Answer: I wonder if they are being attacked by tarnished plant bugs (TPB)? These small bronze-colored insects are very quick, and fly off or hide when you approach the plant. They suck the juices from blossom parts, buds, and succulent new growth, and often cause blossom distortion and bud drop. Look at the blossom stems. If there are sunken brownish marks, the problem is most likely TPB. You can protect your plants by covering them with a fabric row cover (available at many garden centers and via mail order). Be sure to first sweep through the patch to cause the TPBs to fly away, so they aren't captured and protected under the fabric. You can also spray the plants with pyrethrin before covering them.
Another problem may be extreme heat or wide swings in temperature. Pollen can die at extreme temperatures (above 90 during the day, above 75 at night), so blossoms fall without fruit forming. There's not much you can do about the heat, other than trying to shade the plants, but you can keep them healthy with proper moisture and feeding so they'll be ready to produce when the weather cools down. Best of luck!
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