Improving yields of shiitake cultivation in the Northeast by selecting appropriate strains

View the project final report

• 2016 annual report

Commodities

• Miscellaneous: mushrooms

Practices

• Crop Production: forestry
• Education and Training: demonstration, extension, farmer to farmer, networking, on-farm/ranch research
• Farm Business Management: budgets/cost and returns
• Production Systems: permaculture, organic agriculture

Shiitake mushroom cultivation is expanding in the Northeast. According to projections in SARE Project ONE14-214 northeast shiitake log growers plan to expand from 17,968 bolts to 59,575 bolts by 2018. 100% of indoor growers who responded to our survey plan to expand shiitake production. The objective of this increased production is to meet demand for high quality locally produced shiitake mushrooms. This proposal aims to meet that goal by growing mushrooms more efficiently rather than increasing the amount of substrate used in cultivation. Through proper strain selection growers can increase the amount of mushrooms produced without increased investments. Many leaders in mushroom cultivation like Dr. John Holliday, Dr. Paul Stamets, and Dr Shu-Ting Chang emphasis strain selection as a critical first step in mushroom cultivation. Several researchers have tested shiitake strain yields, but most studies are outdated and no trial has been conducted in the northeast. This proposal will allow us to cultivate six strains of shiitake mushrooms on logs (outdoors) and sawdust blocks (indoors). The yields from each strain and substrate will be measured and information like morphology, storage, and disease resistance will be noted. The logs will take 2 ½ years to receive sufficient data while the sawdust will be completed in 6 months. This information will be submitted to the Mushroom Growers Newsletter, Commercial Mushroom Growers Network, Cornell Mushroom listserv, posted on our website, shared through our newsletter with over 600 people, and provided through 2 on farm workshops.

Objectives
We would like to have clear data trialing different strains using common cultivation methods for shiitake mushrooms. This project would give farmers the information to make decisions on what spawn to buy to maximize their investment of labor and resources. We aim to increase production of shiitake mushrooms in the northeast by suggesting the highest yielding strains. In each trial we will record yields for the six different strains and note differences in traits like morphology, storability, and resistance to disease. The substrates we will use are supplemented oak sawdust and oak logs. These are the two methods used by indoor and outdoor growers respectively.

Strain to strain yields will then be compared between the two substrates to see if differences in yields can correlated across substrates. This provide a precedent for future log growers and spawn producers to trial strains on sawdust, giving them data to adjust production methods within months rather than the years of trialing required for log cultivation.

Methods and measurements
Six shiitake strains will be grown on supplemented sawdust (SD) and logs and tested for yields, disease, morphology/mushroom quality, and storage life.

Strains will be selected based on popularity with indoor and outdoor growers as well as yield data. The six strains will be “3782”, “75”, “Straw”, “CS” “WR46”, and “Lambert 123”. The first four strains are high yielding strains from the Aloha study, WR46 was the highest yielding strain from Bruhn et al 2009 and Sabota 1996, and Lambert 123 is used in large scale indoor shiitake production. The first step will be acquisition of spawn from Aloha Medicinals and Field and Forest (spawn is the “seed” used to propagate mushrooms). Spawn will be outsourced rather than produced in-house in order to free up time for the log experiment. Once received spawn will be transferred to sawdust and then used to inoculate either logs or supplemented sawdust.

Supplemented sawdust will be formulated and sterilized using the method we use for commercial production. Briefly, hardwood sawdust, wheat bran, and gypsum will be mixed at a volume ratio of 100 gallons to 25 gallons to 1 gallon, then moistened to 50-60%. Sawdust will be loaded into filter bags in 5 lb aliquots called “blocks”. 20 blocks per strain will be made, for a total of 120 blocks. Final moisture content will be measured in order to calculate biological efficiency. Blocks will then be autoclave sterilized, inoculated with spawn under sterile conditions, and allowed to colonize for 3 months, or until fully browned. Weekly monitoring will be employed to characterize contamination rates, time until colonization, and time until maturity. Time until browning will determine suitability for cultivation on sawdust, as browning is an indicator for maturity. Once blocks are browned, they will be cold shocked at 37 degrees for 24 hours to initiate fruiting. The filter bags will be removed, and the blocks will be moved into the fruiting room. Fruiting will take place over the next two weeks. The total fresh weight for each strain (20 sawdust blocks) will be measured in to calculate biological efficiency (BE). The BE formula is B.E.= (fresh weight of mushrooms/ dry weight of substrate) * 100. (Chang et al 1981). In addition, differences in mushroom morphology, disease, and storage life between strains will be noted. The entire experiment will be repeated again two weeks later.

Logs will be harvested immediately before inoculation. Logs will be taken from ~6” diameter oak trees, and cut to 4 ft lengths. Any logs with evidence of fungal growth not be used. Inoculation will be performed by drilling ~50 5/8 inch holes per log using a shiitake drill, and filling them with sawdust spawn using palm inoculators. One sawdust block of a given strain will be used to inoculate 20 logs for a total of 120 logs. The holes will then be sealed with cheese wax to prevent moisture loss and contamination by other fungi. Logs will be stacked “log cabin style”, placed under shade cloth, and incubated until fruiting initiation. Fruiting will be initiated three times a year in 2017 and 2018: in late spring (Early June), summer (Early august) and fall (mid October). Initiation will be done by a 24 hr water soak, followed by propping logs on end to allow harvest. Logs will be harvested in the subsequent 2 weeks, after which they will be returned to “log cabin” stacks to rest until the next fruiting. In addition, logs will be monitored and harvested weekly from may through mid-november to catch naturally initiated fruitings. Yields will be recorded during every fruiting event and aggregated at the end of year 1 and year 2. Fresh weight rather than biological efficiency will be used as a measure of yield due to inconsistency between log moisture contents. In addition, mushroom morphology, disease, and storage life will be noted.
 

Fresh yield weights from logs and SD will be compared as a ratio in order to see if yield differences between strains can be correlated between substrates. Within substrate yields on SD and logs will be used to compare strains by using BE and fresh weight respectively. Further statistical analysis may be performed in order to determine if differences are significant.

Project timetable
The experiments in this project will take place between March 1 2016 and November 31 2018. See Table 1 for a year by year experiment outline. In addition to dates shown in the table logs will be checked weekly and harvested as needed to account for naturally initiated fruitings.

Outreach plan
This information will be submitted to the Mushroom Growers Newsletter, the Mushroom Growers Network of North America, posted on our website, shared through our newsletter with over 600 people, and provided through 2 on farm tours. The two tours will be provided during the project one in the second year and the second in the third year. We will demonstrate our procedures, discuss how we are recording data and report on our findings. When we have completed all research in 2018 we will present our data in easy to read tables with a short summary of our process and findings to the mentioned mushroom grower networks. We will also work with Umass, Vermont, and Cornell extension to help spread the word to interested parties.