Explain it to me...plum curculio in apples


This should be pretty basic thing to know, but I still don’t really grasp PC damage in apples.

To start: I’m growing fruit for me, doesn’t have to be perfect. Also, I prefer not to spray. Last year I did a spectracide spray after petal drop and still had PC damage on the large majority of apples. They didn’t really bother the pears. There are multiple large, old apple and pear trees in the neighborhood that are pretty much ignored and left to the deer/squirrels which I’m sure harbor lots of fun pests.

If I do not spray for Plum Curculio and later on bag my apples, what will happen to apples (and pears) that have eggs laid in them? Most university articles are non-tolerant of any damage and indicate that some portion of the damaged fruit will drop.


This is what the marks look like http://www.nysipm.cornell.edu/factsheets/treefruit/pests/pc/pc_fig6.asp. If you pick up fruit drops they are not a problem in this area for apples https://entomology.ca.uky.edu/ef202 provided you don’t mind the occasional marks.


Why “later on” bag the apples? I’ve not tried bagging but I was planning to bag my peaches this year. Aren’t you supposed to bag pretty much right off the bat?


Hi MisterGuy! I have bagged my apples for the past five years. I wait until they are almost the size of a nickel, maybe a little larger. I thin at the same time so it becomes a two for one job! Bagging is tedious, but I do get beautiful looking apples. Only ‘earwigs’ get into the bags sometime and those are easily squished!


I have bagged my pears immediately after petal fall for the last three years and I have also got mostly unblemished fruit. My plans this season is to start bagging/thinning apples and pears at about dime size. I think that I can still get a pretty good quality crop and avoid the stress on the stem by waiting a little longer. Bill


My reason for waiting is because some of the stems just need a few more days to gain the strength needed to take the stress of wind blowing the bags. Another big reason is that it is an awful feeling to carefully bag 200 pears and then you get a cold snap that causes the pears to abort (this happened to me last spring on my earliest blooming pear). Bill


Do you spray for PC or are you lucky enough to not be impacted by it up there?


I have never sprayed for curculio or any other fruit eating pest.


I have recently added stone fruit so I will see how that goes.


I just realized that I didn’t answer part of you question. In my area plum curculio is a huge problem on stone fruit but on pears most of the damage I see is comedic or at least they don’t bother a lot of the fruit.


As I understand pears are too hard and crush the grub before it can do anything.


Hi! I only have one tree that has curcs and very few at that (so far) that is my Italian plum, so I spray that tree and the bases of other trees.


I have curculio bad here. Wild plums near here are probably the source. They hit the hybrid plums/pluots/nectarines the hardest. All of those need heavy spray covering well into early summer. They can live and develop if the pear drops for some reason …other then that they are pretty much PC proof (I have never sprayed my pears). Apples will also develop with pc eggs…but…the ones that drops can be full of PC larvae. SO pick up your apple drops or run a pig through to eat them. Sometimes even apples that hang will get PC larvae if the apple stops growing/but doesn’t drop (i’ve seen this often). ///


I agree. Around here many apples will also grow fast enough to crush PC, while some are lost. Here, the bigger issue, in terms of harvest for apples, is codling moth.


Codling moth are very difficult at my location in KS as well Olpea. @39thparallel mentioned a connection with wild trees in this area.



I don’t spray my apple tree after petals fall. I waited for the apple fruits to reach a peanut in size then I bagged the largest apple in each cluster aka King apple. It worked well the last 6 years.



Peanut size seems like a better option than what I have been doing with bagging as the petals drop. Do you see any insect damage while you bagging?


Kelby, my experience here right around the corner from you is that the PC can strike very small fruit, like pea size or slightly bigger if the timing of the weather is right. So I am not sure bagging is possible soon enough. If PC is not deterred by spray apples and pears will be marked and deformed, making them more vulnerable to disease. But I experience very little immediate fruit loss or larva surviving (on pome). Spraying then becomes more critical. If bagging takes place after the damage I don’t know if it will be as effective against disease. I am going to try some bagging this year for the first time. I intend to spray once then bag on a sample quantity.


Like Andy said, those buggers can attack fruitlets very early esp. if the temp is right for them to emerge from the ground. they had wiped out all my peaches in 1-2 days.

For apply, it’s better if apples can size up a bit a bit before you can bag. For me, a dime size. Before they are that size, you can either spray Triazicide at petal fall and 7 days later if pressure is high. If not, 10-14 days is suggested.

For me, I spray Surround at petal fall and a time or two more if needed. Then, I bag. Time consuming but I learn to enjoy bagging. It’s me in the middle of my orchard, a Zen moment :slightly_smiling: I bagged a few hundred apples last year.

I love having perfect, pesticide free apples at the end of the season.

I don’t bag pears. Most of PC scars on my pears are superficial. Pears grow fast and have dense flesh I guess.

My #1 enemy this past year is stinkbugs. With stinkbugs, even my pears sustained some damage. I’ll spray Surround on pears this year a few times…



No insect bite yet at peanut in size.