Effect of photoperiod and temperature on common blight disease of common beans (Phaseolus vulgaris L.)

Summary Although common blight disease is serious in many dry bean production areas, there is only limited information on the influence of photoperiod on the disease. Experiments were conducted in growth chambers and in the field (Nebraska, Dominican Republic, Puerto Rico) to investigate the influence of photoperiod × temperature and photoperiod, respectively, on the reaction of cultivars/lines to the causal bacterium Xanthomonas campestris pv. phaseoli. A split-plot design was used in all experiments except in the DR experiment where cultivars/lines were replicated within each photoperiod treatment. The disease reactions were more severe on cultivars/lines under short photoperiod and under higher temperature than under longer photoperiod and lower temperature in the growth chamber. Disease reactions were also more severe under the short photoperiod in the field experiments. No interactions were detected among these factors. These results have important implications for plant breeders in the evaluation of common blight disease reactions in different latitudes.