Effect of different irrigation rates on the occurrence and development of potato bacterial lenticels rot in Egypt

"Lenticel rot" is a type of soft rot that develops within potatoes' natural openings due to increased respiration rates. When potatoes are exposed to waterlogged soil and high temperatures, their lenticels expand, providing an access route for pectolytic bacteria. This study is the first to shed light on lenticel rot in Egypt. The study's goal is to investigate how inappropriate watering rates affect the development of lenticel infections. The causal bacteria were identified as Pectobacterium carotovorum subsp. carotovorum using both BIOLOG analysis and DNA sequencing, following the pathogenicity test. In a pot experiment (with 4 kg of soil in each pot), the highest watering rate (1000 mL per pot), combined with soil infestation, resulted in the greatest disease incidence. The ratio of infected (IR) tubers increased from 0.0±0.0 in the treatment without infestation to 65.4±10.7 in the infested treatment (P < 0.001) under the high watering rate. No significant difference in IRs was observed between the different watering rates in non-infested treatments. Additionally, there was no significant difference in IRs between non-infested and infested treatments following regular and moderate watering rates (500 mL and 750 mL, respectively). High irrigation rates altered soil chemistry, decreasing organic matter (OM) and nitrogen (N) availability while increasing phosphorus (P) and potassium (K). In conclusion, the irrigation rate has a significant impact on disease development compared to the sole presence of the pathogen in the soil. This implies that the irrigation rate influences disease development only when the pathogen is actively present.