Tuesday, February 12, 2019

Tips for Handling Mushroom Logs after Cutting

By Lindsey Bender

Growing Shiitake mushrooms on logs is a rewarding experience. Anyone harvesting their first flush of Shiitake in the spring will agree, (especially outdoors-deprived northerners after a long, cold winter 😊)  If you are planning on inoculating logs this spring, the following tips can help answer some questions you may have, plus, we share our newest research results concerning cutting and aging wood for shiitake logs. It's never too early to be thinking about mushroom wood!


  • Start with the best quality logs whenever possible. Most experienced growers know that the quality of the fresh cut log is crucial to spawn run success and mushroom yield, and it starts with the log as it is cut from the tree. We all know the importance of cutting healthy, living wood. If you are cutting softer hardwoods such as Silver or Red Maple, select stems that have thicker, rougher bark.

Thicker bark (left of center) Red Maple is preferable to thin bark (right of center).
  • Use best practices for storing the logs prior to inoculation. It turns out that certain wood species, due to their cell structure and bark characteristics, may prefer a longer seasoning time prior to inoculation (read next item below for more details). The longer "seasoning time" can positively influence overall mushroom yield.
  • Wood should "season" at least 2 weeks before planting; longer for some wood species. Historically, the rule of the thumb has been "fresh is best," when it comes to deciding how long logs can sit after cutting before inoculation. Why? These very fresh logs are free of contamination because the living tree was warding off invasion of weed fungi. Fresh cut logs have abundant moisture, but must start to loose some of the free water before inoculation. Allowing logs too little time to season can result in a lag time in spawn run after inoculation. Spawn must wait for the log to start drying so the log can be hospitable to fungal growth. Trees have differing moisture contents by species, age and environment, but across the board it is moisture loss, the key factor in determining if wood is inoculation-ready, that suggests that the logs cure for AT LEAST 2 WEEKS prior to inoculation. This time allows for the free moisture in the log to be released but holds in the bound moisture, necessary for Shiitake growth.   

Log with sprout (center of the stack) suggests lack of cure time prior to inoculation -
notice lag in spawn run (no white mycelium on log end).
  • A 2 week cure period may not be long enough for some logs – especially in Red Maple (and probably most other maples). Over the years we've followed the 2 week resting rule across the board in our harvested logs, regardless of wood type, but noticed remarkable yield difference in Red Maple logs rested for 2 weeks compared to several months of rest. We decided to take a closer look, and to see if the same trend was also true for Sugar Maple, a related species.

Cure Red Maple a few months prior to inoculation, even if the bark is thinner than you would like.
  • The longest rest time in both the Sugar Maple and Red Maple in our study resulted in the highest yielding shiitake logs. In 2016/2017 we harvested Sugar Maple logs which were divided into two groups, one inoculated 1 month after cutting, and the other 6 months after cutting. Similarly, Red Maple logs were divided into two groups and were inoculated either 1 month or 5 months after cutting. All logs were incubated together under the same conditions then force fruited the following year to collect Shiitake yield information. Logs with the longest rest time prior to inoculation in both the Sugar Maple and the Red Maple proved to be the highest yielding Shiitake logs. Based on the results of this study, longer rest times for Red and Sugar Maple logs can increase spawn run success and overall Shiitake mushroom yields. Keep in mind that this study was conducted in northern Wisconsin where temperatures are cold and logs are covered in snow during seasoning. Logs cut in the south will dry faster and season quicker, so the 5 month time will likely be too long for those areas. 



  • Protect your logs if you wait to inoculate. There are caveats to longer rest times. Below is a list of risks and how to manage them: 
  • Losing log moisture Store your logs properly in the shade, out of the sun and the wind to reduce this risk. Especially with thin barked trees like Red Maple, take care to minimize moisture loss over a longer storage period. Felling and leaving the tree whole and cutting it up just prior to inoculation is a good strategy for long months of curing, especially in snowy areas. Stacking logs on a buildings' north side also helps. You may dead stack them and cover them loosely with a breathable cloth to allow penetration of rain and snow. Before inoculating, check the ends of the logs for cracks. Small cracks are okay. If the cracks are wider than the width of a dime, then soak your logs in water for 12-24 hours prior to inoculation. 

Logs awaiting inoculation are dead stacked on limb wood rails to minimize soil contact.
  • Contamination: If logs are cut into lengths prior to curing, store them off the ground, elevated slightly by rails or a pallet to avoid soil contact. Avoid consistently wet bark by tarping logs as they rest if you have weeks of continuous rainy weather. 

We wish you a spring season with mushroom-loaded Shiitake logs!


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5 comments:

  1. I wonder if there is any data on this beyond an increased initial flush... Waiting longer to inoculate, does it lead to a healthier log in the long run? Total yield information on this approach? Fast initial fruiting is nice, but for a lot of folks it is the total yield that is most important.
    Thanks so much for sharing this research and for all the work you folks do! Kudos!

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    1. Hello! Those are excellent questions you pose and certainly something we plan to answer with actual data in several fruiting seasons! We have these logs segregated in our experimental yard and will be following shiitake yield over their life to determine whether the initial results are supported.

      We suspect that rest time is most important in determining spawn run speed and success. What we can say is that if spawn run is hindered (whether due to insufficient rest time or other variables), the log will colonize slower and result in delayed fruiting, or possibly none at all. Once spawn run is complete, however, the potential yield from each log is more based on the quality (wood type, log size, bark, moisture content, etc) of the log. Because of this, we suspect that as long as the logs had successful spawn run, they should result in total yields typical for the quality of the log overall regardless of spawn run speed.

      Stay tuned for the final results!

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  2. Hi, I will start an experiment with oyster and shiitake in logs. I wonder if you have any experience, or if do you know someone that has tried this in the tropics. I live in Colombia and will try this in a site close to Bogotá and 1700 meters over the sea level. This is a very humid and forested site. Any advice will be very appreciated to start my small experiment. Thanks a lot. Lorena Franco

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    Replies
    1. Hi Lorena, thank you for your interest in growing! Yes, it sounds as though your area has the humidity to support outdoor mushroom growing. For strains, we would recommend trying some of the warm temperature fruiting varieties such as the Golden, Summer White or PoHu oyster varieties. West Wind and Night Velvet would be our recommended shiitake varieties. Be sure to use ideal wood types for growing both the oyster and the shiitake as the heat and humidity in your climate means your logs will mature quickly. Please feel free to contact us at info@fieldforest.net if you have any more questions!

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  3. Hello, I'm planning to inoculate some sweet gum logs. I'm confused because many sites recommend to inoculate immediately after cutting, specifically for sweet gum. I'm going to experiment both ways. I have some logs that were cut two weeks ago that I'll soak and use. Then I'll cut some fresh logs and inoculate immediately. I am brand new to this and would appreciate any thoughts or advice. My location is central South Carolina. Really enjoying your blog, btw, I'm about half done with reading it all.

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