Blueberry leaves are brown
This does not look like a disease or insect issue. This looks more cultural or environmental in nature such as underwatering, overwatering, etc. Make sure the soil drains well.
The soil in the photos looks moist but we do knot know how often you are watering. Blueberry plants require at least one inch of water per week (65 gals./100 sq. ft.). You must supplement rainfall when necessary. The root system is very fibrous but devoid of root hairs. (Root hairs function in most plants by increasing the surface area of the root for water and nutrient uptake.) This characteristic makes the blueberry plant very sensitive to changing soil/water conditions.
Drip irrigation is preferred as it conserves moisture and does not wet the foliage.
Mulch with several inches of mulch and keep away from the base of the stems to conserve moisture. See our website for information on care of blueberries http://extension.umd.edu/growit/fruits/care-blueberries