On April 26, 2010 the field day How Herbicides Work
took place at the University of Arizona Yuma Agricultural Center. In this event Barry Tickes, UA Agriculture Agent and his students from the applied weed science class PLS 300 explained the different herbicide modes of action directly from the experimental plots. We are frequently so busy spraying our gardens and crops for weed control that we tend to forget how these products really work. By attending this meeting we have learned for example that the Seedling Root and Shoot Growth Inhibitors
kill weeds by affecting mitosis, the process in cell division by which the nucleus divides causing what is called "pruned roots" in the treated plants, this makes weeds suffer from lack of water and nutrients. The students showed us Epinasty
, a symptom caused by the Growth Regulators
and explained how the weeds turn white by the action of Pigment Inhibitors
. Tickes also showed the symptoms of an application of a Cell Membrane Disruptor
which have mostly contact activity. He explained that these herbicides produce a dark green water soaked appearance on the leaves, which means that the cell membranes were destroyed and there is leaking of intercellular fluids, which causes necrosis. Are you interested in learning more?
You can watch the videos on How Herbicides Work
by visiting the Vegetable IPM Video Archive located here: http://ag.arizona.edu/crops/vegetables/videos.html. This archive contains also videos on insect management, evaluation methods, and insecticide trials that are conducted by researchers at the University of Arizona Yuma Agricultural Center, and in the future will include plant pathology videos.