Inoculation is the process by which we judge the resistance of a chestnut tree. There are three methods by which one can test the resistance of chestnuts, with the method generally being chosen based on the size and type of chestnuts being tested.


Small stem assay - Article from the Journal of the American Chestnut Foundation describing the process


Large stem assay - This is the most common technique for evaluation of moderately resistant chestnut trees. Please see below for more details on the process.

During the inoculation procedure, we take a plug of chestnut blight and insert it directly into the trunk of a chestnut tree.

The process of inoculation is highly dependent on weather. Keep your eye on this website for weather updates. If rain is forecast for an entire scheduled inoculation day, inoculations will be held the following day (see rain date); however, if it looks like the rain will be spotty, we'll wait until passing showers finish their business. Should the forecast call for extended periods of cold and rain following the inoculation day, likewise, inoculations will have to be postponed. Keep your fingers crossed for fair weather.

The following approach is used for larger chestnut trees. In general, we use these procedures in our backcross orchards, where the backcross trees will exhibit no-to-moderate resistance.

Before You Inoculate

1. Tree shelters must be removed summer before to allow trunks to harden to a natural condition.
2. Diameter at breast height or at top of tree shelter must be a minimum of 1.5". A larger diameter is preferred.
3. Early June is generally the time to inoculate.

Inoculate your orchard when the majority of the trees average 1.5" DBH or higher. Attempt to inoculate all trees in the same orchard at the same time in order to be able to select from an entire backcross line at once.

Supply list for Inoculating 150 trees
Inoculation Technique
Selection Procedures
Photos and Stories of Past Inoculation Events
Summary of Inoculation Lines (by orchard) - Excel

Excel spreadsheet, 103.5 KB

Small Stem Assay

PDF document, 497.4 KB