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Summary Results for Establishing Natural Controls of Competitive Fungi in the Production of Shiitake Mushrooms


SARE Grant FS06-200


January 2008


Problem:  I have experienced that competitive fungi has been a major hindrance in establishing fruiting cycles and preserving the full use of a cultured log. Competitive fungus infections have been one of the major causes for my shiitake farm failures.


Solving the problem: This experiment has been useful in finding a working solution. Each station yielded results in helping me understand environmental parameters for fungus life cycles. The following is a collection of results, things that I observed and facts that I have learned.


If disease fungi infect a shiitake log before the shiitake spawn has become established, the fungi can kill the spawn before it can grow into the log. I have learned if you have an infection problem within the first six months of inoculation, you should identify the infection, learn the life parameters, separate from non infected logs and make adjustments to solve the problem. Failure to do so will result in loss of the shiitake log.

My logs were showing signs of infections within the first three months after inoculation.


 The infection was identified as trichoderma. Trichoderma first appeared on the sealing wax of the drilled inoculated holes. It appeared as a green looking mold, later forming a white ring around the wax and over time the spawn would rot in the drilled holes, the underlining of the bark on the logs would then rot, began to crack or fall off, thus destroying the shiitake mycelium. The destroyed bark would make way for other fungi to infect and feed on the log. The end result is a log that does not produce or is short lived in producing the shiitake mushroom.





Above you can see in the upper left corner trichoderma infection  (the white ring) and on the right the gray scale on the bark   is a diatrype infection.





                                         A trichoderma infection




I learned that trichoderma likes high humidity’s, no air circulation; it can survive in a wooded or field environment. You will find these spores to be present indoors as well as outdoors.  A 10% bleach solution for one minute will disinfect and kill the spores. The logs that were inoculated for this project and the years before this project were inoculated and temporary stored in my mushroom house. Most likely the cause of my log infections; the mushroom house had high humidity and poor air circulation. The logs were inoculated during the winter months so there wasn’t any outside air being forced into the house. The groups that were set up for this project also support the cause for trichoderma infections. In all sections where the logs were kept covered in the first six months; the majority of logs were lost to trichoderma. The covered groups were breeding grounds for trichoderma. I first discovered the trichoderma infections when I was setting up the different test sections. At the time I didn’t know how to handle the infection and had no solid advice on treatment. I altered the project to include these infected logs to see if I could find a treatment solution for the infection. This is when I discovered that soaking the logs in a bleach solution for a few minutes would help control the infection. The majority of the logs that were treated in bleach and not covered came to be productive logs in their group. Most of the covered logs were lost.


In the Field or in the Woods?  I would say that if you have a woodland area, use it, and store your logs there. The logs in the field area did ok. The draw back from the field area is the expense of setting up a shaded area, and extra water usage. The logs in that area had a tendency of drying. Competitor fungi polypores or bracket fungi were common on these logs. These fungi’s are a sign that the log has been kept to dry.


Did the different groups make a difference? YES! Group “A”:  This group was the first to produce a mushroom, this group only lost 6% of it logs to other fungi’s during this test period, and this group had the highest production on mushrooms coming out of the 2007 summer drought. With this said the overall conditions of the logs was in fair shape; (on a scale of 1 to 5, 5 being excellent I would give it a 3). This rating was given because signs of trichoderma had rotted a portion of inoculated holes, some bark has fallen off, and secondary rot cycles are present on the logs that have come into contact with the ground.  Group “C”:  I would say this set up is a bad way to go. More than 50% of the logs were non producers during the test period. The logs that did produce mushrooms, the amount that was produced was minimal. There is also much more labor in trying to stack the logs. What I did observe about this group that could be useful in a shiitake operation was other fungi didn’t do well either. I would say the kenneling effect would be the reason. Because of this, this might be a good way to temporary store freshly cut logs before they get inoculated. Group “E”: I would say this is a bad way to go as well. More than 50% loss of the logs, this group also had a high level of trichoderma infections, bark in very poor shape. I prefer this set up for fruiting only. Group “G”:  This group was a good log keeper. The lost was at 4%, the overall condition of the logs was good. a scale rating of 4. There were some bracket fungi present; much less signs of trichoderma infections compared to group “A”, mushroom production were less than group “A” but better than the other groups. The kenneling effect is a concern because signs of drying; with the bottom of the log in contact with the ground this gave the extra moister group “C” didn’t have. The groups that were placed in the field area had comparable outcomes to the groups in the wooded area. Group “I” had the best outcome with a 10% loss. This group was not treated with bleach but it didn’t have any signs of trichoderma infections when setting up the test station. The group now shows a fair amount of trichoderma infections and the logs that have laid on the ground have secondary rot fungi. Groups “M” and “O” faired about the same. These groups were treated with bleach. The logs condition is in fair shape with bracket fungi more present than compared to the wooded groups.


When do you determine an inoculated log is bad? The standard I set for this project is if another fungi is present on the log up to 25% of the log, identify the fungi, learn what it takes to make it thrive and make environmental changes that would slow or stop the growth but not harm the environmental requirements for the shiitake mycelium. If another fungi growth is more than 50% of the log remove and isolate, more than 75% of the log, remove and destroy. I have learned that shiitake can thrive on a log with other fungi growths but usually with smaller fruiting amounts. I have also learned to be very patient with logs that do not fruit when others in its group do. In every test group I had logs that I had marked as non fruiters that fruited shiitake 18 months from the time when the log was inoculated. As long as the log is not showing signs of other fungi infections, mark it, keep it, and track it. All logs that did not produce shiitake at the close of this project were destroyed.


 My Plan of Action:  First, my freshly cut logs to be inoculated will be stored as the logs in group “C” with some modifications, I will lay ground cover down,  using blocks and lumber I will build a rack to stack my logs on so the bottom logs will be off the ground. I will also keep the height of the stacked logs to about three feet to reduce the kenneling effect. A day or two before I inoculate the logs I will soak them in tank of fresh water to rehydrate them. Second, at the time of inoculation I will do so out doors separate from the resting yard. Once the wax has sealed and dried over the inoculated holes I will dip the logs in a 10% bleach solution for 1 minute, (this step is a maybe). Third, I will create a new resting yard for the logs. The logs will then be placed in rack as in group “G”. During the incubation stage of the mycelium, if the summer months become very hot and dry I will transfer them to a resting stage as in group “A”. The amount of watering and soaking I will do to logs will be determined by the amount rain, temperatures, cracking on the endings of the logs, and other fungi growths. I will most likely follow my good log/bad log rules until someone convinces me other wise. I will continue to use the mushroom house for fruiting only.





Details matter:  Be alert, pay attention to the conditions of the logs from the first stage of inoculation to fruiting the log, storing the log in the resting stage. I have learned that keeping records of fruiting times and amounts will help you make growing choices, keeping track of labor hours and expenses will help you to determine a fair market value. Keeping an activity log book will help you remember small changes that you might make along the way that you can reflect on in good and bad times, what environmental conditions were like when production was at its best, and help you determine the amount of logs you might want to force fruit to meet production requirements.


Future test projects:  I think it would be worth while to have test stations that would monitor this plan of action along with comparable groups of logs that were treated with a bleach solution after inoculation compared to logs that were not treated to see if this step helps or harms the shiitake mycelium in becoming established in the log. It would also be worth while to compare watering cycles to production amounts; such as: once a group of logs has been inoculated, soak one group once a month another group every other month and another group once every three months regardless of rain and temperatures. This would help to determine the amount of labor you put into log maintenance verses production amounts. This information would be very important to having a successful farm.


Conclusion: Our communities need strong diversified farms than can supply a variety of nutrious fresh food to the local market. I believe that shiitake mushroom farming can be adopted into a vegetable farm operation. This would help the farmers to promote local food diversity with the use of sustainable organic agricultural practices. This project has been a help to me and I hope that it can be a help to others as well.




                                                                                                     James D. Day


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