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Plants Under Stress

HAVE you noticed that some plants suddenly become infested with insect pests or just sicken and die? No doubt you concluded that they were mishandled somehow, perhaps being overwatered, or that some disease or possibly air pollution killed them. But were you aware of the fact that these harmful things put plants under stress? Yes, and that even before these plants showed any visible signs of having problems, they were quietly sending out “distress signals”?

This is what Charles B. Forney reported in the Easton, Pennsylvania, newspaper The Express. According to his column, Farm/​garden, “the United States Department of Agriculture reports some scientists claim plants tell us when they are under stress​—a warning signal.” These “scientists think they have found how a plant cries for help.”

It appears that when plants come under stress, they give off ethylene gas. Insects seem to be aware of these gaseous emissions. Sick trees that give off ethylene soon become the targets of voracious bark beetles. These researchers hope that by using a gas chromatograph​—a device that separates various gas emissions—​they can measure how much ethylene plants give off. Thus they can determine when a plant is under stress and if it is holding up under it. Obviously, just like humans, plants need to be protected against undue stress!