Impact of zebra chip disease and irrigation levels on potato production

While many studies on zebra chip (ZC) disease in potatoes have focused on the epidemiology of the disease and the characterization of infected potato plants, this study quantifies the impact of ZC disease on crop response and investigates the relationship between irrigation level and ZC disease severity. In this two-year study chipping potatoes were planted under a variable rate irrigation center pivot sprinkler using a split-plot design with a 2 × 3 factorial combination of ZC disease level (diseased and non-diseased) and irrigation levels of 100%, 80% and 60% replenishment of soil water depletion to field capacity, designated I100, I80 and I60. Crop response of tuber yield, evapotranspiration (ETc), crop water productivity (CWP) and irrigation water productivity (IWP) from ZC diseased plots were compared with non-diseased (control) plots. Tuber yield and CWP in the infested plots were significantly reduced by at least 58% in 2018 and by 21% in 2019 as compared with results in the control plots. Year significantly affected crop response in the control plots, however, crop response in the ZC diseased plots was devastative to potatoes from year to year. There was no interaction between irrigation level and ZC disease occurrence. In both years, stomatal conductance measurements in ZC diseased plants were reduced 35 and 44 days after infection as compared with control plants. Since irrigation did not lessen the severity of ZC disease, as soon as diseased plants are identified within a field, withholding irrigation to the affected areas could improve IWP at the field level. Future studies should consider the use of thermal imaging or spectral reflectance of the plant canopy for spatiotemporal detection of ZC disease as early as possible in the growing season.