New York State Flower Industries , Inc
You may have asked this question more than once if you are a grower of Indianapolis White chrysanthemums. The problem of flower damage on Indianapolis cultivars has previously been attributed to two major factors, sun burn or sunscald and botrytis disease caused by Botrytis cinerea. Now there is a third cause of petal burn or necrosis that seems specific to Indianapolis cultivars, especially white. Previous work with peat-lite mixes that had been used to grow successive crops of chrysanthemums had shown a deficiency of B as the suspected cause of a peculiar browning or necrosis of the petals of chrysanthemums. Foliar analysis of leaves taken at full flowering stage of plants showing petal necrosis had B Levels less than the 25 ppm considered critical (1,4). Plant pathology could find no evidence of disease. A particularly unique symptom of the deficiency is the rapidity of its appearance at the time of full bloom. Flowers will be almost ready for harvest when 1 or 2 brown petals may appear. Within 48 hours the condition will affect a third or more of the total petals, making it unsaleable. Curiously enough none of the classical symptoms of B deficiency were seen during the preflowering stages of growth. This has been observed by other investigators working with cotton (3). No symptoms for the first 8 to 9 weeks of growth and then deficiency symptoms in the blooms.
Keywords: Botrytis cinerea Browning Preflowering stages Symptoms Fresh weight