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United States Department of Agriculture

Agricultural Research Service

Research Project: BIORATIONAL CONTROL METHODS FOR INSECT PESTS OF POTATO

Location: Fruit and Vegetable Insect Research

Title: Susceptibility of Potato Cultivars to Purple Top Disease

Author
item MUNYANEZA, JOSEPH

Submitted to: Potato Country USA
Publication Type: Popular Publication
Publication Acceptance Date: March 26, 2009
Publication Date: N/A

Interpretive Summary: Since 2002, Columbia Basin potato growers in Washington and Oregon have experienced serious outbreaks of potato purple top disease that causes significant yield losses and a reduction in tuber quality. It has been determined that the beet leafhopper-transmitted virescence agent (BLTVA) phytoplasma is the causal agent of the disease and this pathogen is transmitted by the beet leafhopper. Researchers at USDA-ARS Wapato and Prosser, WA conducted studies to determine susceptibility of important potato cultivars grown in the Columbia Basin to purple top disease. It was found that most, if not all, of the cultivars grown in the Columbia Basin are susceptible to purple top disease. Information from this research will help growers effectively manage purple top disease in potatoes by providing information on varietal susceptibility and the need to protect vulnerable cultivars.

Technical Abstract: Since 2002, Columbia Basin potato growers in Washington and Oregon have experienced serious outbreaks of potato purple top disease that causes significant yield losses and a reduction in tuber quality. It has been determined that the beet leafhopper-transmitted virescence agent (BLTVA) phytoplasma is the causal agent of the disease and this pathogen is transmitted by the beet leafhopper. A three year-field trial funded by Washington State Potato Commission was conducted by a research team led by Joe Munyaneza, research entomologist at USDA-ARS in Wapato, WA and Jim Crosslin, plant pathologist at USDA-ARS in Prosser, WA, to determine susceptibility of important potato cultivars grown in the Columbia Basin to purple top disease. Potatoes were planted in May 2006, 2007, and 2008 in small field plots at the USDA-ARS Research Farm at Moxee, WA. Potato cultivars planted include Ranger Russet, Russet Burbank, Umatilla Russet, Norkotah Russet, Shepody, and Alturas, as well as chipping varieties FL-1867 and FL-1879. Potatoes were sampled weekly for leafhoppers and monitored for purple top symptoms. Over the three years of the study, purple top disease incidence in potato plants averaged 33.6, 23.3, 19.4, 12.8, 8.0, and 2.3% for Norkotah, Ranger, Umatilla, Alturas, Shepody, and Russet Burbank, respectively. In addition, disease incidence averaged 9.3 and 4.4% for chipping cultivars FL-1879 and FL-1867, respectively. Results of the study clearly showed that most, if not all, of the cultivars grown in the Columbia Basin are susceptible to purple top disease. Russet Burbank appears to be resistant to or tolerant of the disease, as this cultivar had the lowest disease incidence and plant symptoms were not observed until toward the end of the growing season. Low incidence was also observed for the chipping variety FL-1867. Information from this study will help growers effectively manage purple top disease in potatoes by providing information on varietal susceptibility and the need to protect vulnerable cultivars.

Last Modified: 8/27/2014
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