Fruit drop can happen for

Fruit drop can happen for many reasons: 1) Do you see any sign of insects? Plum curculio is a snout beetle that causes problems and you need to use a fruit tree spray at petal drop and up to 6 weeks after. 2) How is your soil? Plum trees do not do well in wet or compact soil; well-drained sandy loam is best. 3) Do you have plenty of sunshine? 4) Do you have pollinators? Unpollinated flowers will bear fruit, but they abort. 4) Are you thinning your fruit? 5) Are you watering enough? The amount of water needed depends on the size and age of the tree and weather conditions, but a first-year tree uses 5 to 10 gallons of water per week in the summer. The soil on the surface may be dry, but the soil at the root zone needs to be moist 4 to 6 inches down. Occasionally, you can dig down and see if it's moist (but not water logged).