Help with identifying bug and disease pressure on plum and apple trees


My wife and I bought a house a year ago that came with 10 apple and 3 plum trees. The apples are about 20 years old, and the plums are about 5 years old. Varieties are unknown for sure, but I suspect the apples are Northern Spy and Red Duchess.

We live on the top of a cold hill in central vermont. RIght on the edge of 4a and 3b.

Last year we got no plums and about 150lbs of apples, mostly from one tree. Our neighbors told us it was a bad apple year due to a big year in 2015 and the very dry conditions last year. While I wasn’t watching super closely, I didn’t notice any major disease or bug presence.

This year, wow, tons of apples set everywhere (and one solitary plum) but also way more bugs and (apparent?) disease. Any help identifying and advice on fighting them, either this year or planning for future years, would be much appreciated!

These bugs (photo 1) are on both the plum and apple trees:

While they seem to be eating the leaves on all the apple trees, on one tree in particular (photo 2) they are really going after the fruit:

This rusty disease (photo 3) is mostly on one apple tree, affecting maybe 5% of the leaves:

This is a similar, but seemingly different type of leaf discoloring (photo 4) on a neighboring tree to the one above:

This yellow splotchyness (photo 5) is on a single tree, and maybe just 1% of the leaves:

This tree’s leaves (photo 6) are all curling and a much lighter green than all the other trees. The leaves all curl inward. Last year I assumed it was due to the drought, but we’ve had tons of rain this year.

So, my question is what are the bugs? And should I worry / do anything about the other disease-ish things in the rest of the photos?

These trees haven’t seen active care in about 10 years. I’ve done 2 rounds of heavy pruning over the last 2 winters, but otherwise haven’t done anything else.

Thanks in advance for any advice!

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Looks like Rose Chafer Beetles or something similar, seems to be a fairly wide spread problem with them this year. You will have to check and see what the best insecticide is for your needs. Looks like apple Scab on the leaves with the dark brown spots. Unless it seems to be getting worse I wouldnt probably worry about treating it this year. The yellow leaves could be a few different things but at 1% they arent worth worrying about. The cupping leaves could be a variety of things so hard to say. Water stress, light herbicide drift damage, natural appearance of the leaves. Other than the bugs I wouldnt be overly concerned.


AH, thank you! Definitely Rose Chafer beetles. Looks like their lifecycle is short, and probably near the end for this year. The damage is done, I guess.

The MSU extension says this about control:

As mentioned above, rose chafer beetles are attracted to sandy and grassy areas during their egglaying period. It may not be feasible, but if areas that are obvious sources of the beetle can be changed into a non-grass cover crop or can be fallow for the period of late May until early June, this might force the beetles to seek egglaying sites elsewhere.

My trees all have grass underneath, all the way to the trunk. I’m thinking I should lay down some cardboard and wood chips to out beyond the drip line. Does anyone have experience with countering these beetles like that? Would the rest of the lawn beyond the tree area still harbor the beetle larva enough to be problematic?

I also saw in a couple of places people talking about “Nematodes” to disrupt the beetles in their larval stage. Maybe I mulch under the trees and add some nematodes to do a 1-2 punch for next year? Are there any brand or supplier of nematodes that are recommended for this application?

I did keep track of when I first saw the beetles this year, so next year I will have a timeline to interdict earlier in the process. Most sites recommend carbaryl for direct application. My apples are about 15 feet tall and pretty wide. Is there any economical way to spray something like carbaryl on a tree that size? It seems like a backpack sprayer would take forever (and involve a ladder).

Thanks again for the ID help. I spent quite a while looking at google image results for “apple beetle” on google without success! :slight_smile:

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If you get an extension wand on a backpack sprayer it should not be too much work to spray. I would also look into Surround instead of carbaryl, it provides continuous protection instead of a knock-down of whats on them at the time, and is non-toxic.

Scab seems to be really common in Vermont, its not so bad here. It is not hard to control with sprays in the spring.


Identification needed.

This is on the lower leaves of one Golden Delicious Apple. Quite distinctive.

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CAR, cedar apple rust

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Thank you. There are cedar trees everywhere around here, so no getting away from them.

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Spray with myclobutanil a-couple of times should work. The common brand at Lowe’s and Home Depot is Immunox by Spectracide.