Epiphytic Pseudomonas syringae on Dry Beans Treated with Copper-Based Bactericides

Area of Science:

• Plant Pathology
• Bacteriology
• Agricultural Science

Background:

• Epiphytic bacteria, including Pseudomonas syringae, can colonize dry bean plants.
• Copper-based bactericides are used to manage bacterial diseases in crops.
• Understanding the efficacy and impact of bactericides on epiphytic populations is crucial for integrated pest management.

Purpose of the Study:

• To evaluate the response of epiphytic bacteria, particularly Pseudomonas syringae, on dry bean plants to copper-based bactericides.
• To compare the copper resistance of different pathovars of Pseudomonas syringae.
• To assess the implications of bactericide application on epiphytic bacterial populations for pest management.

Main Methods:

• Field evaluation of four copper-based bactericides on pinto bean plants.
• Quantification of epiphytic bacterial populations on leaflets, flowers, and pods.
• Measurement of copper resistance in recovered Pseudomonas syringae strains using cupric hydroxide-amended media.

Main Results:

• Copper bactericides showed minimal differences in efficacy but occasionally reduced epiphytic populations on bean organs, especially after repeated applications.
• A trend toward a relationship between epiphytic populations on leaflets and flowers was observed, but with instances of population disparity between organs.
• Pseudomonas syringae pv. syringae strains exhibited significantly greater copper resistance compared to Pseudomonas syringae pv. phaseolicola strains.

Conclusions:

• Copper bactericides have limited efficacy in controlling epiphytic Pseudomonas syringae populations on dry beans.
• Differential copper resistance between Pseudomonas syringae pathovars is a key factor influencing population dynamics.
• These findings suggest that integrated pest management strategies should consider the varying copper resistance of bacterial pathovars.