Explain it to me...plum curculio in apples



I think it really depends on when those pests emerge from the ground. Last year, I saw bite marks on my tiny apples.

I am worried about this year because it’s already relatively warm. This fact sheet from Cornell is a good summery.


Look at picture #4. They get to the fruit real fast.


That was my problem last year, even spraying at petal fall I had loads of affected fruitlets.


I think suggestion of spraying at petal fall is to avoid killing bees and other pollinators working on fruit flowers. Techincally you can spray before that. That said, you may want to consider Surround if you choose to spray before petal fall.

Or not waiting until all petal fall. If you should to spray chemical and you have high pest pressure, you may choose to spray at 70-80% of petal fall instead.


Yeah, those are pea size and got bitten in photo#4. So far I am lucky at peanut size and no bite.



Here are two photos that, I believe, show PC damage. In the four-apple photo there is unknown insect damage and ?? injury as well. Do the injuries surrounded by ‘scab’ mean feeding hole, or eggs deposited but no crescent? On the low-res photo my one lone Braeburn (new-ish tree, thinned) has marks that also look like feeding, I guess. (Edit: Looking further on the interwebs I see that the bites[?] on the Braeburn could be some other creature.) I am going to try bagging ASAP, and removing anything that looks like there may be eggs laid. I just have one orchard apple and about maximum 20 fruit on the old tree in the woods that I’m trying to save. I’d be happy to only have 10 of those apples if I could maybe break (or hamper) a cycle at the beginning of the orchard’s life. All info appreciated…this is leaf two for some trees and leaf one for the rest.


A guessing game from me.

In the first pic, the two upper apples looked like the damage done by tarnished plant bug. The lower right probably caused by a caterpillar eating the surface and left a scar. The lower on the left, I am not sure.

The second picture reminds me of a bitter pit issue

Hopefully those who know wil chime in.


Basic Question: Is Plum Curculio damage to apples merely cosmetic, surface damage that does not extend into the apple?


It is pretty bad here if I don’t bag the fruits. The fruits will deform badly and premature drop.



The problem is if the fruits either drop or stop developing after being stung, the curcs will grow and then become adults and game starts over. If the apples grow, they will be deformed but the curc eggs get squished.


Does that include apples? I see lots of bites on apple fruitlets, but I’ve never seen early drop. Some years I see some deformities on apples, but I assume that is from something like stink bugs or tarnish bugs. Last year there was an unsprayed seedling apple tree that had over half the fruit bitten, yet no early drops and no deformities.


Here are some photos.



Is that PC damage?




The one on the right is apple maggot, and I think the one on the left is codling moth


Wow, those are some ugly apples! Luckily I don’t see too much damage like that on my unsprayed trees. It is usually only one type of pest on certain years that target very specific varieties. It would be nice to know, in advance, what the pest of the year will be. What type of bag do you use on your apples?

Yeah, but a grub ID is the only way to know for sure.


I used the sandwich zip lock bags. I make a small angle cut on the two bottom corner and zipped the king apple aka the largest apple in the cluster and pruned the others off.



Tony- when do you bag your apples? Last year I did it at dime size and almost all blew off, stems weren’t strong enough yet. Is nickel or quarter the right time?


I do it at dime size. I think that when they drop it’s cause they were going to drop anyway. Waiting much longer exposes them to more pest damage


@ltilton OK thanks. It seemed the bags acted like a sail and catch the wind and rip the apples off the tree. I guess it could have been the squirrels. When do the codling moth and apple maggot hit? All my apples already have PC wounds.


Petals dropped over the weekend , Sunday night I did a surround spray with neem. Tonight, Monday, I found some new pc damage even on sprayed pea size apples. I guess pc is active on these warm nights, we have hit new highs temps here in the Midwest. I usually wait till at least dime size to bag, but I do bag apples that pc got to first!