Explain it to me...plum curculio in apples


Apple maggot hits later. First generation of codling moth tends to lay eggs about the time of the PC, but there are more than one generation of each, where you live.

Staving off the later generations is the real reason for bagging.


It’s in the other thread but I’ll add here. I picked a PC off of an apple tree today and my apples have not dropped all blooms yet. The apples are much smaller than a pea. Granted I only saw one but I know what a PC looks like and I let him walk in my hand for a moment to get a good look. Oh well, it’s always something.


Did you see any egg-laying scars?

Could be they’re not laying yet, so you’d have a couple of days to let the last blossoms fall


No I do not see scars and I was hoping that will be the case. I actually only saw ONE PC. And I looked very closely and saw no scars. I was guessing that I could wait until the petals fall completely with little trouble. That’s what I decided to do anyway, even if I take a little hit with bites ( I don’t seem to have any other choice).

I was mostly just making conversation about how early those little !@#$ invade your orchard.
Folks should consider the first spray as early as possible.

I smashed him anyway.


But of course!


I wouldn’t worry about them walking around, they may take a few bites but they can’t do much damage before the petals are down. BUT, the minute the petals fall you need to get on it! I often am a day or two late and the damage can really rack up. Now I am stuck in a one-week 3-inch rain period so my Surround is not going to work well. Thats one downside of Surround.

I can tell my population is down a bit this year, usually I find about a dozen in the trees to. So far this year I have only found one live bug. I love it when they go crunch :grin:


I’d recommend trapping codling moths and follow a post biofix degree day model to spray. It works really well here in Iowa, even though most of the degree day models were developed elsewhere.

Here are the traps I started out with: https://www.groworganic.com/pvfs-codling-moth-trap-kit-pack-of-2.html

Traps only trap male CM, and should really only be used as surveillance. I think you only need one for a small orchard to get an idea of when CM start showing up.


Do pc typically walk to trees or fly? I was thinking about spraying the trunk of my trees with an encapsulated insecticide as a preventative measure… what’s the best spray for them?


My impression is they mainly walk from one spot to another on a single tree and mainly fly from tree to tree (or to a distant spot on same tree). If they get scared they drop to the ground and they may then walk back up. I’m not sure if they walk up the trunks other times, maybe they do.

Overall I would say spraying the trunks could help… I am now spraying my trunks with Surround to slow him down.


Do PC bites cause some apples to drop off the tree?


Apples stay on, usually the PC worm is crushed by the growing apple and you get those gnarly-shaped fruits at harvest. Crabs are more likely to have a PC make it to maturity, even those don’t drop though.


It’s the downside of any spray - downpour washes it off, even with sticker


Should I bag apples that were “bit” by PC? I mean, I don’t see a crescent scar, but a little hole, like they drank some apple juice and changed their mind…


Could be codling moth. They hit apples right after petal fall here, and they are bad this year. You can look for frass, or staining from frass, on the outside of the apple. You can also cut one open to see if it is a caterpillar (has legs) located at the center of the fruit. If it is a caterpillar not at the center, it is probably something else, like oriental fruit moth.


Might be, but I caught one PC getting drunk on another apple leaving a little circular hole in the fruit. I’ll cut one open.


A few pest can feed on the same fruit. When I thinned apple last week, I saw pin holes and crescent marks on several of my fruit. It is not uncommon to see two different worms in one apple, peach, plum.

I took this pic to show multiple scars from PC. What I did not show was other pin holes spots near calyx. I could be OFM or coddling moth as @AJfromElmiraNY mentioned.


Thanks to both of you, Mamuang and AJfromElminaNY. I did open the fruitlets and in some, found a hole with an egg, a worm or nothing at all. I ended up cuting the pieces where the “sting” was out of the remaining apples and I am now hoping the fruits will heal! I had already bagged a lot of spotless apples so I won’t be too sad if I lose some.


Several people here have reported success in doing this