|Workneh, Fekede -|
|Henne, Donald -|
|Whipple, Sean -|
|Bradshaw, Jeffery -|
|Rashed, Aresh -|
|Paetzold, Li -|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 8, 2013
Publication Date: November 20, 2013
Citation: Workneh, F., Henne, D., Goolsby, J., Crosslin, J., Whipple, S., Bradshaw, J., Rashed, A., Paetzold, L. 2013. Characterization of management and environmental factors associated with regional variations in potato zebra chip occurrence. Phytopathology. 103:1235-1242. Interpretive Summary: Knowledge of factors which contribute to development and spread of plant diseases is essential in development of management practices. In this study, several environmental and management factors were assessed for their effect on potato ZC occurrence from south Texas to Nebraska. The findings that field locations, planting dates, and temperature are significant factors in ZC occurrence suggest that one may need to take these factors into account when considering management options.
Technical Abstract: Potato zebra chip (ZC) disease, putatively caused by the bacterial pathogen ‘Candidatus Liberibacter solanacearum’, which is vectored by the potato psyllid (Bactericera cockerelli), has caused widespread damage to the US potato production ever since its first discovery in south Texas in 2000. In the central US, potatoes are cultivated from south Texas to the Canadian border under diverse environmental conditions. To understand the influence of environmental conditions and management practices on ZC occurrence across the region, data on meteorological variables, planting dates, insecticide applications, field locations (GPS), and psyllid population numbers were collected over a three-year period (2010-2012) at six locations. From these locations, ZC-symptomatic plants were counted in 26 fields and related to the variables using multivariate analyses. The variables correctly classified 88.5% of the fields into relatively low or high ZC intensity levels. Of all the variables, location, planting date, and maximum temperature were found to be the most important variables in distinguishing between ZC intensity levels. Surprisingly, counts of total psyllid populations and the number of insecticide application did not contribute to variations in ZC occurrence. Counts of total psyllid populations also did not correlate with any of the variables. However, there was a low but significant (r = -0.44983, P = 0.0211) negative correlation between counts of psyllids testing positive to Liberibacter and latitudinal locations, indicating a south-to-north declining trend in incidence of Liberibacter in psyllid populations. A similar declining trend also was observed in ZC occurrence (r = - 0.499, P = 0.0094).