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American brown rot

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Monilinia fructicola
Written by: 
Elizabeth Garofalo

Overview

 

  • Brown rot is caused by two fungi in the northeast: Monolinia fructicola and M. laxa (causal agent of European brown rot): with M. fructicola being the most common of the two pathogens in New England. 
  • The fungus overwinters in mummies and cankers created by the previous season’s infections. 
  • Infections are dependent on the presence of inoculum in the orchard, temperature and wetness.  Optimum development temperatures range from 55°F to 70°F (13°C-21°C) with required wetness times decreasing as temperatures increase.  Below 40°F (4°C), infection is delayed, but not necessarily prevented.
  • Damage from these pathogens manifests as blossom and shoot blight and fruit rot.  Fruit rots both on the tree and post harvest.  When conditions are right, this can result in significant crop loss
  • Cultural management includes removal of mummies and twig cankers during pruning.  Additionally, thinning fruitlets prior to pit hardening (60 days from bloom) can reduce inoculum for later season infection due to rapid decay of infected material.  Chemical control is achieved through targeted fungicidal applications during bloom and fruit ripening.