Botrytis Leaf and Flower Spot of Gladioli

Botrytis gladiolorum

Description:

A fungal disease causing a small, circular, red brown spot on leaves initially that may grow into a more irregular shape with a grey centre, brown edges and a dark brown rim. Grey, furry, hyphae may develop under humid conditions and cover and kill the leaf. It may progress into the stem and cause neck rot after which the plant goes yellow and falls over. Black sclerotia (the fruiting bodies that carry the fungus to the next season) may form in the dense grey, hyphal growth that also produces masses of spores at the base of the plant.
Infected flowers usually have water soaked spots near the edges of the petals that become white or brown or white with a brown rim. The petals become slimy and produce masses of spores in humid conditions.

Species Affected:

Gladioli

Biology:

Favoured by rainy and damp weather.
Corms are usually infected at digging where spores from the tops contaminate them. The spores then germinate and enter the corm forming white bands and the rotted areas dry out and shrivel. Sometimes the rot travels down the centre of the corm leaving the outside intact.

Life Cycle:

Origin and History:

Distribution:

Significance:

Management and Control:

Destroy infected plants and remove and destroy spent flowers.
Dig corms in dry weather as early as possible and cure at 350C for a week.
Store corms in dry well ventilated areas.
Rotate Gladioli to new ground each year.
Apply fungicides and use a wetting agent to assist penetration into the corm area.

Related and Similar Species:

References:

1291

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.