soil applications - garlic 2 t per acre 4 t per acre8 t per acre [Rangarajan, Leonard & Jack, ongoing]

Cabbage trials Organic materials rely on microbial activity to mineralize nutrients and make them plant available - results are temperature sensitive Control Blood meal 10% VC & BM [Rangarajan, Leonard & Jack, ongoing]

Vermicompost is added to tops of plug trays, aerated vermicompost extract is piped directly into overhead irrigation

Aerated compost extract Expensive equipment ($20,000) No shelf life Additives needed Cheap equipment ($250) Long shelf life No additives needed Non-aerated compost extract sump [Elzinga Hoeksema Nurseries, MI] 100 gallon tub Timer Sump pump (circulates 2x a day)

Zoospore pre-infection events

A.Jack Cornell University 2008 The Spermosphere Pythium zoospore cucumber seed Seed exudates

Conclusions Using compost can be a valuable cultural practice for suppressing disease Scientific understanding is not at a level where we can make predictions for specific composts Look for composters who closely manage their production process for a consistent product

Acknowledgements Nelson Lab: Mary Ann Karp Eric Carr Monica Minson Ellen Crocker Sarah Arnold Dave Moody My committee: Eric Nelson (PPPMB) Anthony Hay (MICRO) Anu Rangarajan (HORT) Kathie Hodge (PPPMB) Scott Peters (EDUC) Financial support: Department of Plant Pathology and Plant Microbe Biology USDA BARD Knight Institute for Writing in the Disciplines New York Farm Viability Institute NYSTAR Center for Advanced Technology & USDA SBIR Phase I & II (with Worm Power) Organic Farming Research Foundation Organic Crop Improvement Association Andrew W. Mellon Fellowship Kent Loeffler – photo credits SBIR Program Industry collaborator: Tom Herlihy Worm Power