Breeding for pest resistance requires the same basic steps taken to develop other traits. A critical step is to expose the new plant to the pest to make sure it exhibits the resistance along with the other desired traits. Living things can perform differently in different environments. So the breeder needs to be sure the screening for pest resistance is done where the pest is active and where the correct variant of the pest is present. If, for instance, you try to screen grapes for black rot resistance in a dry environment, the results won't mean much because the fungus needs a certain amount of tissue surface wetness to germinate the spores and infect the plant.
Pests vary also, in time overcoming resistance.
Gardeners should know that desirable traits introduced into plants are not guaranteed forever. John R. Clark, a professor of horticulture at the University of Arkansas, teaches plant breeding. Used by permission. Read our Privacy Policy .