U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version


Document Type



Agricultural Research 61(7): August 2013; ISSN 0002-161X


Plant diseases must be managed to successfully and reliably produce crops to meet humanity’s growing food, fiber, feed, and fuel needs. Plant disease management relies on many different types of tools—from disease-resistant plant varieties and pesticides to cultural and biological strategies. Agricultural Research Service scientists are seeking new methods of managing plant diseases, more efficient means of using older methods, and combinations of these methods. Two of the oldest ways of reducing plant diseases are crop rotation and organic amendments to soil.

In Orono, Maine, for example, ARS scientists are evaluating a holistic approach to suppressing soilborne pathogens of potato, including 2- and 3-year rotations with barley, ryegrass, canola, and rapeseed. In one study, the regimen reduced the incidence of Rhizoctonia by as much as 50 percent. They also examined the effectiveness of biological soil amendments, such as compost tea (compost steeped in water) and cover crops of winter rye, against various types of scab, black scurf, and other potato diseases. (See story in the next issue.)

Historically, heat has been used to rid plants of some pathogens—at temperatures and durations that won’t damage the plants in the process. Indeed, in Fort Pierce, Florida, ARS researchers are evaluating such a method to rid citrus seedlings of the bacterial agent that causes Huanglongbing (HLB), also known as “citrus greening.” The citrus disease has caused serious economic losses in the “Sunshine State” and in other citrus-growing regions of the world for decades. The disease weakens, and can eventually kill, afflicted trees as well as render their fruit unmarketable.