Bacterial diseases of plants are notoriously difficult to control and often result in sudden, devastating financial losses to farmers. Unfortunately, just as the emergence of antibiotic resistance sullied the miracle in clinical settings, resistance has also limited the value of antibiotics in crop protection. In recent years, antibiotic use on plants, and in particular the potential impact of this practice on human health, has been fiercely debated in several countries. This article will focus primarily on the situation in the United States, where I have been best able to access antibiotic use data and research reports. The diversity and quantity of antibiotics used for plant disease control is meager compared to medical and veterinary uses.
Tree fruits account for the majority of antibiotic use on plants in the United States.
Surveys have not revealed oxytetracycline resistance in plant pathogenic bacteria but have identified tetracycline-resistance determinants in nonpathogenic orchard bacteria. The genes strA and strB usually reside on mobile genetic elements and have been identified in at least 17 environmental and clinical bacteria populating diverse niches. Because antibiotics are among the most expensive pesticides used by fruit and vegetable growers, and because their biological efficacy is limited, many growers use weather-based disease prediction systems to ensure that antibiotics are applied only when they are likely to be most effective. Despite these efforts to reduce growers' dependency on antibiotics, these chemicals remain an integral part of disease management, especially for apple and pear production. Antibiotic use on crops and ornamental plants in the U.S. is regulated by the Environmental Protection Agency.