First Time Grow Black Indica

You can definately do some defoliating opening up the inside of the plant to provide better air circulation and more light to the center.You should do it in stages to limit the amount of stress on her. If possible only water the soil without wetting the foliage. Since she is still in veg if all else fails you can use a product containing Neem oil to treat the mildew. Once flowering begins you should stop using the neem. Also do not spray her in direct sunlight. Start with half the recomendations dosage to see how she reacts.There are also some other homemade remedies on the internet using milk supposedly the lactic acid in the milk inhibits mold.

Forgot to mention you can also try to use a nutrient product containing silica which helps your plant build stronger cell walls you can use it as a foilage spray which would be most effective or add it to your nutrient routine via soil watering

I am also growing in Southern Ontario my friend and I am also having the same issues along with a minor spider mite problem(I hope). I can't do enough to keep that powder off the leaves. Stay true to the organic greens :)