Glyphosate injury linked to apple tree collapsing?
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
In the last several years, there has been increased concern about insurgence of apple tree collapsing caused by Botryosphaeria sp. Cornell’s Dave Rosenberger talked about it several years ago at one of our MSUE fruit schools. Since then, disease symptoms have become more common in our orchards, particularly in McIntosh and Honeycrisp blocks. There has been a suspicion that glyphosate (RoundUp™) applications were responsible for the initial injury that led to fungal invasion and lesion development and tree collapsing. We have had confirmed Botryosphaeria sp. problems in a few apple orchards in the Hart/Shelby area in the last three to four years. There is an excellent article in Cornell’s Scaffolds Journal from August 2, 2010, Volume 19, No. 20 addressing this very same issue.
In addition to potential influence on disease development, in the article Potential non-target effects of glyphosate on apples, Dave Rosenberger is citing research done at Ohio State that has shown even low rates of glyphosate delivered to trunks of field-grown ornamentals can cause reduced winter hardiness and induce bark cracking in several ornamental trees including crabapple (Daniels et al. 2009; also see http://www.ag.ohio-state.edu/~news/story.php?id=4685)