( Botrytis cinerea )
A dense grey fungal mass affecting leaves, stems, flowers and fruit of most plants if the conditions are right, also stored fruit and vegetables can be destroyed. Spores are around all the time and are air-borne, requiring wounded tissue for entry and moist conditions to grow. Whole lettuce plants are effected and rot off at the base. Appears as yellow spots on tomato shoots and fruit. Chrysanthemums develop purple spots on their leaves and mummified flower buds. Any attack is at the least disfiguring so prevention is best.
As the infection matures black sclerotia about 2mm accross are produced. These fall to the ground and act as the over-wintering stage.Touching an infected leaf, bud or fruit releases a cloud of spores.
Good hygiene and plant separation to improve air flow, helps prevent attack. In the greenhouse ensure good ventilation and control of humidity to prevent dew formation at night. Removal of any infected material is essential.
Chemical control includes thiophanate-methyl, carbendazim and copper-based fungicides. Armillatox or Jayes fluid can be used on bare soil as a sterilant to kill the sclerotia as part of winter hygiene in the greenhouse.
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