Plant diseases are often a major yield-limiting factor to many crops grown in the Panhandle. So it is important for these diseases to be properly and rapidly identified, so farmers can implement control measures.
Robert M. Harveson, Extension Plant Pathologist began a service in 1999 after arriving at the UNL Panhandle Research and Extension Center with the purpose of identifying disease problems, from samples submitted to the plant pathology lab at the Center.
Western Sugar initially provided partial funding for the diagnostic lab, because, in the first several years, about 75 percent of the samples submitted were from sugarbeet for diagnosing diseases such as rhizomania, Cercospora leaf spot, and Rhizoctonia and Aphanomyces root rots. In 2000, the diagnostic service was expanded to include any crop or plant species brought in to the lab.
Over the years the types of samples have varied. In addition to plant leaves, stems or roots, we have also tested soil samples for various diseases, beginning with rhizomania, a devastating virus disease that was transmitted to plant roots by a soil-borne fungus.
The center planted sugarbeet seeds into soil samples that had been collected from fields where sugarbeets were to be planted the following season and grew them for about 2 months in the greenhouse. After this period of incubation, they tested the roots for the presence of the virus pathogen. In 2003-04 the concept was expanded to include pre-plant disease index samples aimed at identifying the fungal root pathogens present in the soils, and to estimate the potential for disease problems the following season.
Both soil tests were designed to provide growers with some idea of what type of disease problems they might encounter, giving them the opportunity to make management decisions before planting.
As of December 2018, the lab has tested 3,886 disease index and 2,561 rhizomania soil samples, for a total of 6,447 soil samples. These samples, combined with all the plant stem, root, and leaf samples from growers, consultants, research colleagues, homeowners, and numerous disease surveys, add up to well over 27,000 total samples received into the plant pathology lab and processed. These disease diagnostics have helped establish and advance the direction of the research and extension program.
The diagnostic service has emphasized sugar beet root rots, bacterial diseases of dry beans, and sunflower diseases. But we have also detected and studied dozens of additional diseases from 65 to 70 different crops and plant species, including Aphanomyces root rot and dry rot canker of sugar beets, bacterial wilt of dry beans and soybeans, Rhizopus head rot and Verticillium wilt in sunflowers, Ascochyta blight in chickpeas, downy mildew of camelina, powdery scab of potatoes, and yellow vine in pumpkins.
A number of positive factors have unexpectedly come to light. Over a period of nearly 20 years, the diagnostic lab has provided a needed service for producers and the public, while also generating revenue to help fund technical support. Furthermore, this service has resulted in more than 25 research and extension publications as reports for new or unusual diseases alone.
Lastly, identifying new diseases and their incidence and distribution throughout western Nebraska has provided valuable preliminary data, enabling us to address these real-world disease issues utilizing applied research to develop successful management strategies.