Compost and Microbial Disease Suppression

Allison L H JackDr. Eric B. Nelson’s Laboratory Group

High Tunnel Workshop 12-8-09

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

[www.ipmimages.org]

A. Jack Cornell University 2008

vegetative hyphae

sporangium

germinating sporangium

zoosporangium zoospores

antheridium

oogonium

oogonium oospore

Germinatingoospore

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

www.nysaes.cornell.edu/ent/biocontrol/pathogens/trichoderma

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 acre 8 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

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 tubTimerSump pump(circulates 2x a day)

Zoospore pre-infection events

A. Jack Cornell University 2008

The Spermosphere

Pythiumzoospore

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 KarpEric CarrMonica MinsonEllen CrockerSarah ArnoldDave 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