A white powdery film on my Dogwood leaves. What would cause that?

Powdery mildew..... fungus. Use copper sulfate spray to kill it, Bonide makes a good garden spray..... https://www.amazon.com/Bonide-Copper-Fungicide-Rtu-Natural/dp/B000UJVDXY/ref=asc_df_B000UJVDXY/?tag=hyprod-20&linkCode=df0&hvadid=198106292047&hvpos=1o3&hvnetw=g&hvrand=1974247627800410094&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9033057&hvtargid=pla-350570734756&psc=1 found in most garden departments

Hi Dj, It's mildew. Here's a link that may help: http://homeguides.sfgate.com/rid-powdery-mildew-dogwood-31560.html

Good luck!

Often happens in moist areas , no surprise in WA , I guess ! Provide "air drainage" by pruning to discourage foliage that's too close . When pruning destroy branches , or fungus could remain active in compost or if you toss them in the woods .

Powdery mildew, provide better air circulation, don't water in the pm, remove any leaves on the ground/don't compost them, and cut back on the irrigation. Should clear it up. You can use the copper sulfate spray, but if you don't make changes you will just be dealing with it again.

I had bought some natural spray it was Dr something and was in a red liquid sprayer used for many things including using it on dogs

for fleas and ticks. Safe for vegetable believe it has red pepper on it

Does anyone know the correct name? Works very well especially for the tomato worms.

Your trees have mold. Too much moisture creates this problem from watering too much overhead or and heavy humidity Please don't use copper spray, it is a heavy metal and if you get any overspray on you, it will go into your skin and stay in your body. Use baking soda, water and a little bit of liquid hand dishwashing liquid. In a gallon of water, add 1 teaspoon of baking soda, 5 drops of liquid soap, shake up and spray. Do this in the early morning and never when the sun is out as it will burn the leaves. And, yes, pruning to get air thru the limbs is always a good idea. The best description of this, prune so a bird can fly thru the limbs.