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    Farming & Crop Protection Downy mildew (bulb vegetables)

    Downy mildew (bulb vegetables) [Peronospora destructor]

    Bulb yield and storage life are reduced by the plants becoming infected and the foliage dying.

    overview

    Downy mildew (bulb vegetables) - image 1

    Downy mildew (bulb vegetables) - image 1

    Downy mildew (bulb vegetables) - image 2

    Downy mildew (bulb vegetables) - image 3

    Downy mildew (bulb vegetables) - image 4

    Pest Profile

    • Symptoms & Diagnosis

      Occurence

      Overwintering bulbs and crop residue are primary infection sources. Cool nights with dew condensation and moderately warm days favor the spread of the fungus.

      Pattern of damage

      Elongate-oval, light-gray infection sites which may be covered with a purple-gray layer of spores (Pictures 1 & 2). The foliage may die back completely (Pictures 3 & 4). Brown spots on infected bulb soil.

      Treatment

      Combat

      Adequate crop rotation program, at least 3 years between susceptible crops and removal of crop residue. A fungicide treatment program should start at the beginning of infection.