Plum Curculio and Apple Drop

I don’t spray here but I do bag about 200 apples a year. About 70% of the apples I bag (at nickel size) drop off during the summer. At nickel size most already have PC scars.

Do Plum Curculio cause apple drop? I tried bagging at dime size before PC scars but the stems are weak then and the bags blow off in a modest wind, or drop at June drop.

Anyone else have this problem?

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I don’t know about Curculio. Well, I do, but I blame cosmetic damage on them, not summer drop. I have, in the past, bagged with Maggot Barriers (Footies). Applying the bags is a step in thinning the crop because you have to decide how many bags you have left and how much gumption remains actually to put them all on. Then you whack the remaining fruit off. It’s a way of harnessing your frustration to make sure you don’t get too greedy and leave too great a crop load on the tree. Inevitably, however, the tree has other ideas, and some of the carefully bagged fruit always drops.

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Do you thin the apples before bagging? What cultivars of apple do you have? Some cultivars may over set fruit and experience a larger June drop. And June drop is normal to some extent.

I thin apples, yes, but I don’t bag anymore. Summer drop is worse on some trees and not others, but those that are harder hit differ from year to year. Fireside is consistently the worst, however.

PC in most cases doesn’t cause fruit drop. Well it does on peaches and plums, near-100%, but on apples it is more like 5% or less. I am a bit surprised you are losing nickel-sized apples, if clusters have been thinned to only one apple that one apple usually is hanging on very well. So, I really don’t know what is going on for you. Maybe the bags themselves are for some reason inducing the fruit to drop; keep a few non-bagged controls this year to see.

Another possibility is the trees have not yet reached maturity. Apples tend to hang on to fruits when immature better than some other types of fruit tree, but it is still a factor for apples.


@hambone, serious apple enemies I have are coddling moths, PC and apple maggot flies.

I try to spray Surround as cover spray before I bag as I need fruitlets to size up a bit. I also leave about two apples per cluster and hope those buggers don’t damage them all.

I have fewer June drops when I thin most fruitlets out very early.

I thin religiously at pea size but seems to have no effect on later drops.

My heirloom apples and modern apples all drop the same. Older trees, younger trees, all drop the same.

I will as Scott suggests leave more unbagged controls to compare.

This is why I like figs, pawpaws and persimmons more each year.

Maybe when I put bags on I’m somehow damaging the stem.

I’ve found that cutting a small slit in the middle of a bag helps me avoid damaging a stem when I ziplock a bag tightly.


Yes I make that cut in the middle. I’m grasping at staws for an explanation.

Can you please share what you use to spray (and when) to prevent losing my fruitlets on stone fruit? I have many trees and got zero fruit last summer, everything dropped. I think it was curculio as each drop had a tiny bite in the fruit. Really want to buy the right spray this year!

I had a lot of drops the first couple of year of bagging. Now there are only a few that fall. My opinion is that surround spray allows the fruit to get dime-nickle size with reduced insect damage. I also think that learning to quickly decide which fruit is more dominate in the cluster helps. My trees are older now and I also thin as I bag. The first couple of years I had heavy June drops but not so much anymore. Now I need to work on alternate year fruiting on my apples (goldrush).


My spray routine is in the Guides here:

If you want to use poisons on the bugs, see Alan’s schedule there. I use Surround for the curculio, once you get the hang of it the results are excellent!

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