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Necrotic leaf blotch affects only mature leaves and is characterized by the development of irregular necrotic spots that usually appear within a 24-hour period. Most affected leaves turn yellow and drop prematurely within 4 to 7 days. This disorder is restricted to ‘Golden Delicious’ and ‘Golden Delicious’ crosses. Necrotic leaf blotch is associated with 4 to 5 days of cool, wet, cloudy weather followed by sunny hot days.

Necrotic leaf blotch (Babadoost, University of IL)
Necrotic leaf blotch.

(Photo: Mohammad Babadoost, University of Illinois)

Necrotic leaf blotch (Babadoost, University of IL)
Necrotic leaf blotch.

(Photo: Mohammad Babadoost, University of Illinois)

Necrotic leaf blotch (Shane, MSU)
Necrotic leaf blotch.

(Photo: William Shane, Michigan State University)

    

Management:

  • Apply ethylenebisdithiocarbamate fungicides (e.g. mancozeb) beginning a month after petal fall or apply zinc oxide every 14 days from bloom to harvest

    

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