Sunday, February 13, 2011
As all Melbournians will attest, this summer has been one wet weekends and humid nights. No doubt has the wet been good for our gardens and catchments, but the humidity has been rather unpleasant and it has been these humid conditions that our Crepe Myrtle - Lagerstroemia – has succumbed to Powdery mildew.
Powdery mildew or Uncinula necator is disease mostly common in viticulture when the conditions in the canopy are humid and dense. It is a disease that may overwinter inside dormant buds which enables the fungus to infect shoot growth in spring, and in very humid conditions look like these pictures. Because this part of the tree does not get a lot of direct sunlight, virtually none actually, and constant humidity and temps of around 25°C-29°C have been common this summer, Powdery mildew has gone nuts in this case.
Right now there is not a lot to do, so it is next year you have to think about. Once leaf fall happens use a wettable sulphur spray, and if you are worried about it not being good for the environment don’t worry; this is an organic substance and you can get uber friendly sprays from your local garden centre. If it is a real problem throughout your tree/shrub/grapevine what you will need is a systemic fungicide.
So, if you are coming around to mine for a BBQ, don't go sniffing around the back of my Crepe Myrtle for a look-see cos' any spores that are still present could stray onto your trendy boat shoes and settle on your award winning Fycus!