If it's planted facing east, and there's a frost, it will damage the buds and they tend to turn brown and sickly and drop off. Do you have cold winters where you live?

A few other things will cause this:
Drought when the buds are trying to open.
Excessive rain or sprinkling when the buds show color, which encourages a harmful fungus.
Heavy feeding too close to bud break.
Or salt in the soil or water. Uncommon in Louisiana, but possible near the Gulf.