The Effect of Bacterial Isolate of Pseudomonas fluorescens pf1 on the Growth of Tomato Plants and on Reducing its Infection with Bacterial Speck Disease Caused by Pseudomonas syringae pv. tomato

Abstract

Bacterial speck disease is one of the most important bacterial diseases that affect tomato plants, which spreads in all countries that grow tomatoes in greenhouses and open fields, and causes heavy losses in quantity and quality. Due to the difficulty in combating speck disease chemically, the research was aimed to evaluate the effect of the bacterial isolate Pseudomonas fluorescens pf1 on the growth of tomato plants and on reducing the infection with bacterial speck disease caused by the bacteria Pseudomonas syringae pv. tomato. This research was carried out during the 2020/2021 season. Tomato seeds were inoculated with the suspension of beneficial bacteria P. fluorescens (10⁹ cells/ml) by soaking before planting. Three weeks after transfer to plastic pots, the artificial infection was carried out by spraying each plant with P. syringae pv. tomato suspension. Readings were made two weeks after infection by estimating the disease incidence and severity and estimating some growth indicators of tomato plants (foliage fresh and dry weight). The results obtained showed a positive effect of the bacterial isolate, P. fluorescens, on the growth of tomato plants, by significantly increasing the fresh and dry weight of foliage compared to the untreated control plants. Plants treated with beneficial bacteria also showed a decrease in the disease incidence and severity, reaching 56 and 40% in plants treated with beneficial bacteria, respectively, compared to control plants infected with pathogenic bacteria and not inoculated with beneficial bacteria (89% and 60%, respectively). In conclusion, this study showed that treatment with the beneficial bacteria P. fluorescens can be considered as one of the promising components to control bacterial speck disease and reduce the damage it causes on tomato crop.

Keywords:

Bacterial speck disease, tomato, Pseudomonas fluorescens, Pseudomonas syringae pv. tomato, disease incidence and severity.