Are soybeans or tomatoes more sensitive to dicamba? Are sweet potatoes or watermelon more likely to be hurt by 2,4-D? Could crops show visual injury at 1/800th of the rate of one of these products?
In a recent article in Southeast Farm Press, Dr. Stanley Culpepper, University of Georgia Extension weed specialist, shared his data on crop sensitivity (visual injury) to dicamba and 2,4-D. Note that most of this data is from trials in Georgia (and some of the crops on the list reflect that).
Keep in mind, spray drift is not the only way a sensitive crop could be exposed to these herbicides. Residues in the sprayer, even after cleaning, can be enough to cause problems. See Sprayers101 for resources on sprayer cleaning. And don’t forget about the dangers of temperature inversions.
If, in your spraying career, you haven’t had any issues with off-target glyphosate damage, are you likely to have a problem with dicamba or 2,4-D?
Dr. Culpepper says that “some crops widely grown in Georgia are 10 to 20 times more sensitive to dicamba or 2,4-D” than they are to glyphosate. Judging by these visual sensitivity scales, the same could be the case for Ontario. The only thing we can be fairly sure of is that we won’t see significant dicamba or 2,4-D injury to cotton here in the forseeable future.
Thank you to Dr. Stanley Culpepper, University of Georgia Extension, for permission to reprint these graphics.