Fungicide Application for Late Blight Management: A Boom Attached to a Center Pivot Irrigation System

Area of Science:

• Agricultural Science
• Plant Pathology
• Pesticide Application Technology

Background:

• Late blight, caused by Phytophthora infestans, is a major potato disease.
• Effective fungicide application is crucial for managing late blight in commercial potato production.

Purpose of the Study:

• To compare the efficacy of two chlorothalonil application methods for late blight control in potato.
• To evaluate the impact of application method on fungicide residue levels and disease severity.

Main Methods:

• Chlorothalonil was applied via center-pivot irrigation versus an attached spray boom in potato fields (cvs. Russet Norkotah and Russet Burbank).
• Fungicide efficacy was assessed by inoculating excised leaves with Phytophthora infestans strains (US-1 and US-8) and measuring disease severity.
• Chemical residue analysis was performed to quantify chlorothalonil levels on leaves.

Main Results:

• Disease severity was significantly lower 6 days after application when chlorothalonil was applied using the attached boom system.
• Fungicide residues were approximately three times higher with the attached boom compared to the center-pivot system.
• Strain US-8 of Phytophthora infestans caused more severe disease than strain US-1, and disease severity was inversely related to chlorothalonil residue.

Conclusions:

• The spray boom attached to the center-pivot irrigation system is a more effective method for applying chlorothalonil to manage potato late blight.
• Higher fungicide residues achieved with the boom system contribute to improved disease control.
• Understanding pathogen strain virulence and optimizing fungicide application are key for effective disease management.