Pear blister mites

Look what I just found on my multi-budded Harrow Delight/ Harvest Queen pear tree.

I will try dillute neam spray. If that doesn’t work, then I might invest in some wettable sulfur per @scottfsmith’s old recommendations on GardenWeb. Unless someone has a better idea…

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I am skeptical of neem for such things, it seems too weak. If you give it a go let us know how it works.

Would you still recommend the wettable sulfur this late in the game?

I have had good luck with it. I would prefer lime-sulphur this late though - read the label and apply the growing season dose. I think our spray amounts guide also gives the growing season rate on L/S. All that pink will turn black (dead) after the spray,


You think this stuff will work?

If thats enough to cover it. It looks like a ready to use hand spray bottle. Me, I have a 20lb bag of 100% wettable sulphur powder, about 10,000 times that quantity :grinning:

Yeah. I only have one semi-dwarf pear tree exhibiting symptoms. Thanks.

I hope sulfur alone will work for you. It did not work for me. I had PBM atfer the tree were fully leafed out . I sprayed it with wettable sulfur spray a few times. It did not work so I gave up. The tree ( Blake Pride) looked aweful for the rest of the year. The following spring I sprayed with lime- sulfur at a late stage of bud swell, it worked . I have used one spray of L- S since.

I wish you good luck.

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I’ll do lime-sulfur at budswell 2018 if things don’t improve this year. Thanks for the “tip.”

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You are one witty guy :smile:

In looking at my logs I only used sulphur one year but it killed it (or it just happened to all die then). Usually I use lime-sulphur which is more potent against things inside leaves as it enters the tissue. Lime-sulphur works very well in the growing season, it should be used more often then but it has this reputation as a dormant spray that it can’t shake.


I have only one bottle so I use it for this PBM. The label does say it is useful for several other things.

Is it possible for peach trees to get pear blister mite? I suspect I have those on mypeach trees.


I’m not aware peach trees are susceptible to pear blister mite. However, peaches are susceptible to other mites. If you can obtain a hand lens, you might try checking the foliage to see if you can see any mites.

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Thank you. What I thought was pear blister mite damage, could be bacterial spot. (Sorry, I know I’m all over the place :slightly_smiling_face:). I posted a picture in disease ID thread. Do you mind taking a look? Thanks.


I looked at the photo, and while it could be bac. spot, it looks perhaps a little more like coryneum blight, or possibly even peach rust. I wouldn’t rule out bac. spot, which looks really close. The bottom photo almost looks like there could be a cambium/root issue.

I know that still leaves a lot of options, so may not be the help you are looking for.

Look at the base of the trunk of the bottom pic and make sure the trunk is undamaged. Do you know what cultivar this is? Certain peach cultivars are very resistant to bac. spot, so we may be able to rule that out. Personally I don’t think it’s bac. spot because it’s never affected trees this late in my locale.

Corneum blight is the closest fit by the photos, but it mainly occurs out west. However, it can occur anywhere in the U.S.

One thing I would rule out is mites. It doesn’t look at all like mites to me.

I would say it’s probably Corneum blight or some cambium issue.

Here’s a pic of a bad case of Corneum blight.

Corneum blight is a fungus. Have you sprayed many fungicides this summer?

Yes I sprayed copper twice while tree was dormant. Also did one spray of copper couple of days ago after I noticed these spots. (Bottle says ok to spray during growing season) But it got much worse over the last few days. Your comment about trunk damage makes sense to me because this is the only tree showing this (I have 2 more somewhat clean trees) and trunk on this tree was damaged but healed now. I’ll take a picture tomorrow and pm you since this is no longer related to pear blister mites I probably shouldn’t post it here.

I’ve never used wettable sulfur at any point- always read it was pretty nasty stuff. Hort-oil has worked without failure on PFM in my experience and I fail to see how sulfur could treat them after they are in the interior of the leaf, although Scott’s anecdotal observations are very carefully construed.

Cornell recommends oil, but once leaf growth starts it’s just too late for it to work so it should be timed about the same time you spray for peach leaf curl.

Here the damage from PBM is usually pretty much cosmetic, the killer is pear psyla which doesn’t come with an easy cure. The best thing is to start with resistant varieties. I have 3 separate insecticides, two specifically for the purpose to keep psyla under control at sites where it has shown up.

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@Matt_in_Maryland has not posted here for almost three months. Hope all is fine with Matt.

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I didn’t notice how long ago this topic occurred. I did not search it up so I wonder why it surfaced.