Submitted to: Crop Protection Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/2/2006
Publication Date: 8/25/2007
Citation: Olanya, O.M., Starr, G.C., Honeycutt, C.W., Griffin, T.S., Lambert, D.H. 2007. Microclimate and potential for late blight development in irrigated potato. Crop Protection Journal. 26:1412-1421 Interpretive Summary: Application of irrigation water can improve potato growth and tuber yield in years of deficit rainfall. However, its effect on potential for potato late blight development is not fully understood. The effects of sprinkler, sub-surface drip, and surface drip irrigation treatments on late blight susceptibility were assessed on Russet Burbank potato in 2003, 2004 and 2005. The potential for late blight was assessed using a simulation model. The amount of water application differed among years and treatments. The day to night cycle of variability measured in the field indicated that irrigation had only a slight effect on late blight development in this humid region. The dominant effect on late blight development appears to be the regional climate. Much less irrigation water is required in the wet and humid region of Maine, so even un-irrigated production can have a high susceptibility for late-blight development. The model accurately predicted blight progression in potato. In 2004, significant differences in simulated disease levels were noted between all treatments and the un-irrigated plots. The micro-climate within the potato canopy was less impacted by irrigation treatments than by regional weather; however, the potential for late blight development increased slightly in the surface-drip and sprinkler irrigations. Within the climatic constraints of this study, it appears that potential for late blight is not a significant factor influencing choice of irrigation systems.
Technical Abstract: Application of irrigation water can improve potato growth and tuber yield during periods of deficit rainfall. A variety of water application techniques exists; however, little is known of their relative impacts on potato late blight potential. The effects of sprinkler, sub-surface drip, and surface drip irrigation treatments on microclimate and potential for late blight development were evaluated on Russet Burbank potato over three growing seasons in central Maine. Leaf wetness, air temperature, relative humidity (RH), rainfall and soil temperature were recorded each year. The potential for late blight was assessed with a late blight simulation model. Leaf wetness and RH peaked during night hours, while canopy and soil temperatures were lowest during the same hours. Comparison of observed and simulated blight development revealed a good prediction of potato late blight by the simulation model. The onset of simulated blight severity and final predicted disease level differed among years. Slight differences in simulated disease levels were sometimes observed between irrigated and the non-irrigated treatments; however, irrigation application method did not consistently impact microclimatic parameters associated with late blight development. These results indicate that microclimate conducive to late blight development was less impacted by irrigation treatments than by local macroclimatic conditions.