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Manganese bark necrosis or measles is manifested as an uneven bark surface with purplish raised pimples and dark deposits below. It is caused by an excessive uptake of manganese from the soil. A low soil pH of 5 or below makes manganese much more available and leads to this disorder. Symptoms show up primarily in ‘Red Delicious.’

Manganese bark necrosis (Strang, UKY)
Manganese bark necrosis.

(Photo: John Strang, University of Kentucky)

      

Management:

  • Apply lime prior to establishing orchards to attain a soil pH of 6.5
  • Maintain soil pH as a preventative measure

   

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