The saga over the genetically modified American chestnut tree just got more complicated. The American Chestnut Foundation, the leading group that has been trying to resurrect the iconic species through cross-breeding, has never been crazy about the genetically modified version known as Darling 28 created by SUNY researchers, but they have seemed willing to not block efforts to get the EPA and USDA allow it to be planted in the wild. (See my story from October here.)

On Friday, however, the group released a press statement saying it is “withdrawing its support for several pending regulatory petitions that would authorize distribution of transgenic Darling trees outside permitted research plots” because they aren’t working well. From the release:

Throughout 2023, TACF and its partners observed disappointing performance results from broad scale field and greenhouse tests of advanced-generation Darling trees across several different geographic locations at external testing facilities. As discussed in the September 15, 2023 episode of the Foundation’s webinar series, Chestnut Chat, analysis indicated striking variability in Darling trees’ blight tolerance, significant losses in growth competitiveness, and increased mortality.

Extensive ecological and other testing has demonstrated that the prototype trees do not present plant pest risks different from native chestnuts. “We are following best possible scientific practices and are confident this path will yield safe and effective restoration trees. While Darling trees would not adversely affect the natural environment, it is our assessment that these trees would impair future deployment of disease-resistant American chestnut populations,” says Sara Fern Fitzsimmons, TACF’s Chief Conservation Officer.

Next week, TACF will host several virtual events for our members and the general public to answer further questions. TACF’s staff and the Board of Directors remain optimistic about the long-term success of our restoration plan. With patience and perseverance of the best science, we will get disease-resistant American chestnut trees to forest managers and landowners.

This is disappointing. I have high hopes for the GMO tree, which seemed to sidestep all the problems with genetically modified organisms by using a gene found in lots of other local plants and creating a mechanism (blocking an acid that harms trees) which would not pressure the blight to evolve.