Submitted to: Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2009
Publication Date: 7/29/2009
Citation: Olanya, O.M., Honeycutt, C.W., Larkin, R.P., Griffin, T.S., He, Z., Halloran, J.M. 2009. The effect of cropping systems and irrigation management on development of potato early blight. Journal of Plant Pathology. 75:367-375. Interpretive Summary: Early blight is an increasingly important disease on potato. Crop, soil and irrigation management have the potential to modify crop microclimate, and concurrently to enhance early blight disease control. During a two year period, we assessed different crop management systems for their effects on early blight disease potential. Early blight incidence was considerably lower in several management systems compared to continuous potato production. Similarly, pathogen lesions and disease severity were lower in these systems compared to continuous potato. This suggests that management systems that do not grow potatoes immediately after potatoes, year after year, may enhance control of early blight disease.
Technical Abstract: Crop and soil management may modify canopy and belowground microclimate. However, their effects on potential development and control of early blight are not well documented. Crop management systems [Status Quo (SQ), Soil Conserving (SC), Soil Improving (SI), Disease Suppressive (DS), and Continuous Potato (PP)] were evaluated for their effects on early blight potential under irrigated and rainfed conditions. In 2006 and 2007, microclimatic data were recorded with a data logger deployed at the canopy level. Early blight was determined by visual assessment of symptoms and predictions from the Tom-Cast model. Early blight incidence and lesion numbers varied among cropping systems and between years. Disease incidence ranged from 31-64% (2006) and 12-43% (2007), and was significantly higher in PP compared to DS, SQ, SC, and SI systems. The relationships of Alternaria solani incidence and disease severity with microclimate varied and were mostly non-significant, suggesting that development of A. solani was not affected by microclimate. Early blight incidence was significantly associated with cropping systems. Prediction of early blight based on the Tom-Cast model was not correlated with observed disease levels. This research demonstrated that early blight disease is enhanced through continuous potato production.