Truffles

As the truffle industry in North Carolina (and North America, in general) is growing, there has become a need to more fully understand how to produce truffles in this region. The first step is to understand the level of persistence of the truffle on roots. As a response to the need for a testing service, we are providing a service to test roots and soil for the presence of selected species of Tuber. For any testing, please contact Inga Meadows (inga_meadows@ncsu.edu) before you sample and ship.

There are three different types of testing we can do:


1. Evaluate truffles for identification

Pieces (approx. 1 cm x 1 cm x 1 cm) of each truffle to be used for inoculation should be removed using a clean, sharp knife and each sample and air-dried at room temperature. Please place each piece to be tested its own container (plastic or paper bag is fine) so you can match results. We can test for Tuber melanosporum, T. aestivum, T. brumale, T. borchii, T. canaliculatum, T.  lyonii and other species upon request. This test can be conducted at any time of year.

There are two ways to prepare and ship: The simplest and cheapest is to air-dry the pieces at room temperature. Ship them in sealed, labeled plastic bags (one sample should reflect one truffle). You do not need to expedite shipping. Ground transportation (or USPS) is ok since they are dehydrated. The other option is to immediately freeze truffle pieces in labeled plastic bags. Use dry ice to ship the frozen pieces overnight to avoid secondary organisms colonizing the tissue.

Cost for truffle testing (option 1): $200 (up to ten truffles; $20 per additional truffle)

Results expected within 10 business days. Please note that if the species-specific assays are negative, extra time may be required to determine the species present. We will send samples off-site to sequence informative regions of DNA and this can take several days.

Click here for truffle testing SAMPLE FORM


2. Evaluate Tuber species colonization on roots and soil from inoculated tree seedlings.

If you are sending inoculated tree seedlings, please remove the top part leaving the root ball intact and place each sample in a sealed plastic bag with soil/potting medium. A minimum of 5 trees per 1,000 trees should be tested. If the lot is less than 1,000 trees, a minimum of 5 should be tested.

For assay 2, we test roots for the presence of Tuber species using an assay that can detect the DNA of Tuber species on root tips and soil/potting media (if T. melanosporum or T. aestivum). We also examine roots microscopically to count the number of root tips (as a percentage) that resemble Tuber species.

We can evaluate tree seedlings that have been inoculated with: T. melanosporum, T. aestivum, T. brumale, T. borchii, T. lyonii, and T. canaliculatum.

We also test samples for presence of contaminating Tuber species T. brumale and  T. indicum, when appropriate. Keep in mind that a negative detection does not mean the samples are free of these species, but that we were not able to detect them. We cannot prove these species are not present.

Cost for option 2: $110 per sample.

Results expected within 15 business days. Please note that if the species-specific assays are negative, extra time may be required to determine the species present. We will send samples off-site to sequence informative regions of DNA and this can take several days.

Click here for truffle testing SAMPLE FORM


3. Evaluate Tuber species colonization on roots and soil from an existing orchard.

For assay 3, we test roots for the presence of Tuber species using an assay that can detect the presence of Tuber species on roots and quantify the amount of mycelium i n soil of T. melanosporum or T. aestivum only. We also examine roots microscopically to be sure root tips resemble Tuber species and we use DNA markers to test individual root tips.

We can evaluate tree seedlings that have been inoculated with: T. melanosporum, T. aestivum, T. brumale, T. borchii, T. lyonii, and T. canaliculatum. We also test samples for presence of contaminating Tuber species T. brumale and  T. indicum, when appropriate. Keep in mind that a negative detection does not mean the samples are free of these species, but that we were not able to detect them. We cannot prove these species are not present.

Based on information from Europe, we suggest sampling roots from existing orchards towards the middle of the growing season because the mycorrhizal association is most active when the trees are actively growing. In the eastern US, this is usually around June to August.

Please note that if the species-specific assays are negative, extra time may be required to determine the species present. We will send samples off-site to sequence informative regions of DNA and this can take several days.

If we suspect root colonization by other mycorrhiza, we may be able to provide additional services to determine the identity of the competing fungi, if requested by the grower, for an additional fee.

Cost for option 2: $110 per sample.

Results expected in October through December (updated 12/19/2022): Because the time of year that is best to sample orchards conflicts with the busiest time of year for our lab group, we will only test received root and soil samples from existing orchards in Oct-Dec. You are encouraged to continue to send them immediately after sampling (in mid-summer) and we will preserve the root tips and soil appropriately, but we cannot promise results until Oct through Dec. Samples will be processed in the order in which received. We recognize that growers may be anxious to get results; however, experienced producers have confirmed that any management actions based on these results will not likely occur until late winter or early spring and that this delay in processing will not interfere with management actions.

Click here for INSTRUCTIONS to sample roots and soil from an existing orchard.

Click here for an EXAMPLE truffiére map (Prepared by Leo Stefanile)

Click here for truffle testing SAMPLE FORM


If you plan to collect samples, please email or call Inga Meadows before you collect to ensure the timing is appropriate (inga_meadows@ncsu.edu OR 828-456-3943).

It is best to ship samples so that they arrive at the lab Mon-Fri (avoid Saturday delivery as our lab is closed on weekends). If you collect late in the week, keep your samples in the fridge until you can ship them.

Update as of 1-20-2022. We no longer need to include the APHIS permit (described below) because APHIS has determined that “these species are not known to be plant pests or biocontrol organisms of plant pests” and do not require a permit. If you prefer documentation on this decision, please contact Inga (inga_meadows@ncsu.edu).

Ship to:

Inga Meadows

265 Test Farm Road

Waynesville, NC 28786

 

Root tips colonized by Tuber melanosporum (Photo by Kelly Gaskill)
Ectomycorrhizal root tips (not Tuber melanosporum) (Photo by Kelly Gaskill)
Ectomycorrhizal root tips (not Tuber melanosporum) (Photo by Kelly Gaskill)
Root tips colonized by Scleroderma sp.
Root tips colonized by Scleroderma sp. (Photo by Kelly Gaskill)