Scale insects on blueberry
Those are not snails but scale insects. The best control is a dormant oil spray that smothers the insects in the early stages. You use a highly refined dormant oil that is formulated to mix with water. You need to keep the spray solution agitated to keep the oil and water from separating. Spray a 2% to 4% solution. Thoroughly spray the plants to cover the insects with oil. We say "spray to drip" meaning the plant is thoroughly covered.