That doesn't look like anything serious. Blueberries will take full sun in pretty hot conditions if they are in good soil and well watered. But shade cloth of about 50% shade will make it easier in hot weather.

Keith, here in S. Calif, blueberries do appreciate some afternoon shade. But to me, it looks more like this is a pH issue. Are you growing your blueberries in the ground or in pots? When the leaves start to turn reddish, it can mean the pH is getting a bit too high. Also, too much salt in the water or accumulated salts in your soil can turn the tips of the leaves brown. Same with too much fertilizer (salts in the fertilizer). That can be resolved by flushing the blueberries well with water. This is an off chance, but some folks have water softeners hooked up to the entire watering system. Doubt this is the case, but always something to consider. I would suspect being in Playa Del Rey, you have a fair amount of salt in your soil, like I do. So, a good flushing with water will help remove accumulated soil salts if these are planted in the ground. Add some soil sulfur (be careful, a little will eventually go a long way), and also water with some diluted aluminum sulfate if this is a pH issue.

Patty S.