I'm probably wrong, but I don't think that looks like mites...I'm thinking powdery mildew? If it's mites then you should be able to see a real thin webbing in between the leaf fingers right where they grow out of the petiole. You should also basically be able to see them move very slowly across the leaves.
If it's mites then yes get neem oil, mix with warm water, and add 1 teaspoon of mild dish detergent to help the mixture stick to the leaves. Spray everywhere, especially under the leaves.
But check this out first...
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Recognizing Powdery Mildew
It appears in several ways. The most common is a gray-white powdery dusting on the leaf surfaces. The actual color ranges from a white to brownish-white (almost a tan color) and there are few other problems that appear to be similar in the garden. If you see this dusting, it is almost 100% sure you have powdery mildew.
The real tipoff to this problem is when your young leaves start to curl and twist as they develop and do not fully unfurl. Roses twist the entire new shoot. Other plants simply twist the leaves.
Older leaves are pretty much immune to this twisting and usually dont show any other signs other than a dusting or small spots where the outbreak is severe. They will also brown off once the mildew has developed."
There are different sprays for powdery mildew...
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Sulphur sprays are quite effective at stopping the spread of powdery mildew. Remember that they do knock out beneficial soil fungi as well so do only spray to runoff. You can find sulphur in almost any garden shop.
Sodium bicarbonate (baking soda) is recommended by many gardeners and when it is mixed at the rate of between 2 and 10 g per litre of water (add a small dash of liquid soap as a wetting agent). (1 teaspoon to a quart of water) Ive seen research that up to 20g / litre of water has worked well with no burning.
And to just to make your day, it has also been reported (Ive never used this myself) that urine when diluted at 1 part urine to 4 parts water is an effective powdery mildew control. Theres another reason to take a seventh inning stretch.
Milk is another very effective spray for powdery mildew. Mix the milk at a ratio of one part of milk to nine parts of water and spray weekly. Do NOT go higher than 3 milk to 9 water or youll attract other fungus problems that want to feed on the milk. Skim milk works well as it contains no fat to turn rancid (and attract other problems that like the smell of rotting fats.)
There are also products on the garden center shelves featuring jojoba oil and neem oil. I cant speak to these but some gardeners swear by their effectivness for controlling powdery mildew."