Management of Allium White Rot

2012 Annual Report for FNE11-721

Project Type: Farmer
Funds awarded in 2011: $8,301.00
Projected End Date: 12/31/2012
Region: Northeast
State: Maine
Project Leader:
Amy LeBlanc
Whitehill Farm

Management of Allium White Rot


Our goal is to examine the concept of biostimulation as a possible management tool for the fungus Allium White Rot (Sclerotium cepivorum). There are no fungicides acceptable for use on an organic farm that will affect control of Allium White Rot (AWR). We would like to show that biostimulation, coupled with rogueing of volunteer alliums, a strict sanitation protocol, and a 4-year rotation will allow acceptable management of this devastating disease.

Following the recommendations of Dr. Fred Crowe (Professor Emeritus, Oregon State University) we harvested healthy garlic green material from our 2010 crop, processed it and froze it to use in the spring of 2011.

In the first spring of our project (2011) we divided six raised beds into three sections each using permanently installed deep wooden dividers. At that point we began our sanitation protocol: all soil is to stay in the beds, hands, tools and wheelbarrows will be washed before moving to a new section, shoes and boots, stakes, tomato towers, will be washed, etc. We rogued out a few allium plants left from previous seasons and they were destroyed.

We then took soil samples from each of the 18 sections. The samples went to a California lab, Nematodes, Inc., which specializes in allium diseases. The report we received showed a significant amount of AWR pathogen in each section.

We then applied the biostimulation treatments. The treatments were: fresh garlic juice, applied in water at a rate of 4 tablespoons to 4 gallons of water; green garlic material from the previous year and thawed. We dug both treatments into the soil to a depth about 8-10 inches. The third section of each bed was not treated, as a control. We then planted the beds to regular garden crops other than alliums. The treatments were applied in a randomized pattern – which we will continue to use – and replicated in two different areas of our raised bed gardens.

In the spring of 2012 we repeated the process: soil samples were sent to Nematodes, Inc. for assay of the AWR pathogen; we planted regular non-allium crops and cover crops in the 6 raised beds. Later, in July, we received the results of the lab tests. There was a dramatic – TOO dramatic – improvement in the numbers. After some consultation with Dr. Crowe we decided to take it as a demonstration of the variables (See #3). With additional results we’ll have a clearer picture.

As we write, in December 2012, winter temperatures are putting any remaining sclerotia into dormancy. When the soil warms in the spring of 2013 we’ll repeat the process of samples for lab tests, and planting to non-allium crops. With the base-line assay – spring 2011 – and the two additional assays – 2012 and 2013 – we will be able to make a more accurate assessment of our progress.

We have already shared information about our project at an Open Farm Day, two Adult Ed Classes, and during a presentation (with Dr. Steve Johnson, University of Maine Extension Crop Specialist) at the 2012 Maine Agricultural Trade Show. In 2013 I plan to make presentations at the NOFA Summer Conference, Maine Open Farm Day, and other opportunities as they arise.


The second set of test results came back in the summer of 2012. The results showed significant reduction in the pathogen. We went into this project knowing that there are some variables we cannot control and that the test results may not yet be conclusive. Simple variables include the difficulty of digging samples from the exact same spot or depth, and torrential rains which can also move the pathogen.

We are confident that our 2013 test results will allow us to average the results, giving a better picture. We have also applied for a second Farmer Grant to allow us to continue this study for another two years. The goal is to plant a mixed allium crop in each of the test beds in the spring of 2015: short term spring onions, to be removed mid-season; and storage onions to mature through the season. We will then have the crops tested for presence of the AWR pathogen.

An unanticipated expense resulted from the realization that our existing compost could probably be contributing to the spread of AWR. So in January of 2012 we had a local builder remove the 14 bins and the contents, including an area a foot below grade and several feet to the sides of the bins. The entire mess is now fill under a building and will not see the light of day or a plow.

A dramatic (duh) realization that our compost was probably contributing to the spread of AWR on our farm was sobering …and gave new meaning to the words ”sanitation protocol”. In addition to our original concepts (cleaning tools, wheelbarrows, boots, plant supports, destroying all plant debris, etc.) we have added additional layers of safeguards. The areas between our raised beds are mown grass: we now have a dedicated mulching mower to mow in the AWR contaminated area. After the old compost area was removed, we have built new compost bins and are carefully managing what goes into the bins. Even in our kitchen, root crops need to be trimmed into the landfill bag …we can’t risk adding that material to our own compost. Our chickens will never be truly free range again…

The dramatic first year lab test results have shown that the anticipated variables are certainly very real. We really need additional tests to confirm the improvements.

The overall big picture at Whitehill Farm hasn’t changed. We are still a small hand-tool based operation raising herbs, dried flowers, peppers, Asian greens, lots of tomatoes and our own family vegetables. The only significant change is that we are building new raised beds every year, away from the AWR contaminated area, with new soil and using new and dedicated tools, to allow us to continue growing garlic. These new beds are necessary as garlic is an essential ingredient in many of our value-added culinary herb products

There are no specific site conditions affecting our project at this time.

Dr. Fred Crowe (Professor Emeritus, Oregon State University) continues to be our main mentor. His guidance and enthusiasm have been invaluable. Dr. Crowe is also assisting growers in Ontario, Canada and up-state New York, and hopes to visit with all of us in 2013. Our local University of Maine Extension Crop Specialist, Dave Fuller, is our connection to state diagnostic labs. We have been working closely with Mr. Fuller, both for advice on good growing practices for garlic and to stay up-to-date with other current research.

Mr. Fuller and Dr. Steve Johnson are working together on another SARE grant, #LNE11-306, working to develop a way to produce disease free garlic planting stock. Both Mr. Fuller and Dr. Johnson have been providing advice through this entire project.

Dr. Eric Sideman, Organic Crop Specialist for MOFGA, has also been instrumental in keeping us attuned to pest and disease issues here in Maine.


David Fuller
Agricultural and Non-Timber Forest Products Professional
U. Maine Cooperative Extension
138 Pleasant Street
Farmington, ME 04938
Office Phone: 2077784650
Dr. Steven Johnson
Crops Specialist, Aroostook
University of Maine
Aroostook County Extension Office
Presque Isle, ME 04769
Office Phone: 2077643361
Dr. Eric Sideman
Organic Crop Specialist
P.O. Box 170
294 Crosby Brook Road
Unity, ME 04988
Office Phone: 6032696201
Dr. Fred Crowe
Emeritus Professor of Botany & Plant Pathology
Oregon State University
114 Pie Plant Hollow
Dayton, WA 99328
Office Phone: 5414206633