Plums - AU Rosa and AU Amber fruit drop

I’m in zone 7a (central Kentucky).

I’ve had AU Rosa and AU Amber in the ground for 6 years. The trees grow very well. The Amber in particular is a very healthy and strong tree (Rosa gets eaten by Japanese beetles, but still increases in size each year)

They both blossom like crazy. A few years ago they started setting fruit, but it drops off. It used to drop off when small, now they seem to let fruit get to almost ping pong ball size before they all drop off. I have yet to have even 1 fruit reach maturity.

Is this a normal part of the trees maturing and they will eventually hold fruit, or is something wrong? (a nutrient missing, etc?)

Our Stanley Prune plum tree also dropped about 1/2 it’s plums last week. The remaining plums look good.

If you don’t spray your trees I’d guess PC. The years I don’t spray all of them end up bitten and either drop or rot. It’s normal for some to drop though.


Every plum that got hit by Plum Curculio is currently dropping right now for me and they are just about ping pong ball sized. I would suspect PC. I’d inspect some of the fallen plums and look for the telltale crescent cuts

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Can I ask what you spray them with?

consult the numerous threads on Plum Curculio

Plum Curculio - General Fruit Growing - Growing Fruit
Plum curculio 2024 - General Fruit Growing - Growing Fruit
Plum Curculio (PC) Questions and tips - General Fruit Growing - Growing Fruit
Low Spray Synthetic Short Version - Guides - Growing Fruit

Imidan is my favorite. It must be respected.

I was happy to give it up. If you aren’t making 100 gallons of mix dealing with that powder is a PIA. Also, it is weak against plant bugs and pear psyla.

The materials I use now are cheaper, easier to handle, much less toxic to mammals and take out a wider range of my pests.

I agree the power is a PIA. It’s important to wear your mask when handling the powder as well as the spray. My biggest issue is PC and codling moth. It’s economical and works great for me on those pests.
I do find it’s terrible smell helps me practice caution.

Alan, what do you use for PC and codling moth?