Botrytis cinerea - 'The Grey Mould' attacking Geranium Flowers
We had a few wet, cloudy, days in succession that did serious damage to the floral parts of the geranium plants in my garden. Leaves and stems of geranium are not affected by this fungus. see below for another image
Geraniums are great bedding plants in Ontario. I put a cluster of mixed red and white at each side of my front garden and they flower all summer long. Start them off from small four inch pots that cost a couple of dollars. You KNOW they are going to grow well and they are FLOWERING the day you put them in continue to flower until a heavy frost comes along. This year they are still fowering nicely in the middle of October. Every week or so you must dead-head the spent flowers but there are always other blooms coming along to take their place. They do well enough in the hot dry weather of summer, providing you give them 10 seconds with the hose every few days, and a shot of 20:20:20 once a month gives them a nutritional kicker. Make sure when you water that you don' t get the blooms wet for prolonged periods for this is their nemesis. The flowers are very susceptible to Grey Mould caused by Botrytis cinerea. Botrytis attacks old blossoms on many flowers. Most of the time you don't even notice it is there but, believe me, it is lurking around waiting for its opportunity. In the case of Geraniums, Botrytis doesn't wait until the blossoms are senescent but attacks at any stage to make the flower heads very messy and visually unappealing. More than this, the 'Grey' material is a powdery mass of spores that looks like grey dust covering the blossoms. When disturbed these microscopic spores fly off in all directions to other attractives sites. One of my favourite pictures was taken in a strawberry patch and shows Botrytis making short work of some ripe strawberries (click here) although the reproduction here is a poor reprentation of the original.
Images from MycoAlbum CD copyright George Barron