|Our logs have been fortunate to have received consistent rainfall this summer. For those whose logs haven't....read on...|
With spring shiitake bed log inoculation behind us, we now turn our attention on the farm to outdoor mushroom production and bed log management of those freshly inoculated logs.
Here at Field & Forest Products, we inoculate logs with shiitake spawn twice a year. Our spring inoculation is generally 250 to 300 logs while our fall inoculation is around 1000 logs. Both require different water management schemes after inoculation because of their very different post inoculation resting spots. Our spring inoculated logs are moved directly into the woods, or laying yard, after inoculation. Our fall inoculated logs are moved directly into an warm and humidified incubation room indoors for the winter. These fall inoculated logs are dead stacked, tarped, and ignored for the next few months (moisture management of shiitake bed logs indoors is more complex and will be discussed in a later blog as we continue to develop a protocol based on work done in Japan). However, the spring inoculated logs that are placed directly outdoors require a little more early attention.
With outdoor incubation, we depend on regular rainfall and the proper log stacking procedure to maintain log moisture content early on. Most problems in the fruiting cycle of mushroom cultivation are linked back to the initial spawn run phase, so it pays to give the inoculation and spawn run year lots of attention.
This year we have been extremely fortunate that we have had adequate rainfall so far (knock on wood). But let's assume the natural water faucet gets turned off for an extended period of time and our green lawn turns to brown and that leafy debris in the woodlot starts to turn crunchy underfoot. This usually precedes a call to action.
We were once told the three most important things to remember in shiitake cultivation were 1) moisture 2) moisture and 3) moisture. You get the picture; fungi need moisture in the wood in order to digest it, and if the rain isn't falling, we will need to take corrective action. This usually means irrigation. We like to see a rainfall event on our logs at least once a week that amounts to at least an inch, and if we don't see rain in a week or two, either we leave the car windows open overnight or hang the laundry out to dry. If that doesn't do it, the sprinklers are turned on. We have a rather sophisticated system consisting of an impact sprinkler and a long length of hose. When called for we will turn the sprinkler on late in the day and let it run for several hours or long enough to fill a coffee can with about an inch of water (or overnight if we forget about it). We will not water again until a lack of precipitation dictates us to.
A general rule to remember is this: It is best to irrigate heavily and infrequently than lightly and frequently. The reasoning is this: With heavy, long irrigation cycles, water is able to move into the bed logs through the butt ends and somewhat through the bark (That's why we don't recommend waxing log ends!). When the water is turned off the log surfaces can dry and contamination by surface molds is minimized. With light, frequent irrigation, water never really gets a chance to penetrate into the log and log surfaces never really dry out so contamination by undesirables can become a problem.
The most important time for water management in bed logs is during their first growing season as the spawn establishes itself in the log. Once spawn run is complete, by the end of the growing season there should be no further need to irrigate. Mushroom production will benefit from a slight dry-down of the bed log as rainfall coupled with a cool-down in temperatures mimics the approach of a typhoon in shiitakes natural range, thus stimulating mushroom production. For information on soaking logs, see the most recent issue of our newsletter Mycologically Speaking... (If you are not on our newsletter email list and would like to receive our quarterly newsletter, you can sign up here).
What if you don't have irrigation capabilities? First and foremost is your choice of stacking methods that will promote spawn run and slow down log drying rates. Imagine a line drawn from northeastern
Florida to northwestern Minnesota and think about the different growing zones you would pass through. In the summer I imagine Florida to be warm and humid during the day and night with people sleeping in air conditioned comfort. In Minnesota, sometimes the summer nights require the winter quilt and a fire in the kitchen stove. Air conditioning? What's that? Along that line we can also measure log drying rates. In the warm and humid Southeast, drying rates are slow, while in cool and dry Minnesota, drying rates will be considerably faster. The Southeast has a more forgiving climate for shiitake log-based cultivation due to its warmth and high humidity levels during the growing season. In the northwest, the wrong log stacking configuration could lead to the production of some pretty darn expensive firewood. So one can also imagine now, along that line as one would leave the humid southeast and travel to the northwest, ever decreasing log stack heights. Of course this is a very simplified explanation as local environment will also influence log stacking configurations but the general idea remains the same. The dryer the site, the lower the log elevation during incubation. By the way, consider placing your smallest logs in the stack on the bottom and largest on top. Your small logs should dry at an equal rate as the large logs this way. Right now with summer temperatures rarely reaching 80F so far in northern Wisconsin, we have our logs lying horizontal in a single layer and the winter quilts have been used quite a bit this summer.
|These logs are too far from the sprinkler in this relatively open laying yard to benefit from supplemental watering so are stacked fairly low to the ground to take advantage of low wind speed and forest floor humidity during spawn run.|
Small diameter logs will dry out faster than large diameter logs, so soak those first. If the logs float, (We hope not!) weigh them down with concrete blocks, tractor wheel weights or some other hefty item. Several hours should be adequate to get water into the log. Do not be tempted to soak the logs longer than 24 hours as this could lead to anaerobic conditions within the log.
Do not attempt to soak logs for re hydration purposes after 4 months of spawn run have occurred. Sometimes a soak can bring on a premature effort to fruit which can weaken the running mycelium and thus overall log health. Sprinkling is a far better alternative at later stages of spawn growth.
|Containers that keep moisture out should also keep moisture in! This Minnesotan's canoe will moisten logs for spawn run as well as for forced fruiting later on. (Photo courtesy of Eagle Bluff Environmental Leaning Center)|
|Ozark Mushrooms in Missouri stacks logs outdoors in a shaded structure and irrigates regularly with a timed overhead watering system to keep log moisture content up.|
Something you can do to be more exact about assessing the moisture content of your logs is to establish a base line before you start any of this. This would be done by establishing "check" logs where the initial log moisture content has been predetermined. (By doing this you may find out that you don't need to soak logs after all.) This fairly detailed method is described in full here.
|Look for signs of spawn run at the log ends a few weeks after inoculation or once daytime temperatures are in the 70s (F).|