Herbicide on Pecan Production

Pecan trees in south Georgia growing in rows immediately adjacent to peanut fields and highway right-of-ways developed hollow pecans. In-shell nut size and appearance was normal. However, the kernels failed to develop. Because both peanut fields and highway right-of-ways are commonly treated with the herbicide imazapic, this chemical was suspected as a potential cause of the problem. UGA horticulturists conducted replicated studies at a UGA pecan research orchard to evaluate the effects of imazapic on pecan from 2008 to 2009. Pecan kernel filling was significantly affected by soil application of imazapic in both years of study. This research demonstrates that imazapic can be absorbed by pecan roots, resulting in inhibition of kernel development and shuck split. As a result, precautions should be observed with the use of imazapic near pecan trees, particularly on soils with a heavy clay content.