Effect of canopy manipulation on cane and fruit Botrytis in protected raspberry

Area of Science:

• Plant Pathology
• Horticultural Science
• Agricultural Entomology

Background:

• Botrytis cinerea is a major pathogen affecting raspberry fruit and canes.
• High incidence of fruit botrytis was observed in commercial crops, including protected and fungicide-sprayed fields.
• Latent infections in unripe fruit did not predict post-harvest rot.

Purpose of the Study:

• To assess the incidence of Botrytis cinerea in commercial raspberry crops.
• To investigate the efficacy of canopy manipulation (leaf removal and cane thinning) in reducing fruit and cane infections.
• To understand the relationship between canopy density, humidity, and disease development.

Main Methods:

• Surveyed 19 commercial raspberry crops for Botrytis cinerea incidence.
• Conducted field experiments involving leaf removal and primocane thinning in two commercial crops.
• Monitored fruit and cane infection rates and internal canopy humidity.

Main Results:

• No significant differences in fruit infection incidence were found between open-field and protected crops, or between sprayed and unsprayed crops.
• Canopy thinning reduced internal canopy humidity in a high-density crop (20 canes/m) but not in a lower-density crop (10 canes/m).
• Canopy thinning significantly reduced leaf and cane infection in the dense crop but did not significantly reduce fruit botrytis.

Conclusions:

• Canopy manipulation can effectively reduce cane infection in dense raspberry crops under high disease pressure.
• Direct infection of canes by Botrytis cinerea is likely in dense, protected canopies.
• Fungicide applications and crop protection methods did not fully control fruit botrytis in the surveyed crops.