De-slugging the Woods: Maple-mushroom-duck polyculture proving to be ecological, economical, and enjoyable for the farmers.

Note: This article appears in the Winter 2014 – 15 Issue of the Permaculture Activist (#95)

It is said that the only sure things in life are death and taxes. As a farmer, I am inclined to add crop pests to this list. This follows basic ecological thinking; that any crop yielding a large population of food will support the increase of pest and disease pressure, since though an abundant food source, one has essentially created the conditions for a pest population to survive, thrive, and reproduce.

With mushroom farming, the pest is slugs. Slugs are a curious creature; slow, without vision, attracted to the aroma given off by sporulating fungi. Combine that appeal with wet conditions and you have a recipe for an explosion of slugs. They seem to appear overnight and quickly overwhelm fruiting logs. Picking slugs off mushrooms and logs a very undesirable (read: gross) activity, not to mention that damaged caps are sellable for the full value. In my work with the Cornell Small Farms program[i], I engage with shiitake farmers around the northeast, and we frequently moan over the inevitable slug chores that come with the profession.

Emerging solutions

A few years back, my wife Elizabeth and I stumbled across a possible solution to the slug problem that really seems to work – ducks! The idea arose from mere curiosity and also our background in Pemaculture. In 2010, Elizabeth and I moved to a rental house in the country and wanted poultry for our own egg production. We had witnessed the playful character of ducks at her brother (Ben Falk’s) homestead, and many of our friends had chickens, so we thought duck eggs would be a nice change. Additionally, when we have a ‘problem’, Permaculture teaches us to constantly see the opportunity in the challenge, a principle known as Problem = Solution. A pest or disease can be a symptom of a larger deficiency in the whole ecosystem, and co-founder Bill Mollison was fond of saying “you don’t have a slug problem, you have a duck deficiency.” I saw this concept in action in Scotland at the Findhorn Community Ecovillage, where they installed a small pond in their high tunnels to overwinter frogs, which happily browsed the greens for slugs and bugs.

That year, we decided to purchase two Indian Runner ducks at an auction and four Khaki Campbell ducklings, to have a total flock of six. By chance, and because it was close to the house, we fenced the ducks in the same location where I had set up a small shiitake log area. About halfway through the season, I realized I had yet to see a slug on the logs, mushrooms, or anywhere in the vicinity. It didn’t take long to figure out the likely reason why.


As we started planning our farm and homestead, we’ve always tried to go slow, introducing systems and observing how they fit into the landscape, farm system, and our lifestyle and personal enjoyment. When we start something new, we don’t commit it as hobby or commercial operation from the start, but rather start small. If economics, system integration, and personal enjoyment all work out, we assess and consider scaling up. Realizing that 6 ducks eradicated the slug pressure on the shiitakes made our dreams of farming 1000+ shiitake logs much more feasible.

In 2011, when we bought our land, the mushroom operation was expanding and we felt ready to increase our duck flock as well. We got interested in raising meat ducks for profit while also reducing the inevitable slug problems with the expanding mushroom enterprise. The main forested area of our farm is roughly 1-acre, composed almost entirely of sugar maple trees. Being relatively flat, in close proximity to Zone 0, and offering several established access routes make this forest an efficient maple syrup operation. But the maple trees provide more than just sap; their dense foliage means excellent shading during the hot summer months and a humid microclimate – perfect for both mushroom cultivation as well as habitat for ducks. Stacking sugar maples, shiitake logs, and ducks means that this 1-acre yields product from early February through late October. Additionally, the forest microclimate also supports a number of other forest farming crops we have begun to cultivate, including ginseng and a shade nursery.

As a permaculture teacher, I find that students are often very interested in the idea of multi-functional polycultures. (some call them guilds, but I avoid this as it confuses the term with its original meaning in ecology) As this maple-duck-mushroom polyculture emerged in our minds, we felt it was important to really test the concept and generate data and evidence to support any claims. Herein is a huge problem in the permaculture movement; there are many ideas and conceptual designs for polycultures, but little evidence that they actually achieve the claims of nutrient cycling, pest control, multiple yields, or any of the other theoretical benefits of multi-species assembly. As I teach, I am quick to point out that few polycultures have a research base, or even a long track record, of success. It’s easy to get excited about the idea, but if we are to be taken seriously by famers, academics, and skeptics, then better documentation is certainly needed.

The value of Research (and funding)

1.2_DuckswoodsIn an ideal world, farmers would add a new enterprise (like meat ducks) to their system with minimal personal investment and risk along with assurance they yields would meet a market demand. Crunching the numbers, we realized the cost to raise meat ducks was considerable; fencing, housing, brooding ducklings, and feed costs meant that we would need to commit over $5,000 to get started. Of course, we aren’t the first farm to run into this dilemma. Thankfully, the Northeast SARE farmer grant program exists in part for this exact purpose.[ii] The farmer grant encourages farmers to pose a research question, justify its importance, and request funding to find out the answer. We applied and were pleased to receive funding for two seasons in 2011.

In Year one (2012), we raised a total of 45 ducks of 4 breeds. In Year 2 (2013), we raised 2 breeds, 25 of each. In addition to their effect on slugs, we wanted to see which of the breeds were more effective at foraging and which would grow larger in size. We monitored the weight of the ducks, slug populations, and shiitake harvest quantity and learned a lot about the intricacies of managing a polyculture system. Our experiences with raising different breeds are documented in our report (see references).

Over two years, we found that (1) ducks were definitely effective in controlling the slugs, (2) We personally didn’t enjoy working with so many birds, and (3) that the number of ducks needed for slug control purposes and maintaining forest health does not match the number needed to make profit in duck meat sales. (We only needed 10 – 20 ducks for slug control purposes on our 1000 logs, but would need to raise 200 – 400 per season to make a profit from meat sales.) At that larger scale, we would expect to see a lot of impact on the forest and also felt like that many ducks would fundamentally change our relationship to them; turning them into only a commodity rather than also offering a “farm service”.

1.3_duckeggsThis was an important lesson and prompted us to change our approach and revisit our farm goals. It is ethically necessary for us to ensure the highest quality of life for our ducks, have quantities of animals that only positively impact the landscape, and try to avoid a system that’s a money pit. We realized that 20 egg ducks could provide our pest control needs and allow us to potentially break even on their costs. Duck eggs sell at a premium, $3.50 – $5 per half dozen, and our flock of 18 female Cayuga and Khaki Campbell’s lay 14-18 eggs/day during the long days of summer.

In 2014, we rotated this smaller flock through the maple woods and had almost NO slugs in our shiitake mushroom yard. There was one “outbreak,” during a very wet part of May, when the birds were in the pasture. One minor frustration is that we didn’t have a “control” plot this season (i.e. mushrooms fruiting but no ducks) to compare with our treatment (ducks) since the grant had expired. So while we had great results, we want to remain cautious. Five years of no slugs is much more significant than just one or two.
Here’s the break down of what works in our system:

1) Keep the flock small, and close to the fruiting area of the mushroom yard

2) Bring ducks into the fruiting area for periods of time, no longer than 1-2 weeks. Ideal timing is late spring, mid-summer and end-of summer.
We have found that leaving the ducks in one place for longer means some detrimental effect to the leaf litter in the forest. Plus, they do the job in a week or two and are ready for new forage.

3) Build a “duck moat” to effectively control slugs and encourage foraging
During the first year of the SARE research, we learned that some breeds of ducks would occasionally peck at mushrooms, thereby defeating the purpose of protecting these perfect specimens from slugs. We also realized that organic standards (we are not certified but do follow/exceed them as much as possible) were to ensure that fresh animal manure and produce didn’t mix; usually at least 90 days must elapse between manure “application” and harvest. For this reason, we circled the log fruiting area with one set of moveable netting, then added a larger ring of electric netting around this, leaving about ten to fifteen feet of space in between. Hence, the “moat”, where ducks happily did loops around the mushrooms and snatched up all slugs in sight.

4) Remember that the goal is to suppress the overall population – not pick slugs off of logs or mushrooms. If slugs have made it to your logs – it’s too late!

This point is important because it offers some flexibility in timing, and means that ducks can be moved throughout the farmscape to deal with a myriad of pest problems. We are still curious to figure out roughly how long we can do without duck pressure before the slugs show up again. It seemed to be somewhere around three or four weeks during this past season.
As part of the grant, we created a comprehensive document outlining our duck/slug/shiitake research. This PDF also contains our thoughts on basic duck care because we found a lack of comprehensive information on duck raising and wanted to fill some of the gaps for other interested farmers/homesteaders. The booklet can be downloaded for free at our farm website.[iii]

Economics of a maple-slug-mushroom polyculture

In addition to showing evidence that the system works, it’s been important also to look at the economic implications of our emerging polyculture. As shown in the table, we are making over $7000 in gross income per season off this one acre woodlot, with roughly $4,000 in expenses incurred during the season (not including infrastructure and establishment costs). $3,000 an acre in profit is quite good, and including in these expenses is paying ourselves a living wage for our time.

The bulk of this income is unquestionably from shiitake mushrooms, while the ducks are actually offering a loss, at first glance. If we consider however that the absence of ducks would mean a 10% loss in shiitake, this would mean a loss of about $500 from out profit. Further, we could easily spend 2 hours a week all season, another $400 in labor costs. So that $900 “loss” of the ducks is made up in our shiitake profits, and in savings from a decrease in labor for slug patrol. Further, it’s pretty easy to argue from a quality of life standard, that not having to pick slugs off logs is nearly priceless. It’s easily one of the worst jobs on the farm. The maple syrup is a whole other story; we value this crop as a valuable trade item, opting to mostly exchange it for meat, vegetables, and other products we don’t produce. Of course, maple syrup keeps for many years and can always also be sold, which buffers us with some resiliency. In our case, this system “breaks even” from an economic perspective.

This polyculture example offers some interesting insight. For one, not all individual enterprises need to be profitable, but the polyculture as a whole should be. It also follows that a polyculture offers strength in multiple income scales, and constructs. Having a crop that is the cash “cow” (shiitake), mixed with a support species (ducks), along with a valuable trade commodity (maple syrup) means that we are maximizing our capital from many forms; financial as well as social, and living capital.[iv]


Enterprise Shiitake Mushrooms

1000 logs

Duck Eggs

18 laying ducks

Maple Syrup

100 taps

2014 Income





316 lbs @ $11.25

217 lbs @ $12.00



TOTAL = $6,159

103 half dozen sold for $3.50/doz



TOTAL = $360.50

15 gallons produced, at $45/gal

TOTAL = $675

2014 Expenses (not including infrastructure, establishment costs)




Hired Help: $600

Materials: $500

Time: 6 hrs/week x $12 hr x 14 weeks = $1,008



TOTAL = $2108

Feed: 4 lbs/day @.30/lb = $1.20/day = $436.80/year


Labor: 5 hr/week X $12/hr = $840


TOTAL = $1276.80

Labor: 50 hrs x $12/hr = $600

Fuel: $100 (scrap)





TOTAL = $700

Profit/Loss + $4,051 – $916.30 – $25



Sold to restaurants, and to a CSA. Could easily produce more; not currently meeting demand Sold to co-op, butcher shop, and CSA members. Could easily produce more. Mostly used for barter in our local community; in the past we’ve traded for tinctures, meat, and veggies



To wrap up, we are really pleased at the success of this system – at least so far. We also keep finding new jobs for the ducks on the farm. Every few weeks throughout the summer, we put 3 or 4 of the ducks in the veggie garden for a few days. As long as plants aren’t really young, they tend to leave them alone and just forage in between. At the end of the season, we let the ducks camp out in the garden for weeks, as they munch on critters, fertilize, and clean-up from the season. In 2015, we also plan to rotate the ducks through our pasture prior to our sheep. There are two parasites that threaten sheep, which are spread through snails and slugs. We are hopeful we can minimize our sheep’s risks to these parasites if ducks are present to eat snails and slugs.

Steve Gabriel is an ecologist, author, and educator living in the Finger Lakes Region of New York. He recently co-authored a book, Farming the Woods, with Ken Mudge and works as agroforestry extension specialist for the Cornell Small Farms Program. He can be reached at


[i] offers support and resources for young and beginning farmers




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  1. Pingback: Mid-Atlantic Native Food Forest Polyculture for Rain Gardens & Wet Sites | Lunaria Gardens

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