Compost for Management of Plant Pathogens and Weed Seeds

2010 Annual Report for ONE10-123

Project Type: Partnership
Funds awarded in 2010: $15,000.00
Projected End Date: 12/31/2011
Region: Northeast
State: Vermont
Project Leader:
Dr. Deborah Neher, PhD
University of Vermont

Compost for Management of Plant Pathogens and Weed Seeds


We propose to demonstrate that compost, properly made, will kill disease early blight inoculum and weed seeds during the composting process, and that the resultant compost can be used to suppress early blight in the field. Both weed seeds and plant pathogens present economic and management challenges to growers, and low-input methods for addressing these challenges will help to further advance sustainable farming practices. Known quantities of early blight inoculum and crab grass seed were contained in two types of bags (to separate biotic from abiotic effects) and inserted into compost piles of four different recipes: 1) manure similar to what farmers create (‘compost’ but not to recipe), 2) proper recipe with hay, 3) proper recipe with softwood, and 4) proper recipe with hardwood. Each recipe was replicated in three piles.

Objectives/Performance Targets

We plan to demonstrate that compost, properly made, will heat and kill disease early blight inoculum and weed seeds. Proper compost recipe involves a proper C:N, aeration to achieve temperature targets known to kill fungal pathogens (150oF) and seeds of common weeds (175 oF) of vegetable and small berry crops. Biological control strategies support organic and low input practices. Using compost as part of the management package keeps more nutrients and organic matter on the farm and saves purchase of external inputs.

Pathogen and weed seed bags were removed from each of 12 piles at three times during the compost process: baseline, compost duration required for organic certification, and end of the thermophilic phase. Pathogen viability and seed germination assessment has been completed for approximately half of the samples, with the reminder to be processed in January 2011. To date, properly made compost appears to effectively kill the early blight pathogen and weed seeds by the time compost attains organic certification requirements.

In summer 2011, we will conduct a proof of concept project to demonstrate that compost will suppress early blight at Intervale Community Farms (ICF) and a partner farmer in Hardwick, Vermont.


Development of the compost recipes and piles in collaboration with Highfields Center for Composting worked as expected with one exception. The exception was that the cost of feedstock materials for compost and labor costs were higher than expected. We were able to save transportation costs by having the Highfields staff overnight mail samples to Burlington. The undergraduate student that was planning to assist with the project discontinued his involvement half way through the project. Therefore, processing the samples is behind schedule. However, we have hired another research assistant to complete the data collection.

For the summer 2011 trial, we had originally planned to partner with High Mowing Organic Seeds. However, they are no longer able to partner with us. Fortunately, Tom Gilbert, of Highfields Center for Composting, is assisting us in locating an alternative partner farmer in the Hardwick, Vermont area.

Impacts and Contributions/Outcomes

Highfields Center for Composting provides informational resources (such as workshops, lectures, and technical materials) and technical services in on-farm composting to farmers throughout Vermont, the Northeast and elsewhere in the US. Highfields staff directly reaches 100-300 farmers or more per year through workshops, lectures, and other presentations, and an immeasurable number of producers at events and through media. Through these avenues Highfields staff is able to effectively communicate the results of our research and trials to the farm community.


Tom Gilbert

[email protected]
Executive Director
Highfields Center for Composting
P.O. Box 503
21 Mill Street
Hardwick, VT 05843
Office Phone: 8024725138
Andy Jones

[email protected]
Invervale Community Farm
128 Intervale Road
Burlington, VT 05401
Office Phone: 8026582919
Bruce Kauffman

[email protected]
Riverside Farms
117 Riverside Farm Lane
East Hardwick, VT 05836
Office Phone: 8024726169