Powdery mildew peaks in the fall when temperatures are cooler, the sun’s heat and light is more moderate and less direct, and humidity is still high. The amount of dew that forms during the fall is a lot more than in summer months due to the temperature crossing the dew point at a very low place. This happens in the dark, and we all know fungi love dark and wet so, Fall is it for the fungus to go nuts!

Plants with large broad leaves are susceptible. Such as lilac bushes, roses, cabbage, and broccoli.

There are a few organic methods of protecting against powdery mildew. Here are a few:

1. Make a spray with water and baking soda and spray plants early in the day (***on an over-cast day so that this recipe doesn’t burn your foliage***) so that the leaves are dry before the cool night temperatures come. Here’s a good recipe:
   • 1 gallon of water
   • 1 tablespoon of baking soda
   • 1 tablespoon of vegetable oil
   • 1 tablespoon of dishwashing liquid

   This will protect the parts of your plant that have not been infested yet and is preventative only.

2. Neem Oil – apply 70% Neem Oil in mid-summer to prevent, once weekly. If you see some powdery mildew you can start applying it then.
3. Spraying your foliage with tap water from the garden hose at a medium to hard pressure. Summer rains/storms and wind plus direct sunlight keep the powdery mildew from forming in the summer months. So you can re-create some of that in the Fall by spraying plants. Make sure you do this in the morning so the plants are dry by night fall.

You will see a white film coating the top of the leaf. It will be very transparent at first, but as it takes hold it will become more white and apparent. Start treating the plant with one or more methods above immediately in order to save the plant.

Once powdery mildew is present you cannot effectively get rid of it with organic methods. You must remove that part of the plant and GET RID OF IT completely. DO NOT COMPOST! Toss it in the trash! If a large portion of the plant is covered your best bet to contain it, and save other plants from this fungus is to uproot it completely and get it off your property as soon as possible.

This fungus can over-winter in your plant and come back stronger as soon as conditions allow it to start replicating again! Horrible stuff!!!

My 3 year old lilac bush got it last year and I treated it with a baking soda spray. It stopped it from spreading but it had already covered many leaves which were turning yellow and dropping off! I did not know it could survive the winter and come back again or damage the internal plant. The next season the leaves were all strangely shaped and it did not flower. So, I chopped it down to the ground in the hope that some part (the strongest part) would survive and come back as a new baby lilac plant. (I’ll let you know how that goes in the Spring of 2012!)

Good luck with your Fall clean up! It’s time to start your herb seeds indoors if you want nice organic herbs at your finger tips all winter long! You saved some seeds from your cilantro, basil, oregano and thyme plants right?? 🙂